What is the maximum indicated airspeed below 10,000 feet MSL?

The maximum indicated airspeed below 10,000 feet MSL is 250 knots. This regulation is in place primarily for safety reasons as it helps to reduce the risk of midair collisions in busy airspace and also minimizes the noise impact on the ground as aircraft are operating at lower altitudes.

This restriction is enforced under Federal Aviation Regulations (FAR) Part 91.117, which specifies that no person may operate an aircraft below 10,000 feet MSL at a true airspeed exceeding 250 knots unless otherwise authorized by air traffic control or in special circumstances. The limit helps maintain a more uniform speed among aircraft in lower airspace, contributing to safer flight operations, especially near airports where many aircraft are taking off and landing.

The other options exceed this regulation and are not applicable below 10,000 feet MSL. Therefore, the correct answer reflects the regulatory requirement designed to enhance air safety and manage aircraft operations effectively in congested airspace.