Definition
An RNAV path and terminator leg type that defines a specified course the aircraft flies until it intercepts the next leg in the procedure. The CI leg has no fixed endpoint of its own — it terminates wherever the aircraft crosses the following leg's course.
Plain English
A leg that tells the aircraft to fly a particular heading-like course until it runs into the next leg, and then turn onto that next leg. The end point isn't a named place — it's wherever the two paths cross.
Context Anchor
Seen in instrument procedure design and in flight management system coding for departures, arrivals, and approaches.
Derivation
The name describes the leg literally: a Course flown to an Intercept of the next leg. The two-letter code 'CI' is part of the ARINC 424 standard, which uses two-letter codes (CF, CI, CR, VA, etc.) to label every type of path and terminator leg in a coded procedure.
Why Pilots Care
It ensures the autopilot or FMS captures the next segment of the procedure smoothly without overshooting the intended track.
Analogy
It is like driving straight down one road until you reach the road you need to merge onto. The endpoint is the merge, not a street address.
Intuition Check
Do not read course as a class or lesson here; it means the direction of travel over the ground. Do not read intercept as a military action; it means meeting and joining another published path.
Example Sentence 1
After takeoff, the SID coded a CI leg, so we flew the published course until the FMS turned us onto the next airway segment at the intercept.
Example Sentence 2
During the missed approach, the CI leg allowed the aircraft to join the holding pattern entry course.