← All explained questions · Aerodynamics and Principles of Flight
In steady, straight-and-level, unaccelerated flight, which relationship between the forces is true?
Choices
✓ Lift equals weight and thrust equals dragcorrect
In equilibrium the opposing forces are equal, so altitude and airspeed stay constant.
Lift is greater than weight and thrust is greater than drag
That would produce a climbing, accelerating airplane, not level flight.
Thrust is greater than drag and lift is less than weight
That is not the equilibrium condition for level flight.
All four forces are zero
The forces exist and are balanced, not absent.
Why
In unaccelerated straight-and-level flight the four forces are in equilibrium: lift equals weight and thrust equals drag.
FAA source: PHAK Ch. 5browse the reference library →
Original study question written for this course — representative of FAA knowledge-test topics, not an actual current FAA exam question.