Incident Overview
On January 27, 2014, at approximately 11:18 p.m. Pacific Standard Time, a General Atomics MQ-9 unmanned aircraft system (UAS) operated by U.S. Customs and Border Protection (CBP) and registered as CBP159 sustained substantial damage following an intentional ditching 23 miles west of Point Loma, California. The flight was conducted as a non-military public aircraft operation under Title 49 U.S.C. Sections 40102 and 40125, and a Federal Aviation Administration Certificate of Authorization. The aircraft operated under instrument flight rules inside Warning Area W-291 in visual meteorological conditions. No injuries occurred.
Generator Failure and Decision to Ditch
The aircraft was en route to its assigned operational area at flight level (FL) 280 when an audible alarm sounded, followed by warnings indicating a generator failure: "battery-sourcing current," "28 V bus - voltage approaching lower limit," and "power system/fault- payload shed." The pilot immediately reversed course and initiated the Dual Generator Failure Checklist. The checklist was completed without restoring generator operation. Throughout the flight, the pilot attempted multiple unsuccessful generator resets.
Crew analysis determined that the aircraft lacked sufficient backup battery power to sustain flight to the nearest recovery site at Fort Huachuca, Arizona—a transit that would cross populated areas. The crew elected to proceed to the Flight Termination Point (FTP) on the eastern side of Warning Area W-291 to perform an intentional ditching. Most electrical equipment remained on to preserve control power via Ku satellite communication (SATCOM).
Descent and Ditching Sequence
En route to the FTP, the pilot descended from FL280 to 5,000 feet mean sea level (MSL), then continued below a marine overcast layer at approximately 2,000 feet to confirm the FTP area was clear. After verifying no maritime traffic, the pilot positioned the aircraft south of the FTP and initiated final descent.
At approximately 600 feet MSL, the crew lost the command link due to a low voltage condition that triggered an automatic reset of the Interim Link Manager Assembly (ILMA). After about two minutes, the crew re-established the return link and found the aircraft climbing through 2,000 feet MSL on its lost-link profile (previously set to 5,000 feet MSL). The crew regained command link and positive control, then maneuvered the aircraft back toward the FTP. The pilot actuated the condition lever to stop the engine and completed the ditching. The aircraft impacted the water approximately 1.7 miles north of the FTP, destroying the aircraft.
Aftermath
A full CBP report of this accident is available in the public docket for this case.