Chapter 15-Transition to Jet Powered Airplanes

Table of Contents
Jet Engine Basics
Operating the Jet Engine
Jet Engine Ignition
Continuous Ignition
Fuel Heaters
Setting Power
Thrust to Thrust Lever Relationship
Variation of Thrust with RPM
Slow Acceleration of the Jet Engine
Jet Engine Efficiency
Absence of Propeller Effect
Absence of Propeller Slipstream
Absence of Propeller Drag
Speed Margins
Recovery from Overspeed Conditions
Mach Buffet Boundaries
Low Speed Flight
Drag Devices
Thrust Reversers
Pilot Sensations in Jet Flying
Jet Airplane Takeoff and Climb
Pre-Takeoff Procedures
Takeoff Roll
Rotation and Lift-Off
Initial Climb
Jet Airplane Approach and Landing
Landing Requirements
Landing Speeds
Significant Differences
The Stabilized Approach
Approach Speed
Glidepath Control
The Flare
Touchdown and Rollout


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 ôheld offö 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 r.p.m. Holding it off during the flare in a attempt to make a smooth landing will greatly increase landing distance. A firm landing is normal and desirable. A firm landing does not mean a hard landing, but rather a deliberate or positive landing.

For most airports, the airplane will pass over the end of the runway with the landing gear 30 û 45 feet above the surface, depending on the landing flap setting and the location of the touchdown zone. It will take 5 û 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 û 200 feet per minute when the landing gear is approximately 15 feet above the runway surface. In most jet airplanes, this will require a pitch attitude increase of only 1 to 3 . The thrust is smoothly reduced to idle as the flare progresses.

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The normal speed bleed off during the time between passing the end of the runway and touchdown is 5 knots. Most of the decrease occurs during the flare from each cockpit are different because window geometry and visibility are different. The geometric relationship between the pilotÆs eye and the landing gear will be different for each make and model. It is essential that the flare maneuver be initiated at the proper heightùnot 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

Figure 15-25. Extended flare.

Figure 15-25. Extended flare.

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