You are at 12,000 ft and told to descend to 8,000 ft while maintaining 300 kts. Do you still have to stay at 300 kts?

• A. Yes, you must maintain 300 kts until you reach 8,000 ft.
• B. No; you should be at or below 250 kts before 10,000 ft.
• C. Yes; you must maintain 300 kts until you reach 8,000 ft.
• D. No; you may accelerate to 320 kts.

Answer: (B)

Speed must be limited below 10,000 feet. In the United States, you’re not allowed to exceed 250 knots indicated airspeed anywhere below 10,000 ft MSL. So while descending from 12,000 ft toward 8,000 ft, you must slow to 250 knots or less before you cross 10,000 ft. Once you’re below that altitude, you may stay at or below 250 knots, and you could potentially accelerate later if cleared by ATC. That’s why you shouldn’t maintain 300 knots through the descent; you should be at or below 250 knots before reaching 10,000 ft.