Node A6 · Acronym decoder
ATP
Authority to Proceed
What it actually means
A formal go-ahead to start the next chunk of contracted work, often tied to a milestone or an incremental funding release. Distinct from a contract award: ATP is the customer saying "begin phase two" on an existing vehicle. The same letters also appear as Acceptance Test Procedure in test documentation, so read the context.
Where you'll meet it
Contract management correspondence and program schedules, usually as a milestone marker.