History of Flight
On November 6, at 2236 mountain standard time, a General Atomics Predator-B MQ-9 unmanned aircraft, registration CBP113, operated from Ground Control Station GCS 3001, departed the runway after a hard landing at Libby Army Airfield, Fort Huachuca, Sierra Vista, Arizona. The flight was conducting a training evaluation mission for a Launch-Recovery Element (LRE) checkride. Prior to the exercise, the aircraft had been on a Customs and Border Protection (CBP) operational mission, and control was handed over to the training pilot and evaluator.
The aircraft performed a sequence of touch-and-go landings on runway 26. The first landing attempt was too high, leading to a 360-degree turn and a planned go-around. The first two landings used the fixed nose camera; after discussion, the second landing was smoother. On the third landing, the aircraft touched down on the nosegear and porpoised. This landing was the first using the Multi-Spectral Targeting Ball (MTS-B) payload camera. During the downwind leg, the evaluator pilot (EP) instructed the pilot to switch to the payload camera. The aircraft appeared stable on short final, maintaining a reference speed of 90 knots, reducing to about 75 knots just before touchdown on the nosegear. Recorded data showed the flare was initiated closer to the runway with less nose-up attitude than previous landings. The aircraft bounced four times, with increasing bounces and pitch excursions until the nosewheel fractured and the aircraft began sliding.
The first impact occurred at one degree nose-low attitude, producing a small pitch increase. The pilot input forward stick, and the aircraft touched down again with slightly more force, pitching up to about 5 degrees. The pilot repeated forward stick inputs, and after the third bounce, recorded data indicated the control stick moved aft about 5 degrees, but pitch attitude trended downward, resulting in an impact of as much as 15 degrees nose-down. Another pitch cycle occurred, but by then the nosewheel had likely fractured, and the subsequent impact damaged the payload ball.
The pilot reported initiating a go-around, and the EP stated he placed his hand on the control stick to ensure correct position, then pulled it aft in an unsuccessful attempt to correct the bounce. The EP noted it was possible to disengage the control stick with pressure on the trim button, but could not determine if that occurred. The EP observed the pilot had a low pitch attitude and, due to previous tailstrike events fleet-wide, pilots tend to avoid flaring much.
Airport fire crews responded after a call from the ATC Tower, and two General Atomics technicians shut off on-board batteries and engine controls.
Damage to Aircraft
The nosewheel rim fractured, and the nose tire burst. The wheel assembly separated from the nose strut. The left main gear was bent approximately halfway along the main strut, and the right main gear failed upward and outward. The MTS-B was abraded and damaged. The lower vertical stabilizer separated from the airframe. The propeller was bent, and about 10 inches of one blade separated from the propeller.
Other Damage
Small gouges in the runway from the fractured propeller blade stub.
Personnel Information
The pilot was receiving a checkride for LRE qualification. He had been recommended for the checkride after completing "Lesson 15 Checkride Prep" in the LRE syllabus, with favorable comments noting "excellent job doing the night nose camera landing." He had practiced landings using both nose camera and MTS-B infrared camera in previous lessons. He had approximately 9000 hours in manned aircraft, flying the Citation and other aircraft for CBP. He transitioned to the Predator in March 2008, with about 100 hours in the MQ-9 and was a qualified Mission Control Element (MCE) pilot.
The Evaluator Pilot (EP) was a contractor to General Atomics, having previously worked for GA on various UASs. He had over 5400 hours PIC on UASs and over 5000 landings, with over 1600 hours on the MQ-9. He was an FAA certified commercial pilot in manned aircraft.
The sensor operator was fully qualified, with 2.5 years at GA. He was certified on both MQ-1 and MQ-9, with about 1800 total hours and 460 hours on the MQ-9. He supported UAS pilots in executing checklists and callouts.
The Command Duty Officer (CDO) was an MCE rated MQ-9 pilot with over 9 years at CBP, also a certified helicopter pilot.
Aircraft Information
CBP113 was built in 2007, delivered to CBP in 2008, one of four Predator-B MQ-9 UAVs operated by CBP. The aircraft had approximately 444 flight hours prior to the accident flight. The GCS used was one of two at Libby Army Airfield. CBP113 was configured for airborne reconnaissance. The MQ-9 was not FAA certified but operated under a Certificate of Authorization. It was powered by a Honeywell TPE-331 turboprop engine.
The MTS-B payload camera was mounted on the underside of the nose, about 6 inches right of centerline and 3 feet lower than the nose camera. It had a narrower field of view and higher resolution, and was gyro stabilized, giving a different perception upon landing. Pilots described the aircraft as "glider-like" during landing.
The MQ-9 trim system allowed pilots to set trim by positioning the stick, depressing a switch on top, then releasing after returning the stick to center. Depressing the switch prevented stick movement from commanding flight control changes.
Takeoff weight was 7,827 pounds; planned landing weight was 6,400 pounds.
Meteorological Information
Weather at the time: light and variable wind, sky clear, visibility greater than 10 miles, temperature 19°C, dewpoint -10°C, sea level pressure 30.14 inHg.
Aids to Navigation
The aircraft navigated via GPS with no anomalies or RAIM warnings. No data link anomalies noted.
Communications
Communications with ATC were nominal.
Aerodrome Information
Libby Army Airfield, Sierra Vista, Arizona, is a joint-use civil/military field. Runway 8/26 was 12,001 feet long, 150 feet wide, with a 1% uphill grade west. Touchdown zone elevation 4,599 feet. Runway dry, no NOTAMs. Tower in operation; no other aircraft in the traffic area as required.
Flight Recorders
The GCS recorded about 1900 parameters, plus video from the nose camera and MTS-B. All data downloaded successfully. No audio recorded.
Wreckage and Impact Information
The first nosewheel rim piece was found on the runway about 2,300 feet from the threshold, 20 feet left of centerline. Other rim pieces found over about 100 feet. A long scrape mark started near the nosewheel impact. Five prop strike marks were found. Debris and scarring consistent with the lower vertical stabilizer contacting the runway and separating. The aircraft then swerved left and exited the runway. The payload ball was severely damaged; left wingtip scraped.
Tests and Research
Nosewheel examined at NTSB Materials Lab; no pre-existing damage or fatigue found.
Video from GCS displays was extracted and spliced to compare pilot and sensor operator views. Brief data dropouts noted but deemed playback artifacts.
USAF Mishap Analysis and Animation Facility created an animation using data logger software for visualization, including a chase-plane view and instrumentation windows.
Organizational and Management Information
CBP, part of DHS, formed the Office of Air and Marine in 2005 and began developing a UAS program. At the time, CBP operated four MQ-9 aircraft from Sierra Vista for training and border observation.
General Atomics-Aeronautical Systems Inc. manufactures unmanned aircraft including the MQ-9 Predator-B, ground control stations, and sensor hardware, and provides field support.
Additional Information
After the accident, the FAA suspended the CBP Certificate of Authorization for MQ-9 training at Sierra Vista. CBP conducted an internal review, and on December 17, 2008, the FAA reinstated the training COA. LRE training resumed on February 17, 2009.
On October 24, 2007, following a public forum on UAS safety, the NTSB issued recommendations to the FAA and CBP, which remained classified as "open-response received" at the time of the accident.