Mach tuck description?

• A. Nose-up pitch due to high speed.
• B. Engine flameout.
• C. Center of pressure moves aft; elevator becomes aerodynamically useless due to separated airflow; shockwave can cause drag.
• D. Wingtip stall.

Answer: (C)

Mach tuck happens when an aircraft pushes into high-subsonic speeds where compressibility effects cause shock waves to form and shift the center of pressure aft along the wing. That rearward shift creates a nose-down pitching moment, which the pilot must counteract. At the same time, the airflow over the horizontal stabilizer can become separated or disrupted by the shock-induced pressure changes, making the elevator much less effective. The shock wave itself can also add drag, compounding the control difficulty. This combination—center of pressure moving aft, reduced elevator authority due to separated airflow, and drag from the shock—best describes Mach tuck. Other descriptions like nose-up pitch at high speed or wingtip stalls refer to different phenomena and don’t capture the same flight-control challenges.