Flight 232 from Denver to Philadelphia with a stop
in Chicago. The DC-10, a wide-bodied jet with three
engines—one on each wing and one in the tail—
took off a little after 2:00p.m.central daylight time.
The three-member flight crew consisted of Captain
Alfred Haynes; First Officer William Records, the
copilot; and Second Officer Dudley Dvorak, the
flight engineer. About an hour after takeoff, a fan
disk in the center engine broke in two, shattered the
engine, blew through the engine case, and tore
holes in the tail section of the plane. It punctured
all three hydraulic systems, allowing the fluid to
run out.
None of this damage was known in detail at the
moment of the incident, but the flight crew felt a
sharp jolt running through the plane. The copilot,
who was at the controls, noticed that the airliner was
off course and tried to correct the course with the
controls, but he found the plane unresponsive. The
crew also discovered that the autopilot was off, that
the engine in the tail indicated a malfunction, and
that the three hydraulic systems had lost all pressure.
Although the three systems were designed to back
one another up, their collective failure meant that
none of the usual wing or tail controls on the aircraft
would operate, creating a severe emergency situa-
tion.
The fan blade had broken and locked the con-
trols while the plane was in a slight right turn. The
hydraulic loss meant the plane was in a circular pat-
tern while descending about fifteen hundred feet
with each cycle. A DC-10 flight instructor, Dennis E.
Fitch, was a passenger on board and offered to help.
Eventually, he managed to stem the downward cycle
a bit by running the two remaining engines at differ-
ent speeds to steer the plane and gain or lose alti-
tude. He also managed to lower the landing gear,
but he was not able to restore the critical hydraulics.
The crew notified air traffic controllers, who indi-
cated that the closest sizable airport was at Sioux
City, Iowa. An emergency landing was organized
there in the roughly thirty minutes available be-
tween the airborne incident and the crash landing.
The crew dumped the plane’s excess fuel, and every-
one took care to avoid allowing the plane to pass
over populated areas. This was very difficult, as the
plane could make only right-hand turns. On final
approach, the crew realized they could not attempt
landing on the airfield’s longer runway and there-
fore notified the tower that they would try to reach a
shorter runway on which the scrambled fire trucks
had parked. Fortunately, the trucks were able to va-
cate the runway in time, but this situation delayed
their response to the fire that resulted from the
plane’s impact.
A DC-10 would normally land at a speed of about
140 knots while descending at 300 feet per minute.
The best the crew could do was to land their crippled
plane at 240 knots while descending at 1,850 feet per
minute. This resulted in a crash, but not as severe a
crash as one might have expected for such a seri-
ously crippled plane. A strong gust of wind blew the
plane to the right of the runway and caused the right
wing to hit the ground first, causing fuel to leak and
ignite. The tail broke off first, and the rest of the
plane bounced repeatedly, eventually rolling over
on its back and sliding sideways into a cornfield next
to the runway.
Of the 296 people aboard, 185 survived. Most of
the 111 deaths resulted from the impact, but some
were the result of smoke inhalation as the fire en-
gulfed the section above the wings. Most survivors
had been sitting ahead of the wings, and some were
lucky enough to walk out of the crashed plane and
into the cornfield unharmed.
A number of factors allowed for a better chance
of survival than might have been expected from
such a seriously damaged plane. The inherent crash-
worthiness of newer wide-bodied air transports
played a part in the relatively high survival rate, as
did the shallow angle of descent as a result of the
crew’s heroic efforts to land the plane as safely as
possible. The incident occurred in daylight in good
weather on the one day of the month when the Iowa
Air National Guard was on duty at Sioux Gateway
Airport. It also occurred at a time of day when extra
personnel were available at both a regional trauma
center and a regional burn center.
The subsequent investigation revealed that the
fan blade broke because of fundamental weakness in
its design. The weakness was corrected as a result.
Additional investigation indicated that the weakness
was missed during maintenance checks. The critical
hydraulic failure was remedied by installing special
fuses to prevent fluid loss in all hydraulic systems.Impact The Sioux City plane crash resulted in sev-
eral engineering improvements for the DC-10 but
had an even greater impact on procedures for train-
ing flight crews for emergencies. The Sioux City,The Eighties in America Sioux City plane crash 875