On January 7, 2021, a Gulfstream IV-SP (N478GA) and a Cessna Citation CJ4 (N614CJ) were involved in a near mid-air collision (NMAC) approximately 3.5 miles southeast of Montgomery-Gibbs Executive Airport (KMYF), San Diego, California. The Gulfstream was being operated by a Part 135 air carrier on an IFR flight plan and the Cessna was being operated by a Part 91 air carrier on a VFR flight plan. The Gulfstream was descending through 2,700 feet mean sea level (msl) when the pilot observed the Cessna on a converging course and initiated a turn to the right. The Cessna was descending through 3,100 feet msl when the pilot observed the Gulfstream on a converging course and initiated a turn to the left. The aircraft passed within approximately 100 feet of each other, and the Gulfstream pilot reported that the Cessna’s left wingtip passed in front of the Gulfstream’s windshield. There were no injuries to the occupants of either aircraft, and both aircraft landed safely at their intended destinations.
The National Transportation Safety Board (NTSB) determined that the probable cause of the NMAC was the Cessna pilot’s failure to see and avoid the Gulfstream, and the contributing factor was the Cessna pilot’s distraction due to a blocked radio transmission.