History of Flight
On February 19, 2009, at approximately 1318 Mountain Standard Time, a US Customs and Border Protection (CBP) General Atomics MQ-9 Predator B unmanned aircraft, registration CBP-108, experienced a hard landing and tailstrike while conducting Launch and Recovery training. The event occurred during the seventh of eight planned touch-and-go landings at Libby Army Airfield in Sierra Vista, Arizona.
The aircraft began its descent from pattern altitude of about 1,200 feet above ground level at 95 knots indicated airspeed, with autoflight modes off. Vertical speed averaged -377 feet per minute but varied significantly. At approximately 400 feet, flaps were set to 30 degrees and power reduced to 27.4%. The pilot reduced power to idle at about 6 feet altitude with a pitch of +1.5 degrees. Airspeed decreased to 74 knots as the pilot commanded nose-up pitch to 12 degrees. A tailwind component of 9 knots was computed. The instructor advised the student to flare more and add power for a go-around. A peak acceleration of +3.76g occurred, coinciding with the first hard touchdown. The instructor reported taking control as the aircraft stalled and impacted the runway. The pilot commanded a pitch up to 15 degrees, and the aircraft pitched to 17.5 degrees before a nose-down command of -3.2 degrees. At 1317:22, full power was commanded just before a second 4.8g acceleration. The aircraft's pitch was +1.5 degrees while the command was 16.7 degrees; airspeed was 71.3 knots, below the calculated stall speed of 74 knots. The aircraft bounced and entered heavy pitch and roll oscillations for about 15 seconds. At 1319:36, airspeed increased above stall speed and the aircraft climbed. The instructor maintained control and climbed to pattern altitude. The sensor operator inspected the aircraft via payload ball and saw no catastrophic damage. The instructor completed a full-stop landing on runway 26 with no further damage or injuries.
Damage to Aircraft
The vertical fin, including the rudder and tailwheel, was damaged, affecting flight control. Propeller blades were bent, the left main landing gear wheel hub exhibited crush damage, and there were two cracks in the lower cowl.
Personnel Information
The student pilot held FAA Airline Transport Pilot and U.S. Military pilot certificates with multi-engine land and instrument ratings. He had 2,325 total hours, with 1,084 hours as pilot in command, and 76 hours on the MQ-9. He held a current FAA First Class medical certificate without limitations.
The instructor pilot held FAA Commercial Pilot and Flight Instructor certificates with instrument multi-engine land ratings. He had 4,650 total hours, including 322 hours as an MQ-9 instructor. He held a current FAA Second Class medical certificate without limitations.
Aircraft Information
CBP-108 was built in June 2007 and delivered to CBP in July 2007. It was one of six Predator B MQ-9 UAVs operated by CBP and had approximately 561 flight hours prior to the accident. The ground control station used was located at Libby Army Airfield. The aircraft was configured for airborne reconnaissance. It was not FAA certified but operated under a Certificate of Authorization. It was powered by a Honeywell TPE-331 turboprop engine. Maximum gross weight was 10,500 pounds; estimated weight at the time was 8,089 pounds. No maintenance conditions relevant to the accident were found.
Meteorological Information
Weather conditions included light and variable wind, clear skies, visibility greater than 10 miles, temperature 17°C, dewpoint -8°C, and barometric pressure 30.20 inches of mercury.
Aids to Navigation and Communications
The aircraft navigated via GPS with no anomalies. No issues with data uplink/downlink or communications were noted.
Aerodrome Information
Libby Army Airfield in Sierra Vista, Arizona, is a joint-use civil/military field. Runway 8/26 is 12,001 feet long and 150 feet wide, with a 1% uphill grade to the west. The runway was dry, and the ATC tower was in operation with no other aircraft in the traffic area.
Flight Recorders
The ground control station data logger recorded approximately 1,900 parameters of command and status information. All data was downloaded successfully. No audio was recorded.
Tests and Research
General Atomics – Aeronautical Systems Inc. reviewed the data logger files to determine the sequence of events, as reflected in the History of Flight section.
Organizational Information
US Customs and Border Protection, an agency of the Department of Homeland Security, formed the Office of Air and Marine in 2005 to manage aviation assets. At the time of the accident, CBP operated six MQ-9 aircraft from Sierra Vista for training and border observation. General Atomics – Aeronautical Systems Inc. manufactures the MQ-9 and related systems.
Additional Information
Following a November 2008 accident, the FAA suspended CBP's Certificate of Authorization for MQ-9 training. After an internal review, the FAA reinstated the training COA on December 17, 2008, and CBP resumed LRE training on February 17, 2009. The NTSB had issued recommendations to the FAA and CBP in October 2007, which remained classified as "open-response received" at the time of this accident. CBP subsequently prohibited tailwind landings, increased training oversight, and implemented additional training improvements. General Atomics recommended safety changes including compliance with approach speeds and system improvements.