events. No accident like the 1998 crash of Swissair
Flight 111 occurs in a vacuum. Related cases, with less deadly
outcomes, often can be found, as in these incidents below:
22, 1996, British Airways B747-400 over Abbeville,
France. From the UK's Air Accidents Investigation Branch (AAIB)
report of this incident (Bulletin No 3/96, Ref. EW/G96/01/07)
these extracts pertain:
seat 37K drew attention of cabin staff to 'sparks' coming out
of floor level cabin conditioning vent, with an acrid burning
"It was decided
to remove the cabin trim panel ... as it was removed the electrical
loom aft of the window suddenly emitted flames which reached up
to the overhead lockers. The first officer immediately attacked
the fire with a BCF extinguisher. He
then contacted the flight deck and called for all power to be
fire had occurred in a bundle of electrical cable ... [which was]
part of a loom, the bulk of which originated from power distribution
panels ... in the main electronic center ... The loom in the sidewall
ran between two insulation blankets." "The heat generated
would not have readily dissipated."
"Two circuit breakers
... had not tripped ... these were 25 amp units, as opposed to
the 2˝ amp breakers specified in the diagram"
Although not an MD-11
like the Swissair jet, this incident had a number of essential
elements in common:
Fire (sparks and smoke).
A "Pan" call.
Charred wiring in the main electrical
Burning blankets (see photo).
Hidden fire in a space with no detection
Power was initially killed – but later
restored (when power was restored to the wiring, the fire flared
Globs of melted metal from the arcing.
Circuit breakers did not protect (and
later were found to be rated incorrectly 1,000 percent higher
than they should have been, and were installed after the aircraft
was delivered from the factory).
Much aromatic polyimide wiring in
the airplane, which arcs with explosive effect.
28, 1997, Virgin Atlantic B747-200 enroute from Washington,
D.C., to London. From the UK's Air Accidents Investigation Branch
(AAIB) report of this incident (Bulletin No 10/97, Ref. EW/C97/4/3)
these extracts pertain:
As it approached Halifax, Nova Scotia, the cabin crew in
the first class section saw smoke and sparks coming from an overhead
panel above the beautician's table, which was fitted as part of
this operator's interior layout. No passengers were in the area
at the time, which was curtained-off, and they remained unaware
of the occurrence. The Flight Engineer investigated. Dropping
the two Passenger Service Unit panels nearest to where the cabin
crew had seen the smoke and sparks, he could see evidence of blackened
wires and paint discoloration. He also examined the circuit-breaker
panels and found that two had tripped - P14 'Ceiling control'
and P15 'Light window right'. The loom comprised about 50 wires,
the majority of which had melted at the same location, associated
with a 'P' clip which had also partially melted. Secondary damage
to a gasper air pipe and sooting/heat damage to adjacent structure
and trim panels was also noted. It was evident that the fire had
the loom in the area of the overheat was too badly burned to identify
which individual wire had initiated the sequence. The
airline uses third-party maintenance. A
modification had been embodied to the lighting in the affected
section which involved introducing new wires into [the] loom.
A considerable amount of 'fresh' debris such as
swarf, a solid fastener, a stiffnut and a drill bit was found
in the area which had been subject to modification. Chafing or
wire-stripping (on pulling the new wiring through the ‘P’ clip)
was blamed, however the fire had destroyed any evidence.
Again, parallels and contrasts
to the Swissair disaster:
Wiring installed as part of a modification
(and Third Party Maintenance or Modification).
A Third Man available to actively
investigate (remove panels), equate systems losses to CB trips
and rapidly resolve the action required (Flt Engineer)
Whole wiring bundles (looms) taken
out at once by fire (evidence of fresh metal swarf and drilling
debris left in situ)
Approaching Halifax - but no thought
of an immediate landing to examine the situation from the safety
of the ground.
Fire had self extinguished but only
because a mylar blanket wasn’t present (in that area) to propagate.
22, 1998, Air2000 B757- 200 enroute from Larnaca
Cyprus to Manchester UK. From the UK's Air Accidents Investigation
Branch (AAIB) report of this incident (Bulletin No 10/98, Ref.
EW/G98/6/6) these extracts pertain:
FL 255 there was a loud bang and a shower of sparks which emanated
from the overhead panel. Simultaneously, the commander's air speed
indication reduced to zero' his altimeter OFF flag appeared and
multiple OFF flags appeared on his radio distance magnetic indicator
(RDMI); the FO [first officer] ... retained control of the aircraft
which he leveled at FL 270. By this stage a number of cautionary
and advisory messages had appeared on the engine indication and
crew alerting system (EICAS) display. The commander selected the
alternate air data sources, which restored his ... altimeter.
Meanwhile his VOR/DME controller display had gone blank, the center
ILS had failed and multiple OFF flags had appeared on the standby
attitude indicator which eventually toppled." The commander
completed the appropriate drills for the following EICAS messages:
'Spoilers', 'Left Yaw Damper' 'Standby Bus Off'. He was unable
to restore power to the standby bus and since
both the main and the Auxiliary Power Unit (APU) batteries were
discharging he reset the standby power selector
to 'Auto' in accordance with the drill. During the return to Larnaca
the commander's flight director and the auto throttle failed and
when descending through 5,000 feet the 'Right IRS DC Fail' message
appeared on the EICAS and later a 'APU Batt No Stby' appeared.
Two wires above the pilot’s head had chafed against a bonding
lead, tripping the AC STBY Bus breaker and killing many systems.
Other aircraft in the same fleet were also found to have inadequate
Again, parallels and
contrasts to the Swissair disaster:
Multiple simultaneous (but wholly
disassociated) ongoing systems emergencies associated with a single
initial explosive arcing event.
Problem for the above development
– complex drills for unrelated malfunctions can have a mutually
compounding effect (cf the result of SR-111 crew turning off cabin
exhaust fans -in accordance with the checklist- leading to the
fire propagation reversing its direction of travel into the flight
Faulty routing, support and improper
stand-off of wires
Captain loses most of his critical
normal and standby flight instruments…plus some avionics
Crew declared an urgent (but not emergency)
PAN situation (only) and didn’t upgrade it - despite continuing
manifestations of elec failure.
Overweight landing carried out
Even the standby attitude indicator failed. All this stemmed from two
wires shorting out to each other.
4, 1998, BAC 1-11,
during cruise between Belfast and Birmingham. From
the UK's Air Accidents Investigation Branch (AAIB) report of this
incident (Bulletin No 2/98, Ref. EW/C98/1/1) these extracts pertain:
"Flight crew heard
a series of 'popping' sounds and observed smoke coming
from the 'hat rack' stowage area behind the captain's seat."
attendant ... saw an orange flame ... and fired a ... burst of
extinguishant into the area ... but it reignited and two additional
bursts ... were needed."
the flight deck door, the flight crew donned their oxygen masks
and transmitted 'Mayday.' " "A one-inch gap existed
between the rear of the top shelf and the fuselage trim panel,
which had allowed the oxygen mask pouch to fall onto the cables
that were connected to the rear of the relay receptacle."
"The relays ...
formed part of a modification to the cabin lighting system."
"The pouch acted
as a thermal insulation blanket such that the normal amount of
heat energy ... could not be dissipated at its usual rate, leading
to elevated temperatures and eventual combustion of the pouch
material and cable insulation.
"There would have
been no significant change n the current passing through the cables,
thus explaining why the associated circuit breakers did not trip."
noise heard by the crew was not fully explained, but ...was probably
due to the pouch material combusting."
Again, elements in
common with the Swissair crash:
A post production modification.
Breakers not tripping.
Arcing, burned material resulting
from a debris deposit
and a diversion to an immediate landing.
All told, that makes
four precursor events not long prior to the Sept. 2, 1998, in-flight
electrically-stoked fire that downed Swissair Flight 111. Different
aircraft, but common circumstances and common latent hazards.
Four strikes, then death.*
Another case of wiring sandwiched next to flammable material,
burned insulation blankets and circuit breakers which did not
trip. In this case, the breakers installed were of the incorrect
rating. Source: AAIB