Figure 16-9. Unmodified swept wing stall characteristics.
Some T-tail configurations are prone to so-called deep stalls where the tail can become immersed in the wing wake at very high
angles of attack and lose effectiveness. Such a situation can be accompanied by a high-rate of descent. Since high angles of attack can
occur at any pitch attitude, even a pitch attitude with the nose below the horizon, it may seem counterintuitive in such a situation to
take the appropriate recovery action, which is to push the nose down even further.
Deep stalls may be unrecoverable. Fortunately, they are easily avoided as long as published limitations are observed. On thos e
airplanes susceptible to deep stalls (not all swept or tapered wing airplanes are), sophisticated stall warning systems such as stick
shakers are standard equipment. A stick pusher (if installed), as its name implies, acts to automatically reduce the airplane ’s AOA
before the airplane reaches a dangerous stall condition, or it may aid in recovering the airplane from a stall if an airplane ’s natural
aerodynamic characteristics do so weakly. Pilots should avoid situations that would activate a stick pusher when close to the ground.
Pilots undergoing training in jet airplanes are taught to recover at the first indication of an impending stall instead of going beyond
those initial cues and into a full stall. Normally, this is indicated by aural stall warning devices, annunciators, or activation of the
airplane’s stick shaker. Stick shakers normally activate around 107 percent of the actual stall speed. In response to a stall warning, the
proper action is for the pilot to apply a nose-down input until the stall warning stops (pitch trim may be necessary). Then, the wings
are rolled level, followed by adjusting thrust to return to normal flight. The elapsed time will be small between these actions,
particularly at low altitude where significant available thrust exists. It is important to understand that reducing AOA eliminates the
stall, but added thrust will allow the descent to be stopped once the wing is flying again. Note that airplanes without vortex generators
may stall with little to no buffet.
At high altitudes the stall recovery technique is the same. A pilot will need to reduce the AOA by lowering the nose until the stall
warning stops. However, after the AOA has been reduced to where the wing is again developing efficient lift, the airplane will still
likely need to accelerate to a desired airspeed. At high altitudes where the available thrust is significantly less than at lower altitudes,
recovery may require significant pitch down to regain airspeed. As such, several thousand feet or more of altitude loss may occur
during the recovery. The above discussion covers most airplanes; however, the stall recovery procedures for a particular make and
model airplane may differ, as recommended by the manufacturer, and are contained in the FAA-approved Airplane Flight Manual for
that airplane.
Drag Devices
Jet airplanes have higher glide ratios than piston-powered airplanes. Due to their low drag design, jets take more time and distance to
descend or reduce speed. Therefore, jet airplanes are often equipped with drag devices, such as spoilers and speed brakes.
The primary purpose of spoilers is to spoil lift. The most common type of spoiler consists of one or more rectangular plates that lie
flush with the upper surface of each wing. They are installed approximately parallel to the lateral axis of the airplane and are hinged
along the leading edges. When deployed, spoilers deflect up against the relative wind, which interferes with the flow of air about the
wing. [Figure 16-10] This both spoils lift and increases drag. Spoilers are usually installed forward of the flaps but not in front of the
ailerons so as not to interfere with roll control. Some aircraft use spoilers to augment roll control.
Figure 16-10. Spoilers.
When flight and ground spoilers are deployed after landing, most of the wing’s lift is destroyed. This action transfers the airplane’s
weight to the landing gear so that the wheel brakes are more effective. A secondary beneficial effect of deploying spoilers on landing
is that they create considerable drag, adding to the overall aerodynamic braking.
The primary purpose of speed brakes is to produce drag. Spoilers may also serve as speed brakes, or they may be panels attached to
the fuselage. Deploying speed brakes results in a rapid decrease in airspeed and/or an increased rate of descent. Typically, speed
brakes can be deployed at any time during flight. There is usually a certain amount of noise and buffeting associated with the use of
speed brakes, along with an obvious penalty in fuel consumption. Pilots can minimize the use of speed brakes with proper descent and
approach planning. Procedures for the use of spoilers and/or speed brakes in various situations are contained in the FAA-approved
AFM for the particular airplane.
Thrust Reversers
Jet airplanes have high kinetic energy during the landing roll because of weight and speed. This energy is difficult to dissipate
because a jet airplane has low drag with the nose-wheel on the ground, and the engines continue to produce forward thrust with the
power levers at idle. While wheel brakes serve as the primary means to stop the airplane, reverse thrust, when available, assists in
deceleration.
Certain thrust reverser designs effectively reverse the flow of the exhaust gases. The flow does not completely reverse. Typically, the
final path of the exhaust gases is about 45° from straight ahead. This, together with the losses from the flow paths, reduces reverse
thrust efficiency. If the pilot uses less than maximum rpm in reverse, the reverse thrust is further reduced.
Normally, a jet engine has one of two types of thrust reversers: a target reverser or a cascade reverser. [Figure 16-11] Target
reversers are simple clamshell doors that swivel from the stowed position at the engine tailpipe to redirect thrust to a more forward
direction.
Figure 16-11. Thrust reversers.
Cascade reversers are normally found on turbofan engines and are often designed to reverse only the fan air portion. Blocking doors
in the shroud obstruct forward fan thrust and redirect it through cascade vanes to generate reverse thrust.
On most installations, the pilot selects reverse thrust with the thrust levers at idle by pulling up the reverse levers to a detent. Doing so
positions the reversing mechanisms for operation but leaves the engines at idle rpm. Further upward and backward movement of the
reverse levers increases engine power. Reverse is canceled by closing the reverse levers to the idle reverse position, then dropping
them fully back to the forward idle position. This last movement selects the stowed position, and the reversers return to the forward
thrust position.
Reverse thrust is more effective at high speed than at low speed. For maximum reverse thrust efficiency, the pilot should use it as
soon as is prudent after touchdown. The pilot should remember that some airplanes tend to pitch nose-up when reverse is selected on
landing and this effect, particularly when combined with the nose-up pitch effect from the spoilers, can cause the airplane to leave the
ground again momentarily. On these types, the airplane should be firmly on the ground with the nose-wheel down before reverse is
selected. Other types of airplanes have no change in pitch, and reverse idle may be selected after the main gear is down and before the
nose-wheel is down. Since reverse thrust may affect directional control, runway surface conditions (e.g., contamination), factor into
the use of reverse thrust. Specific procedures for reverse thrust operation for a particular airplane/engine combination are contained in
the FAA-approved AFM for that airplane.
There is a significant difference between reverse pitch on a propeller and reverse thrust from a jet engine. Idle reverse on a propeller
produces a large amount of drag. On a jet engine, however, selecting idle reverse produces very little reverse thrust. In a jet airplane,
the pilot should select reverse, apply reverse thrust as appropriate, and remain within any AFM limitations.
It is essential that pilots understand not only the normal procedures and limitations of thrust reverser use, but also the procedures for
coping with uncommanded reverse. While thrust reverser systems are designed to prevent unintentional deployment, an
uncommanded or inadvertent deployment of thrust reversers, while airborne, is an emergency. The systems normally contain several
lock systems: one to keep reversers from operating in the air, another to prevent operation with the thrust levers out of the idle detent,
and/or an “auto-stow” circuit to command reverser stowage any time thrust reverser deployment would be inappropriate, such as
during takeoff and while airborne.
Pilot Sensations in Jet Flying
Pilots transitioning into jets may notice these general sensations:
1. response differences
2. increased control sensitivity
3. increased tempo of flight
In some flight conditions, airspeed changes may occur more slowly than in a propeller airplane. At high altitudes, the reduction in
available thrust reduces the ability to accelerate. The long spool-up time required from low throttle settings also may affect
acceleration. Finally, the clean aerodynamic design of a jet can result in more gradual deceleration when thrust is reduced.
The lack of propeller effects results in less drag at low power settings. Other changes the transitioning pilot should notice include the
lack of effective slipstream over the lifting and control surfaces, and the lack of propeller torque effect.
Even though moving the power levers has less effect at low power settings, the pilot should change power settings smoothly. To slow
the airplane, the transitioning pilot may also need to learn when to use available drag devices appropriately.
Transitioning pilots should learn power setting management for different situations. Power settings for desired performance vary
because of significant changes in airplane weight as fuel is consumed. Therefore, the pilot needs to use a variety of cues to achieve
desired performance. For example, airspeed trend information provides feedback for power required.
Power changes may result in a pitching tendency. These characteristics should be noticed and compensated for.
The jet airplane will differ regarding pitch tendencies with the lowering of flaps, landing gear, and drag devices. With experience, the
jet airplane pilot will learn to anticipate the pitch change required for a particular operation. Most jet airplanes are equipped with a
thumb operated pitch trim button on the control wheel. The usual method of operating the trim button is to apply several small,
intermittent applications of trim in the direction desired rather than holding the trim button for longer periods of time, which can lead
to overcontrolling.
The variation of pitch attitudes flown in a jet airplane also results from high thrust, flight characteristics of the low aspect ratio, and
the swept wing. Flight at higher pitch attitudes requires greater reliance on the flight instruments for airplane control since outside
references may be absent. Proficiency in attitude instrument flying, therefore, is essential to successful transition to jet airplane flying.
Control sensitivity will differ amongst various airplanes. Because of the higher speeds flown, the control surfaces are more effective
and a variation of just a few degrees in pitch attitude in a jet can result in over twice the rate of altitude change that would be
experienced in a slower airplane. The sensitive pitch control in jet airplanes is one of the first flight differences that the pilot may
notice, and the transitioning pilot may have a tendency to overcontrol pitch during initial training flights. Accurate and smooth control
is one of the first techniques the transitioning pilot should master. Rather than gripping the yoke with the hand at high speeds, just
using fingertips will result in smoother control inputs.
The pilot flying a swept wing jet airplane should understand that it is normal to fly at higher angles of attack. Depending on weight,
density altitude, and available thrust, the pitch angle on takeoff may seem high. It is also not unusual to have a noticeable nose-up
pitch on an approach to a landing.
Jet Airplane Takeoff and Climb
The following information is generic in nature and, since most civilian jet airplanes require a minimum flight crew of two pilots,
assumes a two-pilot crew. If any of the following information conflicts with FAA-approved AFM procedures for a particular airplane,
the AFM procedures take precedence. Also, if any of the following procedures differ from the FAA-approved procedures developed
for use by a specific air operator and/or for use in an FAA-approved training center or pilot school curriculum, the FAA-approved
procedures for that operator and/or training center/pilot school take precedence.
V-Speeds
The following are speeds that affect the jet airplane’s takeoff performance. The jet airplane pilot should understand how to use these
speeds when planning for takeoff.
⦁ VS —stalling speed or minimum steady flight speed at which the airplane is controllable.
⦁ V1 —critical engine failure speed or takeoff decision speed. It is the speed at which the pilot is to continue
the takeoff in the event of an engine failure or other serious emergency. At speeds less than V1, it is
considered safer to stop the aircraft within the accelerate-stop distance. It is also the minimum speed in the
takeoff, following a failure of the critical engine at VEF, at which the pilot can continue the takeoff and
achieve the required height above the takeoff surface within the takeoff distance.
⦁ VEF —speed used during certification at which the critical engine is assumed to fail.
⦁ VR —rotation speed, or speed at which the rotation of the airplane is initiated to takeoff attitude. This speed
cannot be less than V1 or less than 1.05 × VMCA (minimum control speed in the air). On a single-engine
takeoff, it also allows for the acceleration to V2 at the 35-foot height at the end of the runway.
⦁ VLOF —lift-off speed, or speed at which the airplane first becomes airborne. This is an engineering term
used when the airplane is certificated to meet certain requirements. The pilot takes this speed into
consideration if the AFM lists it.
⦁ V2 —takeoff safety speed, or a referenced airspeed obtained after lift-off at which the required one-
engine-inoperative climb performance can be achieved.
Takeoff Roll
After confirming the runway and position match expectations, the airplane should be aligned in the center of the runway. When
runway length is limited, the brakes should be held while the thrust levers are brought to a power setting specified in the AFM and the
engines allowed to stabilize. The engine instruments should be checked for proper operation before the brakes are released or the
power increased further. This procedure assures symmetrical thrust during the takeoff roll and aids in prevention of oversho oting the
desired takeoff thrust setting. After brake release, the power levers should be set to the pre-computed takeoff power setting and
takeoff thrust adjustments made prior to reaching 60 knots. The final engine power adjustments are normally made by the pilot not
flying. Retarding a thrust lever would only be necessary in case an engine exceeds any limitation.
Takeoff data, including V 1/VR and V 2 speeds, takeoff power settings, and required field length should be computed prior to each
takeoff. For any make and model without an FMS, the data should be recorded on a takeoff data card. This data is based on ai rplane
weight, runway length available, runway gradient, field temperature, field barometric pressure, wind, icing conditions, and runway
condition. Both pilots should review the takeoff data entered in an FMS or separately compute the takeoff data and cross-check with
the takeoff data card. If takeoff plans change while taxiing, the pilot or crew should recalculate the takeoff data.
Figure 16-12. Sample captain’s briefing.
A captain’s briefing is an essential part of crew resource management (CRM) procedures and should be accomplished prior to
takeoff. [Figure 16-12]