Final Answer:
To separate a standard formation flight, add altitude difference to the appropriate radar separation minima. Option C is the answer.
Step-by-step explanation:
When managing air traffic, it's essential to ensure safe separation between aircraft. In the context of a standard formation flight, the separation criteria involve considering the altitude difference between aircraft. The correct option is (c) "Altitude difference." Air traffic controllers use radar separation minima, which are specific distances or altitudes that aircraft must maintain to prevent collisions or other unsafe situations.
Adding altitude difference to the separation minima is crucial in formation flights, allowing controllers to maintain safe spacing vertically. This practice ensures that each aircraft within the formation has adequate clearance to operate safely without compromising the integrity of the airspace.
Option C is the answer.