FAA Commercial Pilot Airplane (CAX)Aerodynamics and PerformanceMedium
An airplane's maneuvering speed (Va) is 120 KIAS at its maximum gross weight of 3,000 pounds. If the airplane is now flown at a weight of 2,400 pounds, what is the approximate new maneuvering speed?
- A116 KIAS
- B96 KIAS
- C107 KIAS
- D134 KIAS
Show answer & explanationAnswer & explanation
Correct answer: C. 107 KIAS
Va varies with the square root of the weight ratio: Va2 = Va1 × √(W2/W1) = 120 × √(2,400/3,000) = 120 × √0.8 = 120 × 0.894 ≈ 107 KIAS. As weight decreases, maneuvering speed also decreases.
Why the other options are wrong
- A. This value is too high and does not reflect the proper weight adjustment.
- B. This value results from an incorrect proportional (non-square-root) calculation.
- D. This assumes Va increases with lighter weight, which is incorrect.
Maneuvering Speed vs. Weight
Va decreases as aircraft weight decreases because a lighter airplane stalls at a lower speed, requiring less speed to reach critical AOA under load.
- Formula: Va2 = Va1 × √(W2/W1)
- Va decreases with decreasing weight
- Va listed in POH is for max gross weight
- Flying above adjusted Va at light weight risks structural damage during turbulence
Memory trick: Lighter plane, lighter Va — weight and speed shrink together!