In Class B airspace, what must all aircraft obtain to operate within its boundaries?

In Class B airspace, all aircraft must obtain ATC clearance to operate within its boundaries. This requirement is fundamental to maintaining the safety and efficiency of air traffic in areas where many aircraft, including commercial airliners, are operating simultaneously. The ATC clearance serves as an authorization that provides specific instructions to pilots, including altitude, routing, and any other pertinent information necessary for safe navigation through this busy airspace.

The Class B airway is typically located around major airports where high-density traffic exists, and the requirement for ATC clearance helps prevent collisions and ensures that all aircraft are following a coordinated traffic flow. This regulatory measure is designed to enhance safety and is essential for pilots to adhere to before entering this controlled airspace.