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click here for radio transcript
Aloha
Airlines flight 234 lifted off from Hilo
airport on the main island of Hawaii just
before 1:30pm bound for Honolulu, the
company's base. Captaining the flight that
day, April 28, 1988, was Robert
Schornstheimer and First Officer Madeline
Tomkins, who was at the controls during
that leg. Also on board the 737 that
afternoon were three cabin crew members
and eighty-nine passengers. 234 reached
it's cruising altitude of FL240 twenty
minutes into the flight, while passing
abeam the north-western tip of the island.
Just after levelling off, there was a loud
explosion followed by screaming and debris
filling the cockpit and cabin. The Captain
quickly took the controls and both flight
crew members donned their oxygen masks.
Looking back, the flight crew could see
that the cockpit door had been torn off
and they could see blue sky through the
hole.
Passengers Scramble to Exit 243
Though the
aircraft seemed somewhat unstable, it was
responding to control and the Captain
immediately began an emergency descent
towards Kahului airport on the island of
Maui. First Officer Tompkins began calling
ATC to report the diversion and emergency,
but because of the noise, she could not
hear any reply. As they were approaching
Kahului, Tompkins switched over to the
tower frequency and was able to make
contact. The tower then mobilized
emergency equipment. 243 continued to
approach from the south and through the
controls were still sluggish, the aircraft
was flying well and had been slowed to
approach speed.
The gear was selected
down and though the main gear down
position light illuminated, the nose gear
did not. Tompkins selected the manual
extension and though the nose gear light
did not illuminate, the gear unsafe light
did go out. The crew was then under the
impression that they would be landing
without the nose gear. Having lined up
with the runway with flaps at the 5
position, the Captain then asked for flaps
15, which caused the aircraft to become
markedly less controllable. Tompkins then
retracted the flaps back to 5 and
consulted the flight manual for the new
Vref speed, which she determined to be
152kts.
Upon
slowing through 170kts, however, the
captain found the aircraft to again become
uncontrollable, so it was decided to land
at 170kts. The tower then called 243 and
reported that it looked as if all gear
were in the down position. As the Captain
advanced the throttles to keep up the
speed, he found that the port engine had
failed. He attempted to restart it, but to
no avail. Powered by the only remaining
engine, 243 touched down smoothly on
runway 2 and braked to a stop, the nose
gear holding up throughout the touchdown.
The crew quickly opened up the aircraft
and was able to evacuate the passengers.
It was only then that they realized that
flight attendant Clarabelle Lansing had
been ejected from the aircraft during the
explosive decompression. Fortunately,
though many other passengers were injured,
some severely, everyone else survived.
It was
obvious that 243 suffered a devastating
explosive compression, tearing off a
section of the forward fuselage 18 feet
long from the port floor level to the
starboard floor level. The leading edges
of both wings and tail fins showed denting
from debris impact. The engine cowls and
first stage fan blades showed impact
damage as well. Debris had lodged in the
leading edge of the starboard wing near
the engine pylon. This prevented the slat
from extending, causing the control
difficulties when the crew attempted to
configure for landing. Broken starter and
power lever cables which ran through the
leading edge of the port wing were broken,
which caused the loss of the port engine.
The nose gear light bulb had burnt out.
Debris Jammed in Slats Near Engine
A passenger later
recalled that upon boarding the aircraft
at Hilo, she had noticed a crack in the
fuselage running through a row of rivets
just aft of the door. She did not mention
it to the crew, believing that they would
not take her seriously. The aircraft
involved in the accident was 19 years old,
having begun service with Aloha in 1969.
In fact, the aircraft had completed 89,680
flight cycles, the second highest number
in the entire worldwide fleet of 737
aircraft. However, because most Aloha
flights were of short duration, the
maximum cabin pressure differential was
not always reached so the equivalent
number of cycles was significantly less.
The aircraft had been involved in one
other incident involving clear air
turbulence, but no structural damage was
recorded. In the early production of the
737, including the aircraft involved in
the accident, Boeing used a cold bonding
procedure to join fuselage skin joints.
However, this technique
was discontinued due to possible corrosion
if moisture was allowed into the bond.
Examination of the several pieces of the
aircraft's skin showed many fatigue cracks
along joining rivets as well as moderate
corrosion along most of the joints. One
joint had disbonded completely.
Investigators concluded that the skin
separation began near floor level on the
port side at about row 3. Investigators
found that, because of Aloho's high flight
cycles, it's inspection schedule was not
sufficient for detection of fatigue
cracking.
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