Altitude band for 250-300 KCAS is which of the following?

• A. 0-8000' MSL
• B. 28000-40000' MSL
• C. 0-28,000' MSL
• D. 8,000-28,000' MSL

Answer: (D)

Altitude bands are the certified ranges where a given airspeed is approved within the airplane’s operating envelope. For this speed range, 250 to 300 KCAS, the aircraft is limited to mid-altitude operation to keep margins for structural loads, engine performance, and cooling within tested limits.

At lower altitudes, the air is denser, which increases dynamic pressure and the stress on the airframe at high subsonic speeds. That can push you toward or beyond certification limits. At higher altitudes, the air is thinner, which can reduce engine performance and cooling margins and tighten maneuvering safety margins, even if the indicated speed is the same. The 8,000 to 28,000 feet MSL window provides a balance where the aircraft can sustain 250–300 KCAS with adequate structural safety and system performance.

So the altitude band for this speed range is 8,000 to 28,000 feet MSL. The other ranges would place the operation outside the tested envelope for this speed, either too dense or too thin in the air, compromising safety margins.