Incident Details
A Pan American flight (PAA FLT) was conducting a visual approach and was in contact with approach control. The controller informed the flight of two aircraft ahead also on visual approach and offered vectors to clear traffic. The PAA flight elected to continue its current heading.
Sequence of Events
The two preceding aircraft were on the tower frequency, giving position advisories because the tower was closed. The PAA flight chose to remain on approach control for ASR (Airport Surveillance Radar) assistance. As the flight closed on the second aircraft, it requested vectors away. The controller stated that the targets had merged and that he was no longer seeing either of the other aircraft.
Shortly thereafter, the second aircraft was observed off the right nose slightly below at a distance of 150 to 175 feet. The PAA flight performed a climbing left turn and cleared the other aircraft. The PAA flight then circled and landed without further incident after the other two aircraft had landed.
Procedural Issues
Company procedures required the PAA flight to monitor the tower frequency for traffic and give position reports when the tower was closed. This was not done.