Which entity has the authority to amend an ATC clearance?

Air Traffic Control (ATC) has the authority to amend an ATC clearance. This is a crucial responsibility because ATC is tasked with ensuring the safe and efficient movement of air traffic. They provide instructions to pilots regarding their flight paths, including departures, arrivals, and in-flight adjustments based on current traffic conditions, weather, and other operational considerations.

When a pilot receives a clearance, it is based on specific flight parameters, and if changes need to be made during flight operations—such as rerouting due to weather or traffic congestion—only ATC has the jurisdiction to issue a new or amended clearance. This authority is fundamental to maintaining safety and order in the airspace system, allowing for real-time management of aircraft movements.

In contrast, while the pilot in command must follow ATC's instructions, they cannot unilaterally change a clearance without ATC's input. Ground control personnel primarily focus on aircraft on the ground and might facilitate movement and clearances related to taxiing but do not have authority to amend airborne clearances. The aircraft manufacturer does not play a role in flight operations or clearances, as their responsibility pertains to the design and integrity of the aircraft itself.