The U.S. Air Force on Tuesday released their investigative report into the fatal crash of a Thunderbirds pilot last April detailing the cause and events surrounding the accident.
Thunderbirds slot pilot Major Stephen Del Bagno, 34, died during a training flight maneuver over the Nevada desert as the squadron prepared for their next air show. After experiencing a negative 2-G (gravity) maneuver followed quickly by a positive nearly 9-G maneuver, Maj. Del Bagno past out only to regain consciousness too late to avoid the crash.
The USAF Aircraft Investigation Board, led by Brig. General Case A. Cunningham, states in their report that Maj. Del Bagno was not at fault for the crash. Gen. Cunningham’s final words confirmed the pilot simply could not transition his body during this push-pull effect from a “diminished tolerance to positive G’s induced by the physiology of exposure to negative G’s”.
The squadron of six F-16 Fighting Falcon aircraft were in the midst of practicing one more day over the desert floor located just north of their Las Vegas home at Nellis Air Force Base. The Thunderbirds were scheduled to depart Nellis the next day for their next air show site at March Air Force Base in California.
Under good weather conditions, the aircraft performed the High Bomb Burst Cross maneuver — a favorite with air show crowds. As the aircraft fly in different directions afterwards, the jets then began their return to formation known as the High Bomb Burst Rejoin.
It was at this moment that Thunderbird 4 pilot Major Del Bagno experienced the negative 2-G force to an extremely high 8.5 G’s. He blacked out for several seconds before regaining consciousness a split second prior to the crash. He never attempted to eject.
At impact, his airspeed was recorded at 419 knots with his F-16C at an attitude of “57 degrees nose low with 89 degrees of left bank”. The forces on the aircraft were recorded at 4.5G’s.
“As (Maj. Del Bagno) initiated the Split-S at 1028:59 (a.m. local time), (he) selected idle power on the engine throttle and pulled back on the control stick to drop the nose of (Thunderbird 4) toward Thunderbird 1 to affect the rejoin. This operation took the Thunderbird 4 from -2.06 G’s in inverted flight to a maximum of +8.56 G’s at 1029:03 a.m.,” the official investigative report outlined.
“Approximately one second later at 1029:04 a.m., the pilot experienced a G-LOC and stopped providing deliberate flight control inputs with the aircraft at 68 degrees nose low. The pilot began a period of absolute incapacitation with the aircraft accelerating through 356 knots calibrated airspeed and rapidly descending through 6,556 feet mean sea level.”
“For approximately the next five seconds, the pilot remained in a state of absolute incapacitation and made no deliberate flight control inputs with the aircraft accelerating through 415 knots at 60 degrees nose low and 406 feet. At 1029:09 a.m., the pilot began deliberate flight control inputs as he transitioned from absolute to relative incapacitation. The aircraft impacted the ground at 1029:10 a.m. fatally injuring the pilot.”
Seconds later, the Range Safety Officer and the Thunderbird 6 opposing solo pilot Maj. Matt Kimmel radioed, “Knock it off!”. Thunderbird 5 lead solo pilot Maj. Whit Collins then climbed high over the crash site to look for a parachute.
One minute following the crash, Thunderbird leader Lt. Col. Kevin Walsh ordered the two solos to retun home to Nellis as they reported they were low on fuel. He then told Thunderbird 2 and 4 to return to Nellis. Lt. Col. Walsh remained above the crash site as emergency vehicles arived minutes later.
During the last 90 days with the Thunderbirds, the report states that Maj. Del Bagno piloted the F-16C a combined 79 times and logged 92.9 hours. Del Bagno joined the Thunderbirds five months earlier.
The report adds weather was not a factor in the accident with calm winds, a 10 mile visibility, and “a few clouds at 14,000 feet (and) a broken ceiling at 19,000 feet”.
(Charles A Atkeison reports on aerospace and technology. Follow his updates via social media @Military_Flight.)