FAA Airline Transport Pilot (ATM)Transport Aerodynamics and High-Altitude OperationsMedium
An aircraft is decelerating on final approach and slows below its minimum drag speed (L/D max). To maintain a constant airspeed and glide path, the pilot must add power as speed decreases further. This region of flight, where additional thrust is required to maintain slower airspeeds, is known as:
- AThe region of normal command
- BCoffin corner
- CThe absolute ceiling
- DThe area of reversed command
Show answer & explanationAnswer & explanation
Correct answer: D. The area of reversed command
Below L/D max (minimum drag speed), the total drag increases as speed decreases, requiring more thrust to maintain airspeed — the opposite of normal (front side) flight. This backside-of-the-power-curve regime is called the region (or area) of reversed command.
Why the other options are wrong
- A. Region of normal command is above L/D max, where less power is needed as speed decreases.
- B. Coffin corner concerns high-altitude buffet margins, not low-speed approach handling.
- C. Absolute ceiling refers to maximum altitude capability, unrelated to the power curve's slow-speed side.
Region of Reversed Command
The slow-speed flight regime (below L/D max) where additional thrust is required to maintain slower airspeed because total drag increases as speed decreases.
- Also called the 'back side of the power curve'
- Occurs at speeds below minimum drag (L/D max) speed
- Requires pitch for airspeed and power for altitude control technique
Memory trick: Backside of the curve: slower needs MORE gas, not less