The National Transportation Safety Board (NTSB) has determined the pilot of a U.S. Customs and Border Protection Airbus AS350 B3 that crashed near Potrero, California, in December 2024 lost control during cruise flight after becoming incapacitated for reasons that could not be determined.

The NTSB’s final report, published Sept. 23, 2026, stated the pilot had severe coronary artery disease and heart damage, which increased his risk of a sudden cardiovascular event. The report noted an autopsy could not rule out a heart rhythm disturbance, heart attack, or stroke occurring shortly before death. The report also speculated he could have fallen asleep as a result of taking diphenhydramine and doxylamine, sedating antihistamines, or from fatigue from recent respiratory illness. Investigators found the evidence insufficient to determine which of these, or some other cause, led to the incapacitation.

The Airbus AS350 B3 (N617GC) departed Brown Field Municipal Airport in San Diego at about 8:56 a.m. on Dec. 16, 2024, on a routine air-support mission with only the 53-year-old pilot onboard. According to flight track data, the helicopter flew at relatively stable altitudes on a generally consistent track for one and a half hours. A little after 10:29 a.m., the aircraft began two S-turns while descending from 4,200 feet to 3,100 feet msl over 49 seconds. Vertical speed data showed descent rates of more than 12,000 feet per minute. The last data point captured for the helicopter was at 820 feet above the ground and 280 feet from the crash site. Investigators determined the helicopter hit the ground at a high rate of descent.

The Air Force Rescue Coordination Center detected the helicopter’s emergency locator transmitter (ALT) a little after 10:30 and notified CBP’s Air and Marine Operations Center. Rescuers in a search helicopter from Brown Field located the wreckage 53 minutes after the ELT activation.

The NTSB reported that after a departure call at about 9:04 a.m., the pilot made no additional radio calls or reported a problem. The weather was clear with light wind. Investigators found no mechanical malfunction, no evidence of contact with another object, and no sign of an intentional recovery maneuver. 

FAA toxicology testing detected diphenhydramine and doxylamine along with several other over-the-counter cold medications and the pilot’s prescribed blood pressure drugs. The FAA advises pilots not to fly within 60 hours of using either drug. Investigators could not determine when the pilot took the drug.

The pilot had taken sick leave on four of his six scheduled workdays in the two weeks before the crash. His wife stated the weekend before the accident he appeared to be feeling well as he spent time with family and did not have a cough. On the morning of the flight, when questioned about his fitness for flight due to a raspy voice, the pilot stated repeatedly that he was fine and had recovered from a cold.