Airliners are designed to cruise at which Mach range before Mach tuck occurs if exceeded?

• A. 0.5 to 0.6
• B. 0.7 to 0.9
• C. 1.0 to 1.2
• D. 0.3 to 0.4

Answer: (B)

Mach tuck is the nose-down pitching tendency that appears as speed enters the transonic regime and shock effects on the wing alter the lift distribution and control effectiveness. Airliners are designed to operate in the high-subsonic to low-transonic range where drag is manageable and the elevator and stability margins remain adequate. That practical cruise envelope is typically around Mach 0.7 to 0.9, with many jets flying near Mach 0.78–0.85. If you push beyond this band, transonic effects intensify and the pitching moment can shift nose-down, making Mach tuck more likely unless countered. So the range where cruise is sustained before Mach tuck becomes a concern is about 0.7 to 0.9 Mach.