Gulfstream GIV - UNDESIGNAT N0 incident near Las Vegas, Nevada

Probable cause

The Federal Aviation Administration's (FAA) inadequate procedures, which did not require specific separation between aircraft operating on nonintersecting runways where flightpaths may intersect and led to an airborne conflict between two aircraft. Contributing to the incident was the FAA's failure to correct a known procedural deficiency that had previously caused repeated hazardous intersecting flightpath events.

NTSB analysis

A Boeing 737 (737) executing a go-around from runway 25L and a Gulfstream 4 that had just departed from runway 19R experienced an airborne conflict. When passing over runway 25L, the 737 pilot announced his intention to go around because the airplane was encountering a 20-knot tailwind. The tower controller responsible for runway 25L acknowledged the report, immediately advised the pilot of traffic "just lifting off" from runway 19R, and instructed the pilot to report the traffic in sight. The tower controller then instructed the pilot to fly the runway heading and climb to 7,000 ft. The pilot read back the clearance and reported the traffic in sight. The controller told the pilot to maintain visual separation from the traffic. The 737 subsequently completed another approach and landed.

After the Gulfstream 4 departed, the tower controller responsible for runway 19R issued a traffic alert to the pilot, indicating that the 737 was "off your left going around off 25," and instructed the pilot to "stay low." The pilot responded that he had the 737 in sight. The controller transmitted, "maintain visual separation, he's climbing to 7,000, stay low." The pilot acknowledged the instruction. Fifteen seconds later, the Gulfstream pilot stated, "we're getting an RA [resolution advisory] we're climbing at this time." Review of Federal Aviation Administration (FAA) radar data showed that the minimum separation between the two aircraft following the RA was about 0.21 nautical mile laterally and 400 to 500 ft vertically.

At the time of the incident, the FAA did not have procedures requiring specific separation between aircraft operating on nonintersecting runways where flightpaths may intersect despite the occurrence of several previous similar incidents. Following this incident and another similar incident, the FAA amended FAA Notice 7110.65, "Air Traffic Control," by adding paragraph 3-9-9, "Non-Intersecting Converging Runway Operations," which directed changes in converging runway operations to prevent similar reoccurrences.

Text from the NTSB. Open the NTSB docket for OPS13IA071 for the full record.