What is the speed limit at 10,000 feet and above?

At altitudes of 10,000 feet and above, the speed limit for aircraft is determined by the regulations set forth by aviation authorities, such as the FAA in the United States. While the maximum permissible speed varies depending on the specific aircraft category and operational circumstances, a general rule is that the speed limit is set at Mach 1, which corresponds to the speed of sound.

When aircraft exceed Mach 1, they are transitioning into supersonic flight, which can impose additional engineering and regulatory considerations. Most commercial aircraft are designed to operate efficiently below this threshold, but in certain circumstances, such as in special flight operations, they may be allowed to exceed Mach 1.

The other choices, while applicable in different contexts or at variances in altitude, do not set the speed limit at 10,000 feet or above as effectively as Mach 1 does for supersonic-capable aircraft. As such, understanding the context and regulations surrounding high-altitude operations helps clarify why Mach 1 is the appropriate speed limit in this scenario.