Plain English Meaning
Fly this heading until you cross the next part of the procedure, then turn onto it.
Full Definition
A path terminator leg in an RNAV procedure that instructs the aircraft to fly a specified magnetic heading until it intercepts the next leg of the procedure. The leg has no defined endpoint of its own; it terminates only when the aircraft crosses the course of the following leg.
Context Anchor
Seen in instrument procedure coding and on GPS or flight-management-system displays for departures, arrivals, and missed approaches.
Derivation
In ARINC 424 path terminator coding, each leg type is named by two letters: the first letter is the path being flown, the second is what ends the leg. 'V' stands for a heading (vector) and 'I' stands for an intercept. So 'VI' literally reads as 'heading-to-intercept.'
Why Pilots Care
Ensures the aircraft joins the intended track at the correct angle without overshooting or requiring last-minute corrections.
Intuition Check
Do not read “heading” as the exact path over the ground; wind can push the aircraft sideways while it holds that heading. “Intercept” means joining the specified course, not just crossing near it.
Example Sentence 1
After takeoff, the SID coded a VI leg of 090, so we held that heading until the FMS captured the next airway segment.
Example Sentence 2
After takeoff we flew the assigned heading to an intercept to meet the outbound course at the proper angle.