Definition
The highest airspeed an airplane can sustain in straight-and-level flight at a given altitude and weight, with the engine producing maximum available thrust or power. At this speed, all available thrust is being used to overcome drag, leaving no surplus power to accelerate or climb.
Plain English
The fastest the airplane can go while staying level, with the engine pushed to its full output for that altitude. Go any faster and it would have to descend; go slower and there is power left over to climb.
Context Anchor
Seen in airplane control and energy-management discussions, especially when explaining how elevator and power affect altitude, speed, and the airplane’s energy state.
Derivation
Maximum comes from a Latin word meaning “greatest.” Level, in this aviation use, means holding the same altitude. Together, the phrase means the greatest airspeed available while staying at the same altitude, not the greatest speed the airplane could reach in a dive.
Why Pilots Care
Recognizing this speed helps pilots understand performance limits and decide whether to use pitch primarily for airspeed or altitude control.
Intuition Check
Do not read “level” as just wings-level, and do not read “maximum” as the never-exceed speed. Here it means the greatest airspeed the airplane can maintain while holding a constant altitude in the stated condition.
Example Sentence 1
At cruise altitude, the airplane settled at its maximum level flight airspeed with the throttle fully forward and showed no further acceleration.
Example Sentence 2
Attempting to fly faster than maximum level flight airspeed in level flight requires more power than the engine can deliver, so the nose must be lowered.