Definition
An air traffic control instruction requiring a pilot to be at a specified altitude when the aircraft passes over a named navigation fix. The pilot must plan the climb or descent so that the aircraft reaches the assigned altitude no later than crossing the fix.
Plain English
ATC is telling you: 'By the time you fly over this point, be at this altitude.' You manage your climb or descent to make that happen.
Context Anchor
Often heard in instrument flying, arrival procedures, approach clearances, and air traffic control instructions.
Why Pilots Care
Ensures vertical separation from terrain, obstacles, and other traffic while complying with the published or cleared flight path.
Intuition Check
Do not read “cross” as simply flying across a line or runway. Here it means reaching and passing a named navigation point while already at the assigned altitude.
Example Sentence 1
ATC instructed the crew to cross BOXER at altitude 10,000 feet, so the captain began the descent early to avoid arriving high.
Example Sentence 2
The approach chart requires crossing the fix at altitude before beginning the final descent.