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team at [email protected]Attrition
Repor t
G-LOC caused fatal
Thunderbirds F-16C crash
IR COMBAT Command
has released the Accident
Investigation Board (AIB)
report into the fatal crash of a
Thunderbirds F-16CM in April
this year (see Attrition, June,
p94), identifying g-induced loss
of consciousness (G-LOC) as
the cause of the accident.
The report, made public on
October 16, identified the
aircraft as serial 91-0413,
flying as ‘Thunderbird 4’.
On April 4, the mishap pilot
(MP), flying F-16CM 91-0413,
assigned to the US Air Force
Air Demonstration Squadron,
the Thunderbirds, 57th Wing,
Nellis Air Force Base, Nevada,
engaged in a routine aerial
demonstration training flight at
the Nevada Test and Training
Range (NTTR) near Creech AFB.
During the flight, at about
1029hrs local time, the mishap
aircraft (MA) impacted the
ground and fatally injured the
MP, Maj Stephen Del Bagno,
without an ejection attempt.
The mishap mission had been
planned and authorised as
a practice of a Thunderbirds
aerial demonstration in the
south part of the NTTR.
The flight was a standard
formation for a Thunderbirds
aerial demo: six F-16CMs
(‘Thunderbirds 1 to 6’).
The flight departed Nellis AFB
at approximately 0950hrs local
time. During the High Bomb Burst
Rejoin, an aerial manoeuvre near
the scheduled end of the aerial
demonstration training flight, the
MP flew the MA for approximately
22 seconds in inverted flight
between 5,500 and 5,700ft (1,676
and 1,737m) above ground level.
During this time, the MP
experienced a change in force
due to acceleration. While
experiencing -2.06g in inverted
flight, the MP initiated a
descending half-loop manoeuvre
(split-S). After five seconds in
the split-S, the MP attained
a maximum +8.56g. The MP
experienced G-LOC and absolute
incapacitation at the end of
that five-second period.
For approximately the next
five seconds, the MP remained
incapacitated and made no
deliberate flight control inputs
as the MA accelerated towards
the ground. Approximately one
second prior to ground impact, the
MP began deliberate flight controlinputs as he transitioned from
absolute to relative incapacitation.
The MA impacted the ground
at 1029hrs local time at 419kts,
57° nose low with 89° of left
bank and a descent rate of
39,750ft (12,116m) per minute with
maximum control stick input and
high engine power setting. The
MP was fatally injured on impact.
The Range Safety Officer made
the radio call “4, recover” just
as the MA impacted the ground.
Both the RSO and ‘Thunderbird
6’ then called “Knock it
off” on the radio to cease
demonstration manoeuvres.
The AIB president found, by
a preponderance of evidence,
the cause of the mishap was
the MP’s G-LOC during the
split-S portion of the High Bomb
Burst Rejoin manoeuvre.
Additionally, the president
found two factors substantially
contributed to the mishap: (a)
the MP’s diminished tolerance
to positive ‘g’ induced by the
physiology of the MP’s exposure
to negative ‘g’ (‘push-pull effect’);
and (b) an associated decrease
in the effectiveness of the MP’s
anti-g straining manoeuvre
under those conditions.Above: F-16CM ‘Thunderbird 4’ in a four-ship formation while air-to-air refuelling over the eastern US on July 30. Flying
as ‘Thunderbird 4’, F-16CM 91-0413 crashed on the Nevada Test and Training Range on April 4, killing the pilot. USAF/
Airman 1st Class Alan Ricker
Right: ‘Thunderbird 4’ pilot Maj Stephen Del Bagno at Nellis AFB during a team practice on January 26. He was killed in
the crash of ‘Thunderbird 4’ on April 4. USAF/Master Sgt Christopher Boitz
A
90 // DECEMBER 2018 #369 http://www.airforcesmonthly.com