Definition
An air traffic control technique in which a controller issues radar vectors that take an aircraft across the final approach course (rather than directly onto it) in order to create the required spacing between that aircraft and other traffic on the approach. The aircraft is then turned back and re-vectored to intercept the final approach course once adequate separation exists.
Plain English
Instead of turning you straight onto the final approach, the controller sends you across it for a short distance to create more room between you and the aircraft ahead, then turns you back to line up with the runway.
Context Anchor
Used during instrument approaches when a controller is giving radar headings to place the aircraft on the final approach course.
Derivation
A 'vector' in ATC use is a magnetic heading assigned by the controller. 'Across final' means the heading takes the aircraft through and past the final approach course. 'For spacing' states the reason: to build separation between aircraft.
Why Pilots Care
Correct spacing avoids wake turbulence and prevents unnecessary go-arounds caused by insufficient separation on final.
Grounding Statement
Picture the aircraft crossing through the approach path, continuing straight for a short time, then receiving another heading to come back and join the approach with more room from other traffic.
Intuition Check
“Across final” does not mean you are abandoning the approach. It means you are being taken through the final approach course temporarily, usually to create more room between aircraft.
Example Sentence 1
ATC advised, 'Expect vectors across final for spacing,' so the crew continued on the assigned heading through the localizer rather than turning to intercept.
Example Sentence 2
After receiving vectors across final for spacing, the pilot was turned to intercept once the required interval was established.