FAA Flight Instructor Airplane (FIA)Performance, Weight and BalanceHard
During a short-field takeoff, a pilot notices the airplane becomes airborne prior to reaching the recommended takeoff safety speed while still within ground effect. This situation is most hazardous because:
- AGround effect increases the stall speed, making the airplane more prone to an accelerated stall
- BThe reduced induced drag experienced in ground effect will permanently improve climb performance once clear of the effect
- CThe increased induced drag near the surface requires a nose-down attitude to accelerate safely
- DThe airplane may be unable to climb out of ground effect, or it may settle back to the runway as it climbs above the effect
Show answer & explanationAnswer & explanation
Correct answer: D. The airplane may be unable to climb out of ground effect, or it may settle back to the runway as it climbs above the effect
Ground effect reduces induced drag and can allow the airplane to become airborne at a lower speed than normally required. As the airplane climbs out of ground effect, induced drag increases sharply; if the airplane has not yet reached climb speed, it may be unable to climb further or may even settle back onto the runway.
Why the other options are wrong
- A. Ground effect reduces induced drag and effectively lowers stall speed slightly, not increases it.
- B. Induced drag increases, not decreases, once clear of ground effect, so this misstates the physics.
- C. Ground effect reduces induced drag, so less nose-down correction is needed, not more.
Ground Effect Hazard
Ground effect reduces induced drag near the surface, which can let an airplane become airborne below climb speed and then be unable to climb, or settle back, once it leaves the effect.
- Ground effect occurs within about one wingspan of the surface
- Induced drag is significantly reduced in ground effect
- Premature liftoff in ground effect can cause a hazardous inability to climb
Memory trick: Ground effect gives a false sense of flying free