Regional Jet 200 ER/LR (CRJ200)
Air Traffic Control Fully Certified
ATC Issue All Types
General None Reported / Taken
Procedure
LGA advertised LDA-A approach. A B737-800 vectored across LDA-A final approach course and then cleared for a visual approach (VAP) to Runway 22. A CRJ-200 on downwind being vectored to follow the B737-800. Instead of proceeding visually direct to the runway with weather not a factor; the B737-800 unexpectedly turned away from the runway back towards the LDA-A final approach course. Separation was lost with the CRJ-200 who was being vectored downwind to the expected VAP flight path. Recommendation; when cleared for a visual approach; aircraft should be required to fly the most direct route to the runway when practical. When unable to do so; pilot should inform ATC of their intentions.
N90 TRACON Controller described a loss of separation event between two air carrier arrivals when the first; cleared for a visual approach; made an unexpected turn causing the event.