Simply put, the pilot divides the length of an intended runway by 1.67 or 1.92, as appropriate, to determine the minimum distance that
should be available for landing. With this safety margin, it works out that the minimum dry runway field length should be at least 1.4
times the calculated air and ground distance needed, and the wet runway landing field length should be at least 1.61 times th e
calculated air and ground distance needed. Careful flight planning allows a pilot to determine how much load in terms of fuel ,
passengers, or cargo can be carried to a particular runway while still maintaining the desired safety margin. Depending on th e
destination, the load might need to be limited in order to protect the safety margin when landing. This is often complex, since fuel
load has its own safety implications.
Certified landing field length requirements are computed for the stop made with speed brakes deployed and maximum wheel braking.
Reverse thrust is not used in establishing the certified landing distances. However, reversers should definitely be used, if available.
Landing Speeds
As in the takeoff planning, there are certain speeds that should be taken into consideration when landing a jet airplane. The speeds are
as follows:
⦁ VSO —stall speed in the landing configuration.
⦁ VREF —1.3 times the stall speed in the landing configuration.
⦁ Approach climb—the speed that guarantees adequate performance in a go-around situation with an
inoperative engine.
⦁ Landing climb—the speed that guarantees adequate performance in arresting the descent and making a go-
around from the final stages of landing with the airplane in the full landing configuration and maximum
takeoff power available on all engines.
Pilots may need to perform traffic pattern takeoffs and landings. Pilots should use speeds recommended by the manufacturer while
maneuvering in the traffic pattern prior to slowing to the final approach target speed in relation to V REF. The speeds should be
calculated for every landing and posted where they are visible to both pilots.
The approach and landing sequence in a jet airplane should be accomplished in accordance with an approach and landing profile
developed for the particular airplane. [Figure 16-17]
Figure 16-17. Typical approach and landing profile.
Significant Differences
A safe approach in any type of airplane culminates in a particular position, speed, and height over the runway threshold. That final
flight condition is the target window at which the entire approach aims. Propeller-powered airplanes are able to approach that target
from wider angles, greater speed differentials, and a larger variety of glidepath angles. Jet airplanes are not as responsive to power
and course corrections, so the final approach should be more stable, more deliberate, and more constant in order to reach the window
accurately.
The transitioning pilot should understand that in spite of their impressive performance capabilities, there are many reasons why jet
airplanes are less forgiving than piston-engine airplanes during approaches and when correcting approach errors.
⦁ There is no propeller slipstream to produce immediate extra lift at constant airspeed. There is no such thing
as salvaging a misjudged glidepath with a sudden burst of power. Added lift can only be achieved by
accelerating the airframe.
⦁ Propeller slipstream is not available to lower the power-on stall speed. There is virtually no difference
between power-on and power-off stall speed. It is not possible in a jet airplane to jam the thrust levers
forward to avoid a stall.
⦁ Jet engine response at low rpm is slower. This characteristic requires that the approach be flown at a stable
speed and power setting on final so that sufficient power is available quickly if needed.
⦁ Jet airplanes are consistently heavier and have faster approach speeds than a comparably sized propeller
airplane. Since greater force is required to overcome momentum for speed changes or course corrections,
the typical jet responds less quickly than the propeller airplane and requires careful planning and stable
conditions throughout the approach.
⦁ When the speed does increase or decrease, there is little tendency for the jet airplane to re-acquire the
original speed. The pilot needs to make speed adjustments promptly in order to remain on speed.
⦁ Drag increases faster than lift and produces a high sink rate at low speeds. Jet airplane wings typically have
a large increase in drag in the approach configuration. When a sink rate does develop, the only immediate
remedy is to increase pitch attitude (AOA). Because drag increases faster than lift, that pitch change rapidly
contributes to an even greater sink rate unless a significant amount of power is promptly applied.
These flying characteristics of jet airplanes make a stabilized approach an absolute necessity.
Stabilized Approach
The performance charts and the limitations contained in the FAA-approved AFM are predicated on momentum values that result from
programmed speeds and weights. Runway length limitations assume an exact 50-foot threshold height at an exact speed of 1.3 times
VSO. That “window” is critical and is a prime reason for the stabilized approach. Performance figures also assume that once through
the target threshold window, the airplane touches down in a target touchdown zone approximately 1,000 feet down the runway, after
which maximum stopping capability is used.
The basic elements to the stabilized approach are listed below as follows:
⦁ The airplane should be in the landing configuration by 1,000 feet AGL in the approach. The landing
gear should be down, landing flaps selected, trim set, and fuel balanced. Ensuring that these tasks
are completed helps keep the number of variables to a minimum during the final approach.
⦁ The airplane should be on profile before descending below 1,000 feet. Configuration, trim, speed, and
glidepath should be at or near the optimum parameters early in the approach to avoid distractions and
conflicts as the airplane nears the threshold window. An optimum glidepath angle of about 3° should be
established and maintained.
⦁ Indicated airspeed should be between zero and 10 knots above the target airspeed by 500 feet AGL. There
are strong relationships between trim, speed, and power in most jet airplanes, and it is important to stabilize
the speed in order to minimize those other variables.
⦁ The optimum descent rate is dependent upon ground speed. A rule of thumb is to multiply half of ground
speed by 10. For example, a 130-knot ground speed should result in a (65 times 10) 650 feet per minute
descent rate. Typical descent rates fall between 500 and 700 feet per minute. An excessive vertical speed
may indicate a problem with the approach.
Every approach should be evaluated at 500 feet. In a typical jet airplane, this is approximately 1 minute from touchdown. If the
approach is not stabilized at that height, a go-around should be initiated. [Figure 16-18]
Figure 16-18. Stabilized approach.
Approach Speed
Any speed deviation on final approach should be detected immediately and corrected. With experience, the pilot is able to detect the
onset of an increasing or decreasing airspeed trend, which normally can be corrected with a small adjustment. It is imperative the pilot
does not allow the airspeed to decrease below V REF or a high sink rate can develop. If an increasing sink rate is detected, it should be
countered by increasing the AOA and simultaneously increasing thrust to counter the extra drag. The degree of correction depends on
how much the sink rate needs to be reduced. For small amounts, smooth and gentle, almost anticipatory corrections are sufficient. For
large sink rates, drastic corrective measures would be required that, even if successful, would destabilize the approach.
A common error in the performance of approaches in jet airplanes is excess approach speed. Excess approach speed carried thr ough
the threshold window and onto the runway increases the minimum stopping distance required by 20–30 feet per knot for a dry runway
and 40–50 feet for a wet runway. Worse yet, the excess speed increases the chances of an extended flare, which increases the distance
to touchdown by approximately 250 feet for each excess knot in speed.
Proper speed contro l on fin al approach is of primary importance. Th e pilot should anticip ate the need for speed adjustmen t so that
only small adjustments are required, and the airplane arrives at the approach threshold window exactly on speed.
Glidepath Control
The optimum glidepath angle is about 3°. On visual approaches, pilots may have a tendency to make flat approaches. A flat approach,
however, increases landing distance and should be avoided. For example, an approach angle of 2° instead of a recommended 3° adds
500 feet to landing distance.
A more common error is excessive height over the threshold. This could be the result of an unstable approach or a stable but high
approach. It also may occur during a nonprecision instrument approach where the missed approach point is close to or at the runway
threshold. Regardless of the cause, excessive height over the threshold most likely results in a touchdown beyond the normal aiming
point. An extra 50 feet of height over the threshold adds approximately 1,000 feet to the landing distance. The airplane should arrive
at the approach threshold window exactly on altitude (50 feet above the runway).
The Flare
The flare reduces the approach rate of descent to a more acceptable rate for touchdown. Unlike light airplanes, a jet airplane should
be flown onto the runway rather than “held off” the surface as speed dissipates. A jet airplane is aerodynamically clean even in the
landing configuration, and its engines still produce residual thrust at idle rpm. Holding it off during the flare in an attempt to make a
smooth landing greatly increases landing distance. A firm landing is normal and desirable. A firm landing does not mean a har d
landing, but rather a deliberate or positive landing.
For most airports, the airplane passes over the end of the runway with the landing gear 30 –45 feet above the surface, depending on
the landing flap setting and the location of the touchdown zone. It takes 5 –7 seconds from the time the airplane passes the end of the
runway until touchdown. The flare is initiated by increasing the pitch attitude just enough to reduce the sink rate to 100 –200 fpm
when the landing gear is approximately 15 feet above the runway surface. In most jet airplanes, this requires a pitch attitude increase
of only 1° to 3°. The thrust is smoothly reduced to idle as the flare progresses.
The normal speed bleed off during the time between passing the end of the runway and touchdown is just a few knots. Most of the
decrease occurs during the flare when thrust is reduced. If the flare is extended (held off) while an additional speed is bled off,
hundreds or even thousands of feet of runway may be used up. [Figure 16-19] The extended flare also results in additional pitch
attitude, which may lead to a tail strike. It is, therefore, essential to fly the airplane onto the runway at the target touchdown point,
even if the speed is excessive. A deliberate touchdown should be planned and practiced on every flight. A positive touchdown helps
prevent an extended flare.
Figure 16-19. Extended flare.
Pilots should learn the flare characteristics of each model of airplane they fly. The visual reference cues observed from each airplane
are different because window geometry and visibility are different. The geometric relationship between the pilot’s eye and the landing
gear is different for each make and model. It is essential that the flare maneuver be initiated at the proper height —not too high and
not too low.
Beginning the flare too high or reducing the thrust too early may result in the airplane floating beyond the target touchdown point or
may include a rapid pitch up as the pilot attempts to prevent a high sink rate touchdown. This can lead to a tail strike. The flare that is
initiated too late may result in a hard touchdown.
Proper thrust management through the flare is also important. In many jet airplanes, the engines produce a noticeable effect on pitch
trim when the thrust setting is changed. A rapid change in the thrust setting requires a quick elevator response. If the thrust levers are
moved to idle too quickly during the flare, the pilot may need to make rapid changes in pitch control. If the thrust levers are moved
more slowly, the elevator input can be more easily coordinated.
Touchdown and Rollout
A proper approach and flare positions the airplane to touch down in the touchdown target zone, which is usually about 1,000 feet
beyond the runway threshold. Once the main wheels have contacted the runway, the pilot should maintain directional control an d
initiate the stopping process on the runway that remains in front of the airplane. The runway distance available to stop is longest if the
touchdown was on target. The energy to be dissipated is least if there is no excess speed.
At the point of touchdown, the airplane represents a very large mass that is moving at a relatively high speed. The large total energy
gets dissipated by the brakes, the aerodynamic drag, and the thrust reversers (if available). The nose-wheel should be lowered onto
the ground immediately after touchdown because a jet airplane decelerates poorly when held in a nose-high attitude, and placing the
nose-wheel tire(s) on the ground assists in maintaining directional control. Lowering the nose gear decreases the wing AOA,
decreasing the lift, placing more load onto the tires, thereby increasing tire- to-ground friction. Landing distance charts for jet
airplanes assume that the nose-wheel is lowered onto the runway within 4 seconds of touchdown.
There are only three forces available for stopping the airplane: wheel braking, reverse thrust, and aerodynamic braking. Of the three,
the brakes are most effective and therefore the most important stopping force for most landings. When the runway is very slippery,
reverse thrust and drag may be the dominant forces. Both reverse thrust and aerodynamic drag are most effective at high spee ds.
Neither is affected by runway surface conditions. Brakes, on the other hand, are most effective at low speed. The landing rollout
distance depends on the touchdown speed, what forces are applied, and when they are applied. The pilot controls the what and when
factors, but the maximum braking force may be limited by tire-to-ground friction.
The pilot should begin braking as soon after touchdown and wheel spin-up as possible, and smoothly continue the braking until
stopped or a safe taxi speed is reached. However, caution should be used if the airplane is not equipped with a functioning anti-skid
system. In such a case, heavy braking can cause the wheels to lock and the tires to skid.
Both directional control and braking utilize tire ground friction. They share the maximum friction force the tires can provide.
Increasing either subtracts from the other. Understanding tire ground friction, how runway contamination affects it, and how to use
the friction available to maximum advantage is important to a jet pilot.
Spoilers should be deployed immediately after touchdown because they are most effective at high speed. Timely deployment of
spoilers increases drag significantly, but more importantly, they spoil much of the lift the wing is creating, thereby causing more of
the weight of the airplane to be loaded onto the wheels. The spoilers increase wheel loading, which increases the tire ground friction
force making the maximum tire braking forces available.
Like spoilers, thrust reversers are most effective at high speeds and should be deployed quickly after touchdown. However, the pilot
should not command significant reverse thrust until the nose-wheel is on the ground. If the reversers deploy asymmetrically resulting
in an uncontrollable yaw toward the side with more reverse thrust, the pilot needs whatever nose-wheel steering is available to
maintain directional control. When runway length is not a factor, using idle reverse thrust may be adequate.
Jet Airplane Systems and Maintenance
All FAA-certificated jet airplanes are certificated under Title 14 of the Code of Federal Regulations (14 CFR) part 25, which contains
the airworthiness standards for transport category airplanes. The FAA-certificated jet airplane is a highly sophisticated machine with
proven levels of performance and guaranteed safety margins. The jet airplane’s performance and safety margins can only be realized,
however, if the airplane is operated in strict compliance with the procedures and limitations contained in the FAA-approved AFM for
the particular airplane. Furthermore, in accordance with 14 CFR part 91, section 91.213(a), a turbine-powered airplane does not
qualify to takeoff with inoperable instruments or equipment installed unless, among other requirements, an approved Minimum
Equipment List (MEL) exists for that aircraft, and the aircraft is operated under all applicable conditions and limitations contained in
the MEL (section 91.213(a)(5)).
Minimum Equipment List
The ME L serv es as a referen ce guid e fo r dispatcher s an d pilo ts to determin e wheth er takeof f o f an aircraf t w ith inoperative
instruments or equipment is authorized under the provisions of applicable regulatory requirements.
The operator models the MEL after the FAA’s Master MEL (MMEL) for each type of aircraft and the Administrator approves the
MEL before its implementation. The MEL includes a “General” section, comprised of definitions, general policies, as well as
operational procedures for flight crews and maintenance personnel. Each aircraft component addressed in the MEL is listed in an
alphabetical index for quick reference. A table of contents further divides the manual in different chapters, each numbered for its
corresponding aircraft system designation (i.e., the electrical system, also designated as system number 24, would be found in chapter
24 of the MEL).
Pilots may defer repair of items on those aircraft systems and components allowed by the approved MEL. Per 14 CFR part 91,
section 91.213(a)(3)(ii), an MEL must provide for the operation of the aircraft with the instruments and equipment in an inoperable
condition. If particular items do not allow for safe operation, they do not appear on the MEL and takeoff is not authorized until
the item is adequately repaired or replaced (section 91.213(a)). In cases where repairs may temporarily be deferred, operation or
dispatch of an aircraft whose systems have been impaired is often subject to limitations or other conditional requirements
explicitly stated in the MEL. Such conditional requirements may be of an operational nature, a mechanical nature, or both.
Mechanical conditions outlined in the MEL may require precautionary pre-flight checks, partial repairs prior to departure, or the
isolation of selected elements of the deficient aircraft system (or related interacting systems), as well as the securing of other system
components to avoid further degradation in flight. The MEL may contain either a step-by-step description of required
partial maintenance actions or a list of numerical references to the Maintenance Procedures Manual (MPM) where each corrective
procedure is explained in detail. Procedures performed to ensure the aircraft can be safely operated are categorized as either
pperations procedures or maintenance procedures. The MEL will denote which by indicating an “O” or an “M” as appropriate.
If operational and mechanical conditions can be met, an authorized person makes an entry in the aircraft MEL Deferral Record and
issues a temporary placard. This authorizes the operation for a limited time before permanent repairs take place. The placard is
affixed by maintenance personnel or the flight crew onto or next to the instrument or control mechanism to remind the flight crew of
any limitations.
The MEL only applies while the aircraft sits on the ground awaiting departure or takeoff. It is essentially a dispatching reference tool
used in support of all applicable Federal Aviation Regulations. If dispatchers are not required by the operator’s certificate , flight
crews still need to refer to the MEL before dispatching themselves to ensure that the flight is planned and conducted within
the operating limits set forth in the MEL. Once the aircraft leaves the ground, any mechanical failures should be addressed using
the appropriate checklists and approved AFM, not the MEL. Although a pilot may refer to the MEL for background information
and documentation, actions in flight should be based strictly on instructions provided by the AFM (i.e., Abnormal or
Emergency sections).
Configuration Deviation List
A Configuration Deviation List (CDL) is used in the same manner as an MEL but it differs in that it addresses missing external parts
of the aircraft rather than failing internal systems and their constituent parts. They typically include elements, such as service doors,
power receptacle doors, slat track doors, landing gear doors, APU ram air doors, flaps fairings, nose-wheel spray deflectors, position
light lens covers, slat segment seals, static dischargers, etc.
Chapter Summary
Some of the differences when transitioning from props to jets include:
⦁ Engine intake suction and exhaust create a ground hazard.
⦁ There is no propeller-induced lift when power increases.
⦁ Engine spool up time from low power settings is longer.
⦁ Swept wing stalls begin at the tips.
⦁ Higher speeds require smaller and smoother flight control inputs.
⦁ Descents require more planning and optimally occur at idle power.
⦁ When descending at speeds above L/DMAX, increasing speed increases rate of descent and descent angle.
There are many considerations for a pilot when transitioning to turbojet-powered airplanes. In addition to the information found in
this chapter and type specific information that will be found in an FAA-approved Airplane Flight Manual, a pilot can find basic
aerodynamic information for swept wing jets, considerations for operating at high altitudes, and airplane upset causes and general
recovery procedures in the Airplane Upset Recovery Training Aid, Supplement, pages 1-14, and all of Section 2 found at
www.faa.gov/other_visit/aviation_industry/airline_operators/training/media/ap_upsetrecovery_book.pdf.