11-18
ensure that the nose does not continue yawing to the right. If
a go-around is required, increasing the collective too much or
too rapidly with airspeeds below translational lift may cause
a rapid spinning to the right.
Once the helicopter has landed and is sliding/rolling to a
stop, the heading can be controlled with a combination of
collective, cyclic and throttle. To turn the nose to the right,
raise the collective or apply aft cyclic. The throttle may be
increased as well if it is not in the full open position. To turn
the nose to the left, lower the collective or apply forward
cyclic. The throttle may be decreased as well if it is not
already at flight idle.
Loss of Tail Rotor Effectiveness (LTE)
Loss of tail rotor effectiveness (LTE) or an unanticipated
yaw is defined as an uncommanded, rapid yaw towards the
advancing blade which does not subside of its own accord.
It can result in the loss of the aircraft if left unchecked. It is
very important for pilots to understand that LTE is caused
by an aerodynamic interaction between the main rotor and
tail rotor and not caused from a mechanical failure. Some
helicopter types are more likely to encounter LTE due to the
normal certification thrust produced by having a tail rotor
that, although meeting certification standards, is not always
able to produce the additional thrust demanded by the pilot.
A helicopter is a collection of compromises. Compare the
size of an airplane propeller to that of a tail rotor. Then,
consider the horsepower required to run the propeller. For
example, a Cessna 172P is equipped with a 160-horsepower
(HP) engine. A Robinson R-44 with a comparably sized tail
rotor is rated for a maximum of 245 HP. If you assume the
tail rotor consumes 50 HP, only 195 HP remains to drive
the main rotor. If the pilot were to apply enough collective
to require 215 HP from the engine, and enough left pedal to
require 50 HP for the tail rotor, the resulting engine overload
would lead to one of two outcomes: slow down (reduction
in rpm) or premature failure. In either outcome, antitorque
would be insufficient and total lift might be less than needed
to remain airborne.
Every helicopter design requires some type of antitorque
system to counteract main rotor torque and prevent spinning
once the helicopter lifts off the ground. A helicopter is heavy,
and the powerplant places a high demand on fuel. Weight
penalizes performance, but all helicopters must have an
antitorque system, which adds weight. Therefore, the tail
rotor is certified for normal flight conditions. Environmental
forces can overwhelm any aircraft, rendering the inherently
unstable helicopter especially vulnerable.
As with any aerodynamic condition, it is very important for
pilots to not only to understand the definition of LTE, but
more importantly, how and why it happens, how to avoid
it, and lastly, how to correct it once it is encountered. We
must first understand the capabilities of the aircraft or even
better what it is not capable of doing. For example, if you
were flying a helicopter with a maximum gross weight of
5,200 lb, would you knowingly try to take on fuel, baggage
and passengers causing the weight to be 5,500 lb? A wise
professional pilot should not ever exceed the certificated
maximum gross weight or performance flight weight for any
aircraft. The manuals are written for safety and reliability.
The limitations and emergency procedures are stressed
because lapses in procedures or exceeding limitations can
result in aircraft damage or human fatalities. At the very least,
exceeding limitations will increase the costs of maintenance
and ownership of any aircraft and especially helicopters.
Overloaded parts may fail before their designed lifetime. There
are no extra parts in helicopters. The respect and discipline
pilots exercise in following flight manuals should also be
applied to understanding aerodynamic conditions. If flight
envelopes are exceeded, the end results can be catastrophic.
LTE is an aerodynamic condition and is the result of a control
margin deficiency in the tail rotor. It can affect all single-rotor
helicopters that utilize a tail rotor. The design of main and
tail rotor blades and the tail boom assembly can affect the
characteristics and susceptibility of LTE but will not nullify
the phenomenon entirely. Translational lift is obtained by
any amount of clean air through the main rotor disk. Chapter
2, Aerodynamics of Flight, discusses translational lift with
respect to the main rotor blade, explaining that the more
clean air there is going through the rotor disk, the more
efficient it becomes. The same holds true for the tail rotor.
As the tail rotor works in less turbulent air, it reaches a point
of translational thrust. At this point, the tail rotor becomes
aerodynamically efficient and the improved efficiency
produces more antitorque thrust. The pilot can determine
when the tail rotor has reached translational thrust. As more
antitorque thrust is produced, the nose of the helicopter
yaws to the left (opposite direction of the tail rotor thrust),
forcing the pilot to correct with right pedal application
(actually decreasing the left pedal). This, in turn, decreases
the AOA in the tail rotor blades. Pilots should be aware of the
characteristics of the helicopter they fly and be particularly
aware of the amount of tail rotor pedal typically required for
different flight conditions.
LTE is a condition that occurs when the flow of air through
a tail rotor is altered in some way, by altering the angle or
speed at which the air passes through the rotating blades of
the tail rotor disk. As discussed in the previous paragraph, an
effective tail rotor relies on a stable and relatively undisturbed
11-19
0°
30°
60°
90°
120°
150°
180°
210°
240°
270°
300°
330°
Region of disk
vortex interference
10 knots
360°
15 knots 20 knots
315°
285°
Wind
Figure 11-9. Main rotor disk vortex interference.
Region of possible yaw introduction by weathercock stability
0°
30°
60°
90°
120°
150°
180°
210°
240°
270°
300°
330°
10 knots
360°
5 knots
15 knots
17 knots
Wind
Figure 11-10. Weathercock stability.
airflow in order to provide a steady and constant antitorque
reaction. The pitch and AOA of the individual blades will
determine the thrust. A change to either of these alters the
amount of thrust generated. A pilot’s yaw pedal input causes
a thrust reaction from the tail rotor. Altering the amount of
thrust delivered for the same yaw input creates an imbalance.
Taking this imbalance to the extreme will result in the loss
of effective control in the yawing plane, and LTE will occur.
This alteration of tail rotor thrust can be affected by numerous
external factors. The main factors contributing to LTE are:
1. Airflow and downdraft generated by the main rotor
blades interfering with the airflow entering the tail
rotor assembly.
2. Main blade vortices developed at the main blade tips
entering the tail rotor disk.
3. Turbulence and other natural phenomena affecting the
airflow surrounding the tail rotor.
4. A high-power setting, hence large main rotor
pitch angle, induces considerable main rotor blade
downwash and hence more turbulence than when the
helicopter is in a low power condition.
5. A slow forward airspeed, typically at speeds where
translational lift and translational thrust are in the
process of change and airflow around the tail rotor
will vary in direction and speed.
6. The airflow relative to the helicopter;
a. Worst case—relative wind within ±15° of the
10 o’clock position, generating vortices that
can blow directly into the tail rotor. This is
dictated by the characteristics of the helicopters
aerodynamics of tailboom position, tail rotor size
and position relative to the main rotor and vertical
stabilizer, size and shape. [Figure 11-9]
b. Weathercock stability—tailwinds from 120° to
240° [Figure 11-10] , such as left crosswinds,
causing high pilot workload.
c. Tail rotor vortex ring state (210° to
330°). [Figure 11-11] Winds within this region
will result in the development of the vortex ring
state of the tail rotor.
7. Combinations (a, b, c) of these factors in a particular
situation can easily require more antitorque than the
helicopter can generate and in a particular environment
LTE can be the result.
Certain flight activities lend themselves to being at higher
risk of LTE than others. For example, power line and pipeline
patrol sectors, low speed aerial filming/photography as well
as in the Police and Helicopter Emergency Medical Services
(EMS) environments can find themselves in low-and-slow
situations over geographical areas where the exact wind speed
and direction are hard to determine.
11-20
0°
30°
60°
90°
120°
150°
180°
210°
240°
270°
300°
330°
Region of roughness due to tail rotor vortex ring state
10 knots
360°
5 knots
15 knots
17 knots
Wind
Figure 11-11. Tail rotor vortex ring state.
Unfortunately, the aerodynamic conditions that a helicopter
is susceptible to are not explainable in black and white terms.
LTE is no exception. There are a number of contributing
factors, but what is more important in preventing LTE is to
note them, and then to associate them with situations that
should be avoided. Whenever possible, pilots should learn
to avoid the following combinations:
1. Low and slow flight outside of ground effect.
2. Winds from ±15º of the 10 o’clock position and
probably on around to 5 o’clock position [Figure 11-9]
3. Tailwinds that may alter the onset of translational lift
and translational thrust, and hence induce high power
demands and demand more anti-torque (left pedal)
than the tail rotor can produce.
4. Low speed downwind turns.
5. Large changes of power at low airspeeds.
6. Low speed flight in the proximity of physical
obstructions that may alter a smooth airflow to both
the main rotor and tail rotor.
Pilots who put themselves in situations where the combinations
above occur should know that they are likely to encounter
LTE. The key is not to put the helicopter in a compromising
condition, while at the same time being educated enough
to recognize the onset of LTE and being prepared to react
quickly to it before the helicopter cannot be controlled.
Early detection of LTE, followed by the immediate flight
control application of corrective action, applying forward
cyclic to regain airspeed, applying right pedal not left as
necessary to maintain rotor rpm, and reducing the collective
(thus reducing the high-power demand on the tail rotor), is the
key to a safe recovery. Pilots should always set themselves
up when conducting any maneuver to have enough height
and space available to recover in the event they encounter
an aerodynamic situation such as LTE.
Understanding the aerodynamic phenomenon of LTE is by
far the most important factor in preventing an LTE-related
accident, and maintaining the ability and option either to go
around if making an approach or pull out of a maneuver safely
and re-plan, is always the safest option. Having the ability to
fly away from a situation and re-think the possible options
should always be part of a pilot's planning process in all phases
of flight. Unfortunately, there have been many pilots who
have idled a good engine and fully functioning tail rotor disk
and autorotated a perfectly airworthy helicopter to the crash
site because they misunderstood or misperceived both the
limitations of the helicopter and the aerodynamic situation.
Main Rotor Disk Interference (285–315°)
Refer to Figure 11-9. Winds at velocities of 10–30 knots from
the left front cause the main rotor vortex to be blown into the
tail rotor by the relative wind. This main rotor disk vortex
causes the tail rotor to operate in an extremely turbulent
environment. During a right turn, the tail rotor experiences a
reduction of thrust as it comes into the area of the main rotor
disk vortex. The reduction in tail rotor thrust comes from the
airflow changes experienced at the tail rotor as the main rotor
disk vortex moves across the tail rotor disk.
The effect of the main rotor disk vortex initially increases the
AOA of the tail rotor blades, thus increasing tail rotor thrust.
The increase in the AOA requires that right pedal pressure
be added to reduce tail rotor thrust in order to maintain the
same rate of turn. As the main rotor vortex passes the tail
rotor, the tail rotor AOA is reduced. The reduction in the
AOA causes a reduction in thrust and right yaw acceleration
begins. This acceleration can be surprising, since previously
adding right pedal to maintain the right turn rate. This thrust
reduction occurs suddenly, and if uncorrected, develops
into an uncontrollable rapid rotation about the mast. When
operating within this region, be aware that the reduction in
tail rotor thrust can happen quite suddenly, and be prepared
to react quickly to counter this reduction with additional left
pedal input.
Weathercock Stability (120–240°)
In this region, the helicopter attempts to weathervane,
or weathercock, its nose into the relative wind.
[Figure 11-10] Unless a resisting pedal input is made, the
helicopter starts a slow, uncommanded turn either to the right
11-21
or left, depending upon the wind direction. If the pilot allows
a right yaw rate to develop and the tail of the helicopter moves
into this region, the yaw rate can accelerate rapidly. In order
to avoid the onset of LTE in this downwind condition, it is
imperative to maintain positive control of the yaw rate and
devote full attention to flying the helicopter.
Tail Rotor Vortex Ring State (210–330°)
Winds within this region cause a tail rotor vortex ring state to
develop. [Figure 11-11] The result is a nonuniform, unsteady
flow into the tail rotor. The vortex ring state causes tail
rotor thrust variations, which result in yaw deviations. The
net effect of the unsteady flow is an oscillation of tail rotor
thrust. Rapid and continuous pedal movements are necessary
to compensate for the rapid changes in tail rotor thrust when
hovering in a left crosswind. Maintaining a precise heading
in this region is difficult, but this characteristic presents
no significant problem unless corrective action is delayed.
However, high pedal workload, lack of concentration, and
overcontrolling can lead to LTE.
When the tail rotor thrust being generated is less than the
thrust required, the helicopter yaws to the right. When
hovering in left crosswinds, concentrate on smooth pedal
coordination and do not allow an uncommanded right yaw to
develop. If a right yaw rate is allowed to build, the helicopter
can rotate into the wind azimuth region where weathercock
stability then accelerates the right turn rate. Pilot workload
during a tail rotor vortex ring state is high. Do not allow a
right yaw rate to increase.
LTE at Altitude
At higher altitudes where the air is thinner, tail rotor thrust
and efficiency are reduced. Because of the high-density
altitude, powerplants may be much slower to respond to
power changes. When operating at high altitudes and high
gross weights, especially while hovering, the tail rotor thrust
may not be sufficient to maintain directional control, and
LTE can occur. In this case, the hovering ceiling is limited
by tail rotor thrust and not necessarily power available. In
these conditions, gross weights need to be reduced and/
or operations need to be limited to lower density altitudes.
This may not be noted as criteria on the performance charts.
Reducing the Onset of LTE
To help reduce the onset of LTE, follow these steps:
1. Maintain maximum power-on rotor rpm. If the main
rotor rpm is allowed to decrease, the antitorque thrust
available is decreased proportionally.
2. Avoid tailwinds below airspeeds of 30 knots. If loss
of translational lift occurs, it results in an increased
power demand and additional antitorque pressures.
3. Avoid OGE operations and high-power demand
situations below airspeeds of 30 knots at low altitudes.
4. Be especially aware of wind direction and velocity
when hovering in winds of about 8–12 knots. A loss
of translational lift results in an unexpected high power
demand and an increased antitorque requirement.
5. Be aware that if a considerable amount of left pedal
is being maintained, a sufficient amount of left pedal
may not be available to counteract an unanticipated
right yaw.
6. Be alert to changing wind conditions, which may be
experienced when flying along ridge lines and around
buildings.
7. Execute right turns slowly. This limits the effects of
rotating inertia, and decreases loading on the tailrotor
to control yawing.
Recovery Technique (Uncontrolled Right Yaw)
If a sudden unanticipated right yaw occurs, the following
recovery technique should be performed. Apply full left
pedal. Simultaneously, apply forward cyclic control to
increase speed. If altitude permits, reduce power. As recovery
is affected, adjust controls for normal forward flight. A
recovery path must always be planned, especially when
terminating to an OGE hover and executed immediately if
an uncommanded yaw is evident.
Collective pitch reduction aids in arresting the yaw rate but
may cause an excessive rate of descent. Any large, rapid
increase in collective to prevent ground or obstacle contact
may further increase the yaw rate and decrease rotor rpm.
The decision to reduce collective must be based on the pilot’s
assessment of the altitude available for recovery.
If the rotation cannot be stopped and ground contact is
imminent, an autorotation may be the best course of action.
Maintain full left pedal until the rotation stops, then adjust to
maintain heading. For more information on LTE, see Advisory
Circular (AC) 90-95, Unanticipated Right Yaw in Helicopters.
Main Drive Shaft or Clutch Failure
The main drive shaft, located between the engine and the main
rotor transmission, provides engine power to the main rotor
transmission. In some helicopters, particularly those with
piston engines, a drive belt is used instead of a drive shaft.
A failure of the drive shaft clutch or belt has the same effect
as an engine failure because power is no longer provided to
the main rotor and an autorotation must be initiated. There
are a few differences, however, that need to be taken into
11-22
consideration. If the drive shaft or belt breaks, the lack of any
load on the engine results in an overspeed. In this case, the
throttle must be closed in order to prevent any further damage.
In some helicopters, the tail rotor drive system continues to
be powered by the engine even if the main drive shaft breaks.
In this case, when the engine unloads, a tail rotor overspeed
can result. If this happens, close the throttle immediately and
enter an autorotation. The pilot must be knowledgeable of the
specific helicopter’s system and failure modes.
Pilots should keep in mind that when there is any suspected
mechanical malfunction, first and foremost they should
always attempt to maintain rotor rpm. If the rotor rpm is at the
normal indication with normal power settings, an instrument
failure might be occurring, and it would be best to fly the
helicopter to a safe landing area. If the rotor rpm is in fact
decreasing or low, then there is a drive line failure.
Hydraulic Failure
Many helicopters incorporate the use of hydraulic actuators to
overcome high control forces. A hydraulic system consists of
actuators, also called servos, on each flight control; a pump,
which is usually driven by the main rotor transmission;
and a reservoir to store the hydraulic fluid. A switch in the
cockpit can turn the system off, although it is left on during
normal conditions. A pressure indicator in the cockpit may
be installed to monitor the system.
An impending hydraulic failure can be recognized by a
grinding or howling noise from the pump or actuators,
increased control forces and feedback, and limited control
movement. The required corrective action is stated in detail
in the RFM. In most cases, airspeed needs to be reduced in
order to reduce control forces. The hydraulic switch and
circuit breaker should be checked and recycled. If hydraulic
power is not restored, make a shallow approach to a running
or roll-on landing. This technique is used because it requires
less control force and pilot workload. Additionally, the
hydraulic system should be disabled by placing the switch
in the off position. The reason for this is to prevent an
inadvertent restoration of hydraulic power, which may lead
to overcontrolling near the ground.
In those helicopters in which the control forces are so high
that they cannot be moved without hydraulic assistance, two
or more independent hydraulic systems are installed. Some
helicopters use hydraulic accumulators to store pressure that
can be used for a short time while in an emergency if the
hydraulic pump fails. This gives enough time to land the
helicopter with normal control.
Governor or Fuel Control Failure
Governors and fuel control units automatically adjust engine
power to maintain rotor rpm when the collective pitch
is changed. If the governor or fuel control unit fails, any
change in collective pitch requires manual adjustment of
the throttle to maintain correct rpm. In the event of a high
side failure, the engine and rotor rpm tend to increase above
the normal range due to the engine being commanded to
put out too much power. If the rpm cannot be reduced and
controlled with the throttle, close the throttle and enter an
autorotation. If the failure is on the low side, the engine
output is allowed to go below the collective and normal
rpm may not be attainable, even if the throttle is manually
controlled. In this case, the collective has to be lowered to
maintain rotor rpm. A running or roll-on landing may be
performed if the engine can maintain sufficient rotor rpm. If
there is insufficient power, enter an autorotation. As stated
previously in this chapter, before responding to any type of
mechanical failure, pilots should confirm that rotor rpm is
not responding to flight control inputs. If the rotor rpm can
be maintained in the green operating range, the failure is in
the instrument, and not mechanical.
Abnormal Vibration
With the many rotating parts found in helicopters, some
vibration is inherent. A pilot needs to understand the
cause and effect of helicopter vibrations because abnormal
vibrations cause premature component wear and may even
result in structural failure. With experience, a pilot learns
what vibrations are normal and those that are abnormal
and can then decide whether continued flight is safe or not.
Helicopter vibrations are categorized into low, medium, or
high frequency.
Low-Frequency Vibrations
Low-frequency vibrations (100–500 cycles per minute) usually
originate from the main rotor disk. The main rotor operational
range, depending on the helicopter, is usually between 320
and 500 rpm. A rotor blade that is out of track or balance will
cause a cycle to occur with every rotation. The vibration may
be felt through the controls, the airframe, or a combination
of both. The vibration may also have a definite direction
of push or thrust. It may be vertical, lateral, horizontal, or
even a combination of these. Normally, the direction of the
vibration can be determined by concentrating on the feel of
the vibration, which may push a pilot up and down, backwards
and forwards, or in the case of a blade being out of phase, from
side to side. The direction of the vibration and whether it is
felt in the controls or the airframe is important information for
the mechanic when he or she troubleshoots the source. Out-
of-track or out-of-balance main rotor blades, damaged blades,
11-23
worn bearings, dampers out of adjustment, or worn parts are
possible causes of low frequency vibrations.
Medium- and High-Frequency Vibrations
Medium-frequency vibrations (1,000–2,000 cycles per
minute) range between the low frequencies of the main rotor
(100–500 cycles per minute) and the high frequencies (2,100
cycles per minute or higher) of the engine and tail rotor.
Depending on the helicopter, medium-frequency vibration
sources may be engine and transmission cooling fans, and
accessories such as air conditioner compressors, or driveline
components. Medium-frequency vibrations are felt through
the entire airframe, and prolonged exposure to the vibrations
will result in greater pilot fatigue.
Most tail rotor vibrations fall into the high-frequency range
(2,100 cycles per minute or higher) and can be felt through
the tail rotor pedals as long as there are no hydraulic actuators
to dampen out the vibration. This vibration is felt by the pilot
through his or her feet, which are usually “put to sleep” by
the vibration. The tail rotor operates at approximately a 6:1
ratio with the main rotor, meaning for every one rotation
of the main rotor the tail rotor rotates 6 times. A main
rotor operating rpm of 350 means the tail rotor rpm would
be 2,100 rpm. Any imbalance in the tail rotor disk is very
harmful as it can cause cracks to develop and rivets to work
loose. Piston engines usually produce a normal amount of
high-frequency vibration, which is aggravated by engine
malfunctions, such as spark plug fouling, incorrect magneto
timing, carburetor icing and/or incorrect fuel/air mixture.
Vibrations in turbine engines are often difficult to detect as
these engines operate at a very high rpm. Turbine engine
vibration can be at 30,000 rpm internally, but common
transmission speeds are in the 1,000 to 3,000 rpm range for
the output shaft. The vibrations in turbine engines may be
short lived as the engine disintegrates rapidly when damaged
due to high rpm and the forces present.
Tracking and Balance
Modern equipment used for tracking and balancing the main
and tail rotor blades can also be used to detect other vibrations
in the helicopter. These systems use accelerometers mounted
around the helicopter to detect the direction, frequency, and
intensity of the vibration. The built-in software can then
analyze the information, pinpoint the origin of the vibration,
and suggest the corrective action.
The use of a system such as a health and usage monitoring
system (HUMS) provides the operator the ability to record
engine and transmission performance and provide rotor track
and balance. This system has been around for over 30 years
and is now becoming more affordable, more capable, and
more commonplace in the rotorcraft industry.
Multiengine Emergency Operations
Single-Engine Failure
When one engine has failed, the helicopter can often maintain
altitude and airspeed until a suitable landing site can be
selected. Whether or not this is possible becomes a function
of such combined variables as aircraft weight, density
altitude, height above ground, airspeed, phase of flight,
and single-engine capability. Environmental response time
and control technique may be additional factors. Caution
must be exercised to correctly identify the malfunctioning
engine since there is no telltale yawing as occurs in most
multiengine airplanes. Shutting down the wrong engine
could be disastrous!
Even when flying multiengine powered helicopters, rotor rpm
must be maintained at all costs, because fuel contamination has
been documented as the cause for both engines failing in flight.
Dual-Engine Failure
The flight characteristics and the required crew member
control responses after a dual-engine failure are similar to
those during a normal power-on descent. Full control of the
helicopter can be maintained during autorotational descent.
In autorotation, as airspeed increases above 70–80 KIAS, the
rate of descent and glide distance increase significantly. As
airspeed decreases below approximately 60 KIAS, the rate
of descent increases and glide distance decreases.
Lost Procedures
Pilots become lost while flying for a variety of reasons, such
as disorientation, flying over unfamiliar territory, or visibility
that is low enough to render familiar terrain unfamiliar. When
a pilot becomes lost, the first order of business is to fly the
aircraft; the second is to implement lost procedures. Keep
in mind that the pilot workload will be high, and increased
concentration will be necessary. If lost, always remember to
look for the practically invisible hazards, such as wires, by
searching for their support structures, such as poles or towers,
which are almost always near roads.
If lost, follow common sense procedures.
• Try to locate any large landmarks, such as lakes, rivers,
towers, railroad tracks, or Interstate highways. If a
landmark is recognized, use it to find the helicopter’s
location on the sectional chart. If flying near a town or
city, a pilot may be able to read the name of the town
on a water tower or even land to ask for directions.
• If no town or city is nearby, the first thing a pilot should
do is climb. An increase in altitude increases radio and
navigation reception range as well as radar coverage.
11-24
risk associated with being lost is waiting too long to land in a
safe area. Helicopter pilots should land before fuel exhaustion
occurs because maneuvering with low fuel levels could cause
the engine to stop due to fuel starvation as fuel sloshes or
flows away from the pickup port in the tank.
If lost and low on fuel, it is advisable to make a precautionary
landing. Preferably, land near a road or in an area that would
allow space for another helicopter to safely land and provide
assistance. Having fuel delivered is a minor inconvenience
when compared to having an accident. Once on the ground,
pilots may seek assistance.
VFR Flight into Instrument Meteorological
Conditions
Helicopters, unlike airplanes, generally operate under Visual
Flight Rules (VFR) and require pilots to maintain aircraft
control by visual cues. However, when unforecast weather
leads to degraded visibility, the pilot may be at increased
risk of Inadvertent flight into Instrument Meteorological
Conditions (IIMC). During an IIMC encounter, the pilot
may be unprepared for the loss of visual reference, resulting
in a reduced ability to continue safe flight. IIMC is a life-
threatening emergency for any pilot. To capture these IIMC
events, the Commercial Aviation Safety Team (CAST) and
International Civil Aviation Organization (ICAO) Common
Taxonomy Team (CICTT) categorizes this occurrence as
Unintended flight in Instrument Meteorological Conditions
(UIMC). This term is also recognized by the National
Transportation Safety Board (NTSB) and Federal Aviation
Administration (FAA). It is used to classify occurrences
(accidents and incidents) at a high level to improve the
capacity to focus on common safety issues and complete
analysis of the data in support of safety initiatives.
The onset of IIMC may occur gradually or suddenly, has
no simple procedural exit, and is unlike flight training by
reference to while in Visual Meteorological Conditions
(VMC). Most training helicopters are not equipped or
certified to fly under Instrument Flight Rules (IFR).
Therefore, General Aviation (GA) helicopter pilots may not
have the benefit of flight in actual Instrument Meteorological
Conditions (IMC) during their flight training. Helicopter
pilots that encounter IIMC may experience physiological
illusions which can lead to spatial disorientation and loss of
aircraft control. Even with some instrument training, many
available and accessible helicopters are not equipped with
the proper augmented safety systems or autopilots, which
would significantly aid in helicopter control during an
IIMC emergency. The need to use outside visual references
is natural for helicopter pilots because much of their flight
training is based upon visual cues, not on flight instruments.
This primacy can only be overcome through significant
instrument training. Additionally, instrument flight may be
• Navigation aids, dead reckoning, and pilotage are
skills that can be used as well.
• Do not forget air traffic control (ATC)—controllers
assist pilots in many ways, including finding a lost
helicopter. Once communication with ATC has been
established, follow their instructions.
These common-sense procedures can be easily remembered by
using the four Cs: Climb, Communicate, Confess, and Comply.
• Climb for a better view, improved communication and
navigation reception, and terrain avoidance.
• Communicate by calling the nearest flight service
station (FSS)/automated flight service station (AFSS)
on 122.2 MHz. If the FSS/AFSS does not respond,
call the nearest control tower, center, or approach
control. For frequencies, check the chart in the vicinity
of the last known position. If that fails, switch to
the emergency radio frequency (121.5 MHz) and
transponder code (7700).
• Report the lost situation to ATC and request help.
• Comply with controller instructions.
Pilots should understand the services provided by ATC and
the resources and options available. These services enable
pilots to focus on aircraft control and help them make better
decisions in a time of stress.
When contacting ATC, pilots should provide as much
information as possible because ATC uses the information
to determine what kind of assistance it can provide with
available assets and capabilities. Information requirements
vary depending on the existing situation, but at a minimum
a pilot should provide the following information:
• Aircraft identification and type
• Nature of the emergency
• Aviator’s desires
To reduce the chances of getting lost in the first place, use
flight following through active contact with an aircraft during
flight either by radio or through automated flight following
systems when it is available, monitor checkpoints no more
than 25 miles apart, keep navigation aids such as Very
High-Frequency Omni-Directional Range (VOR) tuned in,
and maintain good situational awareness. Flight following
provides ongoing surveillance information to assist pilots in
avoiding collisions with other aircraft.
Getting lost is a potentially dangerous situation for any
aircraft, especially when low on fuel. Due to the helicopter’s
unique ability to land almost anywhere, pilots have more
flexibility than other aircraft as to landing site. An inherent
11-25
intimidating to some and too costly for others. As a result,
many helicopter pilots choose not to seek an instrument
rating.
While commercial helicopter operators often prefer their
pilots to be instrument rated, fatal accidents still occur as
a result of IIMC. Many accidents can be traced back to
the pilot’s inability to recover the helicopter after IIMC
is encountered, even with adequate equipment installed.
Therefore, whether instrument rated or not, all pilots should
understand that avoiding IIMC is critical.
A good practice for any flight is to set and use personal
minimums, which should be more conservative than those
required by regulations for VFR flight. In addition, a thorough
preflight and understanding of weather conditions that may
contribute to the risk of IMC developing along a planned
route of flight is essential for safety. Pilots should recognize
deteriorating weather conditions so the route of flight can be
changed or a decision made to terminate the flight and safely
land at a suitable area, well before IIMC occurs. If weather
conditions deteriorate below the pilot’s personal minimums
during flight, a pilot who understands the risks of IIMC
knows that he or she is at an en route decision point, where
it is necessary to either turn back to the departure point or
immediately land somewhere safe to wait until the weather
has cleared. Pilots should recognize that descent below a
predetermined minimum altitude above ground level (AGL)
(for example, 500 feet AGL) to avoid clouds or, slowing
the helicopter to a predetermined minimum airspeed (for
example, slowing to 50 KIAS) to reduce the rate of closure
from the deteriorating weather conditions, indicates the
decision point had been reached. Ceilings that are lower than
reported and/or deteriorating visibility along the route of
flight should trigger the decision to discontinue and amend
the current route to avoid IIMC.
If the helicopter pilot is instrument rated, it is advisable to
maintain instrument currency and proficiency as this may
aid the pilot in a safe recovery from IIMC. A consideration
for instrument rated pilots when planning a VFR flight
should include a review of published instrument charts for
safe operating altitudes, e.g. minimum safe altitude (MSA),
minimum obstruction clearance altitude (MOCA), minimum
in VMC throughout a flight: off-route altitude (MORA),
etc. If IIMC occurs, the pilot may consider a climb to a safe
altitude. Once the helicopter is stabilized, the pilot should
declare an emergency with air traffic control (ATC). It is
imperative that the pilot commit to controlling the helicopter
and remember to aviate, navigate, and finally communicate.
Often communication is attempted first, as it is natural to
look for help in stressful situations. This may distract the
pilot from maintaining control of the helicopter.
If the pilot is not instrument rated, instrument current nor
proficient, or is flying a non-IFR equipped helicopter,
remaining in VMC is paramount. Pilots who are not trained
or proficient in flight solely by reference to instruments have
a tendency to attempt to maintain flight by visual ground
reference, which tends to result in flying at lower altitudes,
just above the trees or by following roads. The thought process
is that, "as long as I can see what is below me, I can continue
to my intended destination." Experience and statistical data
indicate that attempting to continue VFR flight into IMC can
often lead to a fatal outcome as pilots often fixate on what
they see below them and are unable to see the hazards ahead
of them (e.g., power lines, towers, rising terrain, etc.). By
the time the pilot sees the hazard, it is either too late to avoid
a collision, or while successfully maneuvering to avoid an
obstacle, the pilot becomes disoriented.
Flying at night involves even more conservative personal
minimums to ensure safety and avoidance of IIMC than
daytime flying. At night, deteriorating weather conditions
may be difficult to detect. Therefore, pilots should ensure
that they not only receive a thorough weather briefing, but
that they remain vigilant for unforecasted weather during
their flight. The planned route should include preselected
landing sites that will provide options to the pilot in the
event a precautionary landing is required to avoid adverse
weather conditions. As a pilot gains night flight experience
their ability to assess weather during a flight will improve.
Below are some basic guidelines to assist a pilot to remain
in VMC throughout a flight:
1. Slowly turn around if threatened by deteriorating
visual cues and proceed back to VMC or to the first
safe landing area if the weather ahead becomes
questionable. Remember that prevention is paramount.
2. Do not proceed further on a course when the terrain
ahead is not clearly discernible.
3. Delay or consider cancelling the flight if weather
conditions are already questionable, could deteriorate
significantly based on forecasts, or if you are uncertain
whether the flight can be conducted safely. Often, a
gut feeling can provide a warning that unreasonable
risks are present.
4. Always have a safe landing area (such as large open
areas or airports) in mind for every route of flight.
There are five basic steps that every pilot should be familiar
with, and which should be executed immediately at the onset
of IIMC, if applicable. However, remember that if you are
not trained to execute the following maneuvers solely by
reference to instruments, or your aircraft is not equipped
11-26
Food cannot be subject to deterioration due to heat or cold. There
should be at least 10,000 calories for each person on board, and it
should be stored in a sealed waterproof container. It should have
been inspected within the previous 6 months, verifying the amount
and satisfactory condition of the contents.
A supply of water
Cooking utensils
Matches in a waterproof container
A portable compass
An ax weighing at least 2.5 pounds with a handle not less than 28 inches
in length
A flexible saw blade or equivalent cutting tool
30 feet of snare wire and instructions for use
Fishing equipment, including still-fishing bait and gill net with not more
than a two-inch mesh
Mosquito nets or netting and insect repellent sufficient to meet the
needs of all persons aboard, when operating in areas where insects
are likely to be hazardous
A signaling mirror
At least three pyrotechnic distress signals
A sharp, quality jackknife or hunting knife
A suitable survival instruction manual
Flashlight with spare bulbs and batteries
Portable emergency locator transmitter (ELT) with spare batteries
Stove with fuel or a self-contained means of providing heat for cooking
Tent(s) to accommodate everyone on board
Additional items for winter operations:
• Winter sleeping bags for all persons when the
temperature is expected to be below 7 °C
• Two pairs of snow shoes
• Spare ax handle
• Ice chisel
• Snow knife or saw knife
EMERGENCY EQUIPMENT AND SURVIVAL GEAR
Figure 11-12. Emergency equipment and survival gear.
with such instruments, this guidance may be less beneficial
to you and loss of helicopter control may occur:
1. Level the “wings” – level the bank angle using the
attitude indicator.
2. Attitude – set a climb attitude that achieves a safe
climb speed appropriate to your type of helicopter.
This is often no more than 10° of pitch up on the
attitude indicator.
3. Airspeed – verify that the attitude selected has
achieved the desired airspeed. It is critical to
recognize that slower airspeeds, closer to effective
translational lift, may require large control inputs and
will decrease stability, making recover impossible
while in UIMC.
4. Power – adjust to a climb power setting relative to the
desired airspeed. This should be executed concurrent
with steps 2 and 3.
5. Heading and Trim – pick a heading known to be free
of obstacles and maintain it. This will likely be the
heading you were already on, which was planned and
briefed. Set the heading bug, if installed, to avoid over-
controlling your bank. Maintain coordinated flight so
that an unusual attitude will not develop.
Try to avoid immediately turning 180°. Turning around is
not always the safest route and executing a turn immediately
after UIMC may lead to spatial disorientation. If a 180° turn
is the safest option, first note the heading you are on then
begin the turn to the reciprocal heading, but only after stable
flight is achieved (items 1 through 5 above) and maintain
a constant rate of turn appropriate to the selected airspeed.
Each encounter with UIMC is unique, and no single
procedure can ensure a safe outcome. Considerations in
determining the best course of action upon encountering
UIMC should include, at a minimum, terrain, obstructions,
freezing levels, aircraft performance and limitations, and
availability of ATC services.
There are new technologies being developed regarding
aircraft design, enhanced and lower-cost technologies,
and aircraft certification. Because of this promising future,
much of the discussion and guidance in this chapter may
one day become irrelevant. As helicopters integrate more
into the National Airspace System, the IFR infrastructure
and instrument training will become more prevalent. In the
future, UIMC may no longer be the emergency that ends
with a fatality but rather associated with proper prevention,
skilled recovery techniques along with the aid of emerging
new life saving avionics technology. A helicopter instrument
rating may be a life-saving addition to a pilot’s level of
certification. Please refer to the Instrument Flying Handbook
(FAA-H-8083-15, as revised); Advanced Avionics Handbook
(FAA-H-8083-6, as revised); and the Pilot’s Handbook of
Aeronautical Knowledge (FAA-H-8083-25, as revised) for
further exploration of IFR operations and how to obtain an
instrument rating.
When faced with deteriorating weather, planning and
prevention, not recovery, are the best strategies to eliminate
UIMC-related accidents and fatalities.
11-27
Emergency Equipment and Survival Gear
Both Canada and Alaska require pilots to carry survival
gear. Always carry survival gear when flying over rugged
and desolate terrain. The items suggested in Figure 11-12
are both weather and terrain dependent. The pilot also needs
to consider how much storage space the helicopter has and
how the equipment being carried affects the overall weight
and balance of the helicopter.
Chapter Summary
Emergencies should always be anticipated. Knowledge
of the helicopter, possible malfunctions and failures, and
methods of recovery can help the pilot avoid accidents and
be a safer pilot. Helicopter pilots should always expect the
worse hazards and possible aerodynamic effects and plan for
a safe exit path or procedure to compensate for the hazard.
12-1
Introduction
Pilots rely more on vision than on any other sense to orient
themselves in flight. The following visual factors contribute
to flying performance: good depth perception for safe
landings, good visual acuity to identify terrain features and
obstacles in the flightpath, and good color vision. Although
vision is the most accurate and reliable sense, visual cues can
be misleading, contributing to incidents occurring within the
flight environment. Pilots should be aware of and know how
to compensate effectively for the following:
• Physical deficiency or self-imposed stress, such as
smoking, which limits night-vision capability
• Visual cue deficiencies
• Limitations in visual acuity, dark adaptation, and color
and depth perception
For example, at night, the unaided eye has degraded visual
acuity. For more information on night operations, reference
Chapter 17, Aeromedical Factors, of the Pilot’s Handbook
of Aeronautical Knowledge (FAA-H-8083-25, as revised).
Night Operations
Chapter 12
12-2
Figure 12-1. Effects of dimming cockpit lighting during night flight
to better see surrounding terrain.
Visual Deficiencies
Night Myopia
At night, blue wavelengths of light prevail in the visible
portion of the spectrum. Therefore, slightly nearsighted
(myopic) individuals viewing blue-green light at night may
experience blurred vision. Even pilots with perfect vision find
that image sharpness decreases as pupil diameter increases.
For individuals with mild refractive errors, these factors
combine to make vision unacceptably blurred unless they
wear corrective glasses. Another factor to consider is “dark
focus.” When light levels decrease, the focusing mechanism
of the eye may move toward a resting position and make the
eye more myopic. These factors become important when
pilots rely on terrain features during unaided night flights.
Practicing good light discipline is very important and helps
pilots to retain their night adaptation. Keeping the cockpit
lighting on dim allows the pilot to better identify outside
details, unmarked hazards such as towers less than 200'
AGL, and unimproved landing sites with no hazard lighting.
A simple exercise that shows the effect of high versus low
light contrast would be to go out to a very dark road and
turn the dash board lights down very low or off and let your
eyes adjust to the ambient light level. Then, turn the dash
board lights up and note how the outside features disappear.
The same concept applies to cockpit lighting and being able
to see the surrounding terrain and obstacles. [Figure 12-1]
Special corrective lenses can be prescribed to pilots who
experience night myopia.
The eye automatically adjusts for the light level experienced.
During night flight, the cockpit and instrument lights should
be as dim as possible. The eye can then adjust for the outside
lighting conditions (ambient lighting) to see outside. The
dimmer the inside lighting is, the better you can see outside.
Hyperopia
Hyperopia is also caused by an error in refraction. In a
hyperopic state, when a pilot views a near image, the actual
focal point of the eye is behind the retinal plane (wall),
causing blurred vision. Objects that are nearby are not seen
clearly; only more distant objects are in focus. This problem,
is referred to as farsightedness.
Astigmatism
An unequal curvature of the cornea or lens of the eye causes
this condition. A ray of light is spread over a diffused area
in one meridian. In normal vision, a ray of light is sharply
focused on the retina. Astigmatism is the inability to
focus different meridians simultaneously. If, for example,
astigmatic individuals focus on power poles (vertical),
the wires (horizontal) are out of focus for most of them.
[Figure 12-2]
Presbyopia
This condition is part of the normal aging process, which
causes the lens to harden. Beginning in the early teens, the
human eye gradually loses the ability to accommodate for
and focus on nearby objects. When people are about 40 years
old, their eyes are unable to focus at normal reading distances
without reading glasses. Reduced illumination interferes with
focus depth and accommodation ability. Hardening of the lens
may also result in clouding of the lens (cataract formation).
Aviators with early cataracts may see a standard eye chart
clearly under normal daylight but have difficulty seeing under
bright light conditions. This problem is due to light scattering
as it enters the eye. This glare sensitivity is disabling under
certain circumstances. Glare disability, related to contrast
sensitivity, is the ability to detect objects against varying
shades of backgrounds. Other visual functions decline with
age and affect the aircrew member’s performance:
• Dynamic acuity
• Recovery from glare
• Function under low illumination
• Information processing
Vision in Flight
The visual sense is especially important in collision
avoidance and depth perception. Due to the structure of the
human eye, illusions and blindspots occur. The more pilots
understand the eye and how it functions, the easier it is to
compensate for these illusions and blindspots. Figure 12-3
shows the basic anatomy of the human eye and how it is like
12-3
Normal view Astigmatic view
The rods and
cones (film) of
the retina are
the receptors
which record
the image and
transmit it
through the
optic nerve to
the brain for
interpretation.
Rods and
cones
Fovea
(All Cones)
The pupil (aperture) is the opening at
the center of the iris. The size of the
pupil is adjusted to control the amount
of light entering the eye.
PUPIL
Light passes through the cornea (the
transparent window on the front of the
eye) and then through the lens to
focus on the retina.
CORNEA
Iris
Retina
Lens
Optic nerve
Rod concentration
Figure 12-2. Example of a view that might be experienced by someone with astigmatism.
Figure 12-3. The human eye.
Visual Acuity
Normal visual acuity, or sharpness, is 20/20. A value of
20/80 indicates that an individual reads at 20 feet the letters
that an individual with normal acuity (20/20) reads at 80
feet away. The human eye functions like a camera. It has
a camera. A camera is able to focus on near and far objects
by changing the distance between the lens and the film.
With the eye on the other hand, objects can be seen clearly
at various distances because the shape of its lens is changed
automatically by small muscles.
12-4
Once a target is detected in the peripheral
field of dark-adapted vision, aircrews
maintain continual surveillance by using
the off-center vision technique. They look
10 degrees above, below, or to either side
of the target, viewing it no longer than two
to three seconds at each position.
Observer
FOCAL POINTS
X
10°
10°
X
X 10° X 10°
Figure 12-4. Off-center vision technique.
an instantaneous field of view, which is oval and typically
measures 120° vertically by 150° horizontally. When both
eyes are used for viewing, the overall field of vision measures
about 120° vertically by 200° horizontally.
The Eye
Vision is primarily the result of light striking a photosensitive
layer, called the retina, at the back of the eye. The retina is
composed of light-sensitive cones and rods. The cones in the
eye perceive an image best when the light is bright, while the
rods work best in low light. The pattern of light that strikes
the cones and rods is transmitted as electrical impulses by the
optic nerve to the brain where these signals are interpreted
as an image.
Cones
Cones are concentrated around the center of the retina. They
gradually diminish in number as the distance from the center
increases. Cones allow color perception by sensing red, blue,
and green light. Directly behind the lens, on the retina, is
a small, notched area called the fovea. This area contains
only a high concentration of cone receptors. The best vision
in daylight is obtained by looking directly at the object.
This focuses the image on the fovea, where detail is best
seen. The cones, however, do not function well in darkness,
which explains why color is not seen as vividly at night as
it is during the day.
Rods
Concentrated outside the fovea area, the rods are the dim
light and night receptors. The number of rods increases as the
distance from the fovea increases. Rods sense images only
in black and white. Because the rods are not located directly
behind the pupil, they are responsible for most peripheral
vision. Images that move are perceived more easily by the
rod areas than by the cones in the fovea. If you have ever
seen something move out of the corner of your eye, it was
most likely detected by rod receptors.
In low light, the cones lose much of their function, while
rods become more receptive. The eye sacrifices sharpness for
sensitivity. The ability to see an object directly in front of you is
reduced, and much depth perception is lost, as well as judgment
of size. The concentration of cones in the fovea can make a
night blindspot at the center of vision. How well a person sees
at night is determined by the rods in the eyes, as well as by the
amount of light allowed into the eyes. At night, the wider the
pupil is open at night, the better night vision becomes.
Night Vision
Diet and general physical health have an impact on how well
a person can see in the dark. Deficiencies in vitamins A and C
have been shown to reduce night acuity. Other factors, such
as carbon monoxide poisoning, smoking, alcohol, and certain
drugs can greatly decrease night vision. Lack of oxygen can
also decrease night vision as the eye requires more oxygen
per unit weight than any other part of the body.
Night Scanning
Good night visual acuity is needed for collision avoidance.
Night scanning, like day scanning, uses a series of short,
regularly spaced eye movements in 10° sectors. Unlike day
scanning, however, off-center viewing is used to focus objects
on the rods rather than the fovea blindspot. [Figure 12-4] When
looking at an object, avoid staring at it too long. If staring
at an object without moving the eyes, the retina becomes
accustomed to the light intensity and the image begins to
fade. To keep it clearly visible, new areas in the retina must
be exposed to the image. Small, circular eye movements help
eliminate the fading. Also, move the eyes more slowly from
sector to sector than during the day to prevent blurring.
During daylight, objects can be perceived at a great distance
with good detail. At night, range is limited, and detail is poor.
Objects along the flight path can be more readily identified at
night, by using the proper techniques to scan the terrain. To
12-5
4
2
3
1
10°
6 seconds
6 seconds
6 seconds
6 seconds
6 seconds 3 seconds
3 seconds 3 seconds 3 seconds
3 seconds 3 seconds
4 seconds 4 seconds
4 seconds
4 seconds
Figure 12-5. Scanning pattern.
Figure 12-6. Night vision.
scan effectively, pilots look from side to side. They should
begin scanning at the greatest distance at which an object
can be perceived high on the horizon, thence moving inward
toward the position of the aircraft. Figure 12-5 shows this
scanning pattern. Because the light-sensitive elements of
the retina are unable to perceive images that are in motion, a
stop-turn-stop-turn motion should be used. For each stop, an
area about 30 degrees wide should be scanned. This viewing
angle includes an area about 250 meters wide at a distance of
500 meters. The duration of each stop is based on the degree
of detail that is required, but no stop should last more than
two or three seconds. When moving from one viewing point
to the next, pilots should overlap the previous field of view
by 10 degrees. This scanning technique allows greater clarity
in observing the periphery. Other scanning techniques, as
illustrated in Figure 12-6, may be developed to fit the situation.
Obstruction Detection
Obstructions having poor reflective surfaces, such as wires
and small tree limbs, are difficult to detect. The best way to
12-6
Figure 12-7. Aircraft position lights.
locate wires is by looking for the support structures. However,
pilots should review the most current hazard maps with
known wire locations before night flights.
Aircraft Lighting
In order to see other aircraft more clearly, regulations require
that all aircraft operating during the night hours have special
lights and equipment. The requirements for operating at night
are found in Title 14 of the Code of Federal Regulations (14
CFR) part 91. In addition to aircraft lighting, the regulations
also provide a definition of night flight in accordance with
14 CFR part 91, currency requirements, fuel reserves, and
necessary electrical systems.
Position lights enable a pilot to locate another aircraft, as
well as help determine its direction of flight. The approved
aircraft lights for night operations are a green light on the
right cabin side or wingtip, a red light on the left cabin side
or wingtip, and a white position light on the tail. In addition,
flashing aviation red or white anticollision lights are required
for all flights, if equipped on the aircraft and in an operable
condition (in accordance with 14 CFR Section 91.209(b),
which aids in the identification during night conditions).
These flashing lights can be in a number of locations but are
most commonly found on the top and bottom of the cabin.
Figure 12-7 shows examples of aircraft lighting. By
interpreting the position lights on other aircraft, the pilot in
aircraft 3 can determine whether the aircraft is flying in the
opposite direction or is on a collision course. If a red position
light is seen to the right of a green light, such as shown by
aircraft 1, it is flying toward aircraft 3. A pilot should watch
this aircraft closely and be ready to change course. Aircraft 2,
on the other hand, is flying away from aircraft 3, as indicated
by the white position light.
Visual Illusions
Illusions give false impressions or misconceptions of actual
conditions; therefore, pilots must understand the type of
illusions that can occur and the resulting disorientation.
Although the eye is the most reliable of the senses, some
illusions can result from misinterpreting what is seen; what
is perceived is not always accurate. Even with the references
outside the cockpit and the display of instruments inside,
pilots must be on guard to interpret information correctly.
Relative-Motion Illusion
Relative motion is the falsely perceived self-motion in
relation to the motion of another object. The most common
example is as follows. An individual in a car is stopped at a
traffic light and another car pulls alongside. The individual
who was stopped at the light perceives the forward motion
of the second car as his or her own motion rearward. This
results in the individual applying more pressure to the brakes
unnecessarily. This illusion can be encountered during flight
in situations such as formation flight, hover taxi, or hovering
over water or tall grass.
Confusion with Ground Lights
Confusion with ground lights occurs when a pilot mistakes
ground lights for stars. The pilot can place the helicopter
in an extremely dangerous flight attitude if he or she aligns
it with the wrong lights. In Figure 12-8A, the helicopter is
aligned with a road and not with the horizon. Isolated ground
lights can appear as stars and could lead to the illusion that
the helicopter is in a nose-high attitude.
When no stars are visible because of overcast conditions,
unlighted areas of terrain can blend with the dark overcast to
create the illusion that the unlighted terrain is part of the sky
in Figure 12-8B. In this illusion, the shoreline is mistaken for
the horizon. In an attempt to correct for the apparent nose-
high attitude, a pilot may lower the collective and attempt
to fly “beneath the shore.” This illusion can be avoided by
referencing the flight instruments and establishing a true
horizon and attitude.
Reversible Perspective Illusion
At night, an aircraft or helicopter may appear to be moving
away when it is actually approaching. If the pilot of each
aircraft has the same assumption, and the rate of closure
is significant, by the time each pilot realizes his or her
own error in assumption, it may be too late to avoid a
mishap. This illusion is called reversible perspective and
is often experienced when a pilot observes another aircraft
12-7
A
Perceived Horizon
(ground lights)
Actual Horizon
A O M
CLUTCH MR
TEMP
MR
CHIP
STARTER
ON
TR
CHIP
lOW
FUEL
LOW
RPM
N
E
W
333
24
12
30
6
GS
15
20
I0
0
I0
15
VERTICAL SPEED
100 FEET PER MINUTE
UP
DOWN
5
5
33
3024
2I
I5
I2 6
3
2 MIN TURN
DC ELEC
L R
30.0
29.929.8
I00 FEET
I
456
7
9
2
0
8
3
CALIBRATED
TO
20,000 FEET
ALT
20 20
I0 I0
I0 I0
20 20
TESTSTBY PWR
IN Hg
ALg.
MANFOLD
PRESS
25
5
15
30
20
10
35
25
5
15
30
20
10
35
20 30
40
50
6070
80
90
100
0 10
MPH
KNOTS
120
110
100
90 80 70
60
50
40
3020
110
100
90
80
70
60
50
110
100
90
80
70
60
50
E R
%RPM
20 20
I0 I0
I0 I0
20 20
TESTSTBY PWR
B
Perceived Horizon
(shore line)
Actual Horizon
(overcast sky)
A O M
CLUTCH MR
TEMP
MR
CHIP
STARTER
ON
TR
CHIP
lOW
FUEL
LOW
RPM
N
E
W
333
24
12
30
6
GS
15
20
I0
0
I0
15
VERTICAL SPEED
100 FEET PER MINUTE
UP
DOWN
5
5
33
3024
2I
I5
I2 6
3
2 MIN TURN
DC ELEC
L R
30.0
29.929.8
I00 FEET
I
456
7
9
2
0
8
3
CALIBRATED
TO
20,000 FEET
ALT
20 20
I0 I0
I0 I0
20 20
TESTSTBY PWR
IN Hg
ALg.
MANFOLD
PRESS
25
5
15
30
20
10
35
25
5
15
30
20
10
35
20 30
40
50
6070
80
90
100
0 10
MPH
KNOTS
120
110
100
90 80 70
60
50
40
3020
110
100
90
80
70
60
50
110
100
90
80
70
60
50
E R
%RPM
20 20
I0 I0
I0 I0
20 20
TESTSTBY PWR
Figure 12-8. At night, the horizon may be hard to discern due to dark terrain and misleading light patterns on the ground.
or helicopter flying an approaching, parallel course. To
determine the direction of flight, the pilot should observe the
other aircraft’s position lights. Remember the following: red
on right returning; that is, if an aircraft is seen with the red
position light on the right and the green position light on the
left, the observed aircraft is traveling in the opposite direction.
Flicker Vertigo
Flicker vertigo is technically not an illusion; however, as
most people are aware from personal experience, viewing
a flickering light can be both distracting and annoying.
Flicker vertigo may be created by helicopter rotor blades or
airplane propellers interrupting direct sunlight at a rate of 4
to 20 cycles per second. Flashing anticollision strobe lights,
especially while the aircraft is in the clouds, can also produce
this effect. One should also be aware that photic stimuli at
certain frequencies could produce seizures in those rare
individuals who are susceptible to flicker-induced epilepsy.
Night Flight
The night flying environment and the techniques used when
flying at night depend on outside conditions. Flying on a
bright, clear, moonlit evening when the visibility is good, and
the wind is calm is not much different from flying during the
day. However, if flying on an overcast night over a sparsely
populated area, with few or no outside lights on the ground,
the situation is quite different. Visibility is restricted, so be
more alert in steering clear of obstructions and low clouds.
Options are also limited in the event of an emergency, as it
is more difficult to find a place to land and determine wind
direction and speed. At night, rely more heavily on the aircraft
systems, such as lights, flight instruments, and navigation
equipment. As a precaution, if visibility is limited or outside
references are inadequate, strongly consider delaying the
flight until conditions improve, unless proper instrument
flight training has been received and the helicopter has the
appropriate instrumentation and equipment.
Preflight
Aircraft preflight inspection is a critical aspect of flight
safety. It must comply with the appropriate rotorcraft flight
manual (RFM). Preflight should be scheduled as early as
possible in the flight planning sequence, preferably during
daylight hours, allowing time for maintenance assistance and
correction. If a night preflight is necessary, a flashlight with
an unfiltered lens (white light) should be used to supplement
lighting. Oil and hydraulic fluid levels and leaks are difficult
to detect with a blue-green or red lens. Windscreens should
be checked to ensure they are clean and relatively free of
scratches. Slight scratches are acceptable for day flight but
may not be for night flight. The search light or landing light
should be positioned for the best possible illumination during
an emergency descent.
Careful attention must be paid to the aircraft electrical system.
In helicopters equipped with fuses, a spare set is required
by regulation, and by common sense, so make sure they are
on board. If the helicopter is equipped with circuit breakers,
check to see that they are not tripped. A tripped circuit breaker
may be an indication of an equipment malfunction and should
be left for maintenance to troubleshoot before flying.
All aircraft operating between sunset and sunrise are required
to have operable navigation (position) lights. Turn these lights
on during the preflight to inspect them visually for proper
operation. Between sunset and sunrise, these lights must be
on any time the helicopter is operating.
12-8
All recently manufactured aircraft certificated for night
flight must have an anticollision light that makes the aircraft
more visible to other pilots. This light is either a red or white
flashing light and may be in the form of a rotating beacon
or a strobe. While anticollision lights are required for night
visual flight rules (VFR) flights, they may be turned off any
time they create a distraction for the pilot.
One of the first steps in preparation for night flight is to
become thoroughly familiar with the helicopter’s cockpit,
instrumentation, and control layout. It is recommended that
a pilot practice locating each instrument, control, and switch,
both with and without cabin lights. Since the markings on
some switches and circuit breaker panels may be difficult
to read at night, be able to locate and use these devices, and
read the markings in poor light conditions. Before starting
the engine, make sure all necessary equipment and supplies
needed for the flight, such as charts, notepads, and flashlights,
are accessible and ready for use.
Cockpit Lights
Check all interior lights with special attention to the instrument
and panel lights. The panel lighting can usually be controlled
with a rheostat or dimmer switch, allowing the pilot to adjust
the intensity. If a particular light is too bright or causes
reflection or glare off the windshield, it should be adjusted or
turned off. As ambient light level decreases from twilight to
darkness, intensity of the cockpit lights is reduced to a low,
usable intensity level that reduces any glare or reflection off
the windshield. The light level should be adjusted to as close
to the ambient light level as possible. A flashlight, with red or
blue-green lens filter, or map light can supplement the available
light in the cockpit. Always carry a flashlight with fresh
batteries to provide an alternate source of light if the interior
lights malfunction. If an existing map/utility light is used, it
should be hand-held or remounted to a convenient location.
In order to retain night adaptation, use low level light when
using your checklist. Brief your passengers on the importance
of light discipline during night flight so the pilot is not blinded,
causing loss of dark adaptation.
Engine Starting and Rotor Engagement
Use extra caution when starting the engine and engaging the
rotors, especially in dark areas with little or no outside lights.
In addition to the usual call of “clear,” turn on the position
and anticollision lights. If conditions permit, also turn the
landing light on momentarily to help warn others that the
engine is about to start and engage the rotors.
Taxi Technique
Landing lights usually cast a beam that is narrow and
concentrated ahead of the helicopter, so illumination to the
side is minimal. Therefore, slow the taxi at night, especially
in congested ramp and parking areas. Some helicopters have
a hover light in addition to a landing light, which illuminates
a larger area under the helicopter.
When operating at an unfamiliar airport at night, ask for
instructions or advice concerning local conditions, so as to
avoid taxiing into areas of construction, or unlighted, unmarked
obstructions. Ground controllers or UNICOM operators are
usually cooperative in furnishing this type of information.
Night Traffic Patterns
Traffic patterns are covered in Chapter 9, Basic Flight
Maneuvers, but the following additional considerations
should be taken into account when flying a helicopter in a
night traffic pattern:
1. The minimum recommended pattern height at night
is 1,000 feet when able.
2. If possible, consider taking the right hand night pattern
with fixed wing in the left hand pattern for extra
separation, but if needed, conform and integrate with
the fixed wing using the same pattern height.
3. Be extra vigilant on abiding with noise abatement
procedures at night.
4. Always plan to use the lit runway at night for
unaided (no night vision equipment) approaches and
departures.
5. Avoid downwind and crosswind approaches at night
when able.
Takeoff
Before takeoff, make sure that there is a clear, unobstructed
takeoff path. At airports, this is accomplished by taking
off over a runway or taxi way, however, if operating off-
airport, pay more attention to the surroundings. Obstructions
may also be difficult to see if taking off from an unlighted
area. Once a suitable takeoff path is chosen, select a point
down the takeoff path to use for directional reference. The
landing light should be positioned in order to illuminate
the tallest obstacles in the takeoff path. During a night
takeoff, notice a lack of reliable outside visual references
after becoming airborne. This is particularly true at small
airports and off-airport landing sites located in sparsely
populated areas. To compensate for the lack of outside
references, use the available flight instruments as an aid.
Check the altimeter and the airspeed indicator to verify the
proper climb attitude. An attitude indicator, if installed, can
enhance attitude reference.
The first 500 feet of altitude after takeoff is considered to be
the most critical period in transitioning from the comparatively
well-lit airport or heliport into what sometimes appears to be
12-9
total darkness. A takeoff at night is usually an “altitude over
airspeed” maneuver, meaning a pilot most likely performs
a nearly maximum performance takeoff. This improves the
chances for obstacle clearance and enhances safety.
En Route Procedures
In order to provide a higher margin of safety, it is
recommended that a cruising altitude somewhat higher than
normal be selected. There are three reasons for this. First,
a higher altitude gives more clearance between obstacles,
especially those that are difficult to see at night, such as high-
tension wires and unlighted towers. Second, in the event of
an engine failure, there is more time to set up for a landing
and the greater gliding distance gives more options for a safe
landing. Third, radio reception is improved, particularly if
using radio aids for navigation.
During preflight planning, when possible, it is recommended
that a route of flight be selected that is within reach of an
airport, or any safe landing site. It is also recommended
that pilots fly as close as possible to a populated or lighted
area, such as a highway or town. Not only does this offer
more options in the event of an emergency, but also makes
navigation a lot easier. A course comprised of a series of
slight zigzags to stay close to suitable landing sites and
well-lit areas, only adds a little more time and distance to an
otherwise straight course.
In the event of a forced landing at night, use the same
procedure recommended for day time emergency landings.
If available, turn on the landing light during the final descent
to help in avoiding obstacles along the approach path.
Collision Avoidance at Night
Because the quantity and quality of outside visual references
are greatly reduced, a pilot tends to focus on a single point
or instrument, making him or her less aware of the other
traffic around. Make a special effort to devote enough time
to scan for traffic. As discussed previously in this chapter,
effective scanning is accomplished with a series of short,
regularly spaced eye movements that bring successive
areas of the sky into the central visual field. Contrary to
the 30-degree scan used to view the ground in the case of
scanning for other aircraft, each movement in this case
should not exceed 10 degrees, and each area should be
observed for at least 1 second to enable detection. If the
pilot detects a dimly lit object in a certain direction, the
pilot should not look directly at the object, but scan the area
adjacent to it, called off-center viewing. This will decrease
the chances of fixating on the light and allow focusing more
on the objects (e.g., tower, aircraft, ground lights). Short
stops of a few seconds in duration in each scan will help to
detect the light and its movement. A pilot can determine
another aircraft’s direction of flight by interpreting the
position and anticollision lights, as previously described.
When scanning, pilots should also remember to move their
heads, not just their eyes. Ground obstructions can cover
a considerable amount of sky, and the area can easily be
uncovered by a small head movement.
Approach and Landing
Night approaches and landings do have some advantages over
daytime approaches, as the air is generally smoother, and the
disruptive effects of turbulence and excessive crosswinds are
often absent. However, there are a few special considerations
and techniques that apply to approaches at night. For
example, when landing at night, especially at an unfamiliar
airport, make the approach to a lighted runway and then use
the taxiways to avoid unlighted obstructions or equipment.
Carefully controlled studies have revealed that pilots have a
tendency to make lower approaches at night than during the
day. This is potentially dangerous as there is a greater chance
of hitting an obstacle, such as an overhead wire or fence, that is
difficult to see. It is good practice to make steeper approaches at
night, increasing the probability of clearing obstacles. Monitor
altitude and rate of descent using the altimeter.
Another pilot tendency during night flight is to focus too
much on the landing area and not pay enough attention to
airspeed. If too much airspeed is lost, a vortex ring state
condition may result. Maintain the proper attitude during
the approach, and ensure that you keep some forward
airspeed and movement until close to the ground. Outside
visual references for airspeed and rate of closure may not be
available, especially when landing in an unlit area, so pay
special attention to the airspeed indicator.
Although the landing light is a helpful aid when making
night approaches, there is an inherent disadvantage. The
portion of the landing area illuminated by the landing light
seems higher than the dark area surrounding it. This effect
can cause a pilot to terminate the approach at an altitude that
is too high, which may result in a vortex ring state condition
and a hard landing.
Illusions Leading to Landing Errors
Various surface features and atmospheric conditions
encountered in night landing can create illusions of incorrect
height above and distance from the runway threshold.
Landing errors from these illusions can be prevented by
anticipating them during approaches, conducting an aerial
visual inspection of unfamiliar airports before landing, using
electronic glideslope or VASI systems when available, and
maintaining optimum proficiency in landing procedures.
12-10
Featureless Terrain Illusion
An absence of ground features, as when landing over water,
darkened areas, and terrain made featureless by snow, can
create the illusion that the aircraft is at a higher altitude than
it actually is. The pilot who does not recognize this illusion
will fly a lower approach.
Atmospheric Illusions
Rain on the windscreen can create the illusion of greater
height, and atmospheric haze can create the illusion of being
at a greater distance from the runway. The pilot who does not
recognize these illusions flies a higher approach. Penetration
of fog can create the illusion of pitching up. The pilot who
does not recognize this illusion steepens the approach, often
quite abruptly.
Ground Lighting Illusions
Lights along a straight path can be mistaken for runway
and approach lights. This might include street lights along a
roadside or even the internal lights of a moving train. Another
illusion may occur with very intense runway and approach
lighting. Due to the relative brightness of these lights, the
pilot may perceive them to be closer than they really are.
Assuming that the lights are as close as they appear, the
pilot may attempt an approach that is actually lower than
glideslope. Conversely, the pilot flying over terrain with few
lights may make a lower than normal approach.
Helicopter Night VFR Operations
While ceiling and visibility significantly affect safety in night
VFR operations, lighting conditions also have a profound
effect on safety. Even in conditions in which visibility and
ceiling are determined to be visual meteorological conditions,
the ability to discern unlit or low contrast objects and terrain
at night may be compromised. The ability to discern these
objects and terrain is referred to as the “seeing condition,”
and is related to the amount of natural and man-made
lighting available, and the contrast, reflectivity, and texture
of surface terrain and obstruction features. In order to conduct
operations safely, seeing conditions must be accounted for in
the planning and execution of night VFR operations.
Night VFR seeing conditions can be described by identifying
high lighting conditions and low lighting conditions.
High lighting conditions exist when one of two sets of
conditions are present:
1. The sky cover is less than broken (less than 5⁄8 cloud
cover), the time is between the local moon rise and
moon set, and the lunar disk is at least 50 percent
illuminated; or
2. The aircraft is operated over surface lighting that, at
least, provides lighting of prominent obstacles, the
identification of terrain features (shorelines, valleys,
hills, mountains, slopes) and a horizontal reference
by which the pilot may control the helicopter. For
example, this surface lighting may be the result of:
a. Extensive cultural lighting (manmade, such as a
built-up area of a city),
b. Significant reflected cultural lighting (such as the
illumination caused by the reflection of a major
metropolitan area’s lighting reflecting off a cloud
ceiling), or
c. Limited cultural lighting combined with a
high level of natural reflectivity of celestial
illumination, such as that provided by a surface
covered by snow or a desert surface.
Low lighting conditions are those that do not meet the high
lighting conditions requirements.
Some areas may be considered a high lighting environment
only in specific circumstances. For example, some surfaces,
such as a forest with limited cultural lighting, normally
have little reflectivity, requiring dependence on significant
moonlight to achieve a high lighting condition. However,
when that same forest is covered with snow, its reflectivity
may support a high lighting condition based only on starlight.
Similarly, a desolate area, with little cultural lighting, such as
a desert, may have such inherent natural reflectivity that it
may be considered a high lighting conditions area regardless
of season, provided the cloud cover does not prevent starlight
from being reflected from the surface. Other surfaces, such
as areas of open water, may never have enough reflectivity or
cultural lighting to ever be characterized as a high lighting area.
Through the accumulation of night flying experience in a
particular area, the pilot develops the ability to determine,
prior to departure, which areas can be considered supporting
high or low lighting conditions. Without that pilot experience,
low lighting considerations should be applied by pilots for
both preflight planning and operations until high lighting
conditions are observed or determined to be regularly
available. Even if the aircraft is certified for day and night
VFR conditions, night flight should only be conducted if
adequate celestial illumination is assured during the entirety
of the flight.
Chapter Summary
Knowledge of the basic anatomy and physiology of the eye
is helpful in the study of helicopter night operations. Adding
12-11
to that knowledge a study of visual illusions gives the pilot
ways to overcome those illusions. Techniques for preflight,
engine start-up, collision avoidance, and night approach and
landings help teach the pilot safer ways to conduct flight at
night. More detailed information on the subjects discussed
in this chapter is available in the Aeronautical Information
Manual (AIM) and online at www.faa.gov.
12-12
13-1
Introduction
The accident rate for helicopters has traditionally been higher
than the accident rate of fixed-wing aircraft, probably due to
the helicopter’s unique capabilities to fly and land in more
diverse situations than fixed-wing aircraft and pilot attempts
to fly the helicopter beyond the limits of his or her abilities or
beyond the capabilities of the helicopter. With no significant
improvement in helicopter accident rates for the last 20 years,
the Federal Aviation Administration (FAA) has joined with
various members of the helicopter community to improve
the safety of helicopter operations.
According to National Transportation Safety Board (NTSB)
statistics, approximately 80 percent of all aviation accidents
are caused by pilot error, the human factor. Many of
these accidents are the result of the failure of instructors
to incorporate single-pilot resource management (SRM)
and risk management into flight training instruction of
aeronautical decision-making (ADM).
SRM is defined as the art of managing all the resources (both
on board the aircraft and from outside sources) available to a
pilot prior to and during flight to ensure a successful flight.
When properly applied, SRM is a key component of ADM.
Additional discussion includes integral topics such as, the
concepts of risk management, workload or task management,
situational awareness, controlled flight into terrain (CFIT)
awareness, and automation management.
Effective Aeronautical
Decision-Making
Chapter 13
13-2
Preflight
Takeoff
Cruise
Approach & Landing
Time
Task Load
High
Low
Pilot Capabilities
Task Requirements
Figure 13-1. The pilot has a limited capacity of doing work and handling tasks, meaning there is a point at which the tasking exceeds
the pilot’s capability. When this happens, either tasks are not done properly or some are not done at all.
ADM is all about learning how to gather information, analyze
it, and make decisions. It helps the pilot accurately assess
and manage risk and make accurate and timely decisions.
Although the flight is coordinated by a single person, the
use of available resources, such as air traffic control (ATC)
and flight service stations (FSS)/automated flight service
stations (AFSS), replicates the principles of crew resource
management (CRM) (see page 14-7).
References on SRM and ADM include:
• FAA-H-8083-2, Risk Management Handbook.
• Aeronautical Information Manual (AIM).
• Advisory Circular (AC) 60-22, Aeronautical Decision
Making, which provides background information
about ADM training in the general aviation (GA)
environment.
• FAA-H-8083-25, Pilot’s Handbook of Aeronautical
Knowledge.
Aeronautical Decision-Making (ADM)
Making good choices sounds easy enough. However,
there are a multitude of factors that come into play when
these choices, and subsequent decisions, are made in the
aeronautical world. Many tools are available for pilots to
become more self-aware and assess the options available,
along with the impact of their decision. Yet, with all the
available resources, accident rates are not being reduced. Poor
decisions continue to be made, frequently resulting in lives
being lost and/or aircraft damaged or destroyed. The Risk
Management Handbook discusses ADM and SRM in detail
and should be thoroughly read and understood.
While progress is continually being made in the advancement
of pilot training methods, aircraft equipment and systems, and
services for pilots, accidents still occur. Historically, the term
“pilot error” has been used to describe the causes of these
accidents. Pilot error means an action or decision made by
the pilot was the cause of, or a contributing factor that led to,
the accident. This definition also includes the pilot’s failure to
make a decision or take action. From a broader perspective,
the phrase “human factors related” more aptly describes these
accidents since it is usually not a single decision that leads
to an accident, but a chain of events triggered by a number
of factors. [Figure 13-1]
The poor judgment chain, sometimes referred to as the
“error chain,” is a term used to describe this concept of
contributing factors in a human factors related accident.
Breaking one link in the chain is often the only event
necessary to change the outcome of the sequence of
events. The following is an example of the type of scenario
illustrating the poor judgment chain.
Scenario
A Helicopter Air Ambulance (HAA) pilot is nearing the end
of his shift when he receives a request for a patient pickup
at a roadside vehicle accident. The pilot has started to feel
the onset of a cold; his thoughts are on getting home and
getting a good night’s sleep. After receiving the request, the
pilot checks the accident location and required flightpath
to determine if he has time to complete the flight to the
scene, then on to the hospital before his shift expires. The
pilot checks the weather and determines that, although
thunderstorms are approaching, the flight can be completed
prior to their arrival.
13-3
The pilot and on-board medical crews depart the home
location and arrive overhead, at the scene of the vehicular
accident. The pilot is not comfortable with the selected
landing area due to tall trees in all quadrants of the confined
area. The pilot searches for a secondary landing area. Unable
to find one nearby, the pilot then returns to the initial landing
area and decides he can make it work.
After successfully landing the aircraft, he is told that there
will be a delay before the patient is loaded because more time
is needed to extricate the patient from the wreckage. Knowing
his shift is nearly over, the pilot begins to feel pressured to
“hurry up” or he will require an extension for his duty day.
After 30 minutes, the patient is loaded, and the pilot ensures
everyone is secure. He notes that the storm is now nearby and
that winds have picked up considerably. The pilot thinks, “No
turning back now, the patient is on board and I’m running out
of time.” The pilot knows he must take off almost vertically
to clear the obstacles and chooses his departure path based
on the observed wind during landing. Moments later, prior to
clearing the obstacles, the aircraft begins an uncontrollable
spin and augers back to the ground, seriously injuring all on
board and destroying the aircraft.
What could the pilot have done differently to break this
error chain? More important—what would you have done
differently? By discussing the events that led to this accident,
you should develop an understanding of how a series of
judgmental errors contributed to the final outcome of this flight.
For example, the pilot’s decision to fly the aircraft knowing
that the effects of an illness were present was the initial
contributing factor. The pilot was aware of his illness, but,
was he aware of the impact of the symptoms—fatigue,
general uneasy feeling due to a slight fever, perhaps?
Next, knowing the shift was about to end, the pilot based his
time required to complete the flight on ideal conditions, and
did not take into consideration the possibility of delays. This
led to a feeling of being time limited.
Even after determining the landing area was unsuitable, the
pilot forced the landing due to time constraints. At any time
during this sequence, the pilot could have aborted the flight
rather than risk crew lives. Instead, the pilot became blinded
by a determination to continue.
After landing, and waiting 30 minutes longer than planned,
the pilot observed the outer effects of the thunderstorm, yet
still attempted to depart. The pilot dispelled any available
options by thinking the only option was to go forward;
however, it would have been safer to discontinue the flight.
Using the same departure path selected under different wind
conditions, the pilot took off and encountered winds that
led to loss of aircraft control. Once again faced with a self-
imposed time constraint, the pilot improperly chose to depart
the confined area. The end result: instead of one patient to
transport by ground (had the pilot aborted the flight at any
point), there were four patients to be transported.
On numerous occasions leading to and during the flight, the
pilot could have made effective decisions that could have
prevented this accident. However, as the chain of events
unfolded, each poor decision left him with fewer options.
Making sound decisions is the key to preventing accidents.
Traditional pilot training emphasizes flying skills, knowledge
of the aircraft, and familiarity with regulations. SRM and
ADM training focus on the decision-making process and on
the factors that affect a pilot’s ability to make effective choices.
Trescott Tips
Max Trescott, Master Certificated Flight Instructor (CFI)
and Master Ground Instructor and winner of the 2008 CFI of
the year, has published numerous safety tips that every pilot
should heed. He believes that the word “probably” should
be purged from our flying vocabulary. Mr. Trescott contends
that “probably” means we’ve done an informal assessment
of the likelihood of an event occurring and have assigned a
probability to it. He believes the term implies that we believe
things are likely to work out, but there’s some reasonable
doubt in our mind. He further explains that if you ever think
that your course of action will “probably work out,” you
need to choose a new option that you know will work out.
Another safety tip details the importance of accumulating
flight hours in one specific airframe type. He explains that
“statistics have shown that accidents are correlated more with
the number of hours of experience a pilot has in a particular
aircraft model and not with his or her total number of flight
hours. Accidents tend to decrease after a pilot accumulates
at least 100 hours of experience in the aircraft he or she is
flying. Thus, when learning to fly, or when transitioning into
a new model, your goal should be to concentrate your flying
hours in that model.” He suggests waiting until you reach 100
hours of experience in one particular model before attempting
a dual rating with another model. In addition, if you only fly
a few hours per year, maximize your safety by concentrating
those hours in just one aircraft model.
The third safety tip that is well worth mentioning is what
Mr. Trescott calls “building experience from the armchair.”
Armchair flying is simply closing your eyes and mentally
practicing exactly what you do in the aircraft. This is an
excellent way to practice making radio calls, departures,
approaches and even visualizing the parts and pieces of the