What is the high speed descent speed?

What is the high speed descent speed?

• A. .77 Mach or 320 Knots
• B. .74 Mach or 290 Knots
• C. .70 Mach or 250 Knots
• D. 320 Knots or .70 Mach

Answer: (A)

The speed used for a high-speed descent is a designated target that lets you descend efficiently without exceeding limits. For the CRJ-550, that target is Mach 0.77, which is about 320 knots. Mach and knots are two ways to express the same speed—the Mach value is used at higher altitudes where the speed of sound changes with temperature, while knots (indicated airspeed) are a convenient, consistent reference for the crew. So the official high-speed descent speed is given as either 0.77 Mach or 320 knots, meaning they represent the same descent speed. Choosing a lower Mach (or a lower indicated speed that doesn’t correspond to the same Mach) would mean a slower descent, taking longer and potentially missing altitude constraints. The option pairing 320 knots with a lower Mach (0.70) isn’t a match for the same speed, and the other lower Mach/IAS values describe slower descent targets.

The speed used for a high-speed descent is a designated target that lets you descend efficiently without exceeding limits. For the CRJ-550, that target is Mach 0.77, which is about 320 knots. Mach and knots are two ways to express the same speed—the Mach value is used at higher altitudes where the speed of sound changes with temperature, while knots (indicated airspeed) are a convenient, consistent reference for the crew. So the official high-speed descent speed is given as either 0.77 Mach or 320 knots, meaning they represent the same descent speed.

Choosing a lower Mach (or a lower indicated speed that doesn’t correspond to the same Mach) would mean a slower descent, taking longer and potentially missing altitude constraints. The option pairing 320 knots with a lower Mach (0.70) isn’t a match for the same speed, and the other lower Mach/IAS values describe slower descent targets.