In a controlled aerodrome, what must pilots obtain before taxiing, taking off, or landing?

Before taxiing, taking off, or landing at a controlled aerodrome, pilots are required to obtain clearance from the appropriate air traffic control unit. This clearance is a critical component of aviation safety and efficiency, as it ensures that aircraft operate in a coordinated manner, minimizing the risk of collisions on the ground and in the air.

Air traffic control provides real-time instructions regarding the movement of aircraft, and their clearance indicates that the runway or taxiway is safe for use at that moment. Without this clearance, pilots may inadvertently enter a hazardous situation where two aircraft could be on the same path, leading to potential accidents.

The other options, such as weather updates and flight plans, while important aspects of flight preparation, do not replace the necessity of receiving ATC clearance. Weather updates inform pilots of conditions they might encounter but do not authorize movement in the controlled airspace. Permission from fellow pilots is not a formal requirement and lacks the authority necessary for safe operations. Likewise, while filing a flight plan is important for flight management and communication with ATC, it does not grant permission to act on the runway or taxiway. Therefore, obtaining clearance from air traffic control is the fundamental requirement before commencing any of these operations at a controlled aerodrome.