|Air Safety Committee Advisory 99/03
Swissair Flight 111 UPDATE
May 1st, 1999
We, the IFALPA Air Safety Committee, would
like to present you with some valuable factual information concerning the sr111
investigation in Halifax.
We would like to begin by saying that progress is being made every day, but
due to the slow nature that constitutes aircraft reconstruction, this progress
is not evident to those outside the investigation.. However we assure you that
the TSB is doing a thorough and very professional job. To date they have recovered
approximately 88% of the aircraft by weight. The TSB is reconstructing the first
10 metres of the forward fuselage to just past the L1 and R1 doors, as well
as the forward galleys, the cockpit wiring runs and the inflight entertainment
system wiring runs. Before we list some facts that were recently disclosed,
here are a few interesting points that we have learned from this investigation.
- An arcing event also known as ticking fault, can disburse a very large current
that can cause a fire! YET IT WILL NOT POP THE CIRCUIT BREAKER.
- Under certain conditions, if a circuit breaker has popped and the wire insulation
in that circuit has been damaged, RESETTING THE CIRCUIT BREAKER MAY CAUSE
THE WIRE INSULATION TO BURN.
Following is additional information on the accident:
- There was a fire in the ceiling area of the cockpit of sr111. Various methods
are being used to try and determine fire and smoke propagation in the cockpit
and forward cabin areas.
- The origin of the fire is still unknown, but one possibility is heat caused
by an electrical short or arcing.
- From inspection of the damage to the FO’s seat and harness, it was determined
that he was in his seat.
- From inspection of the damage to the Captain’s seat and harness, we could
not determine that he was in his seat.
- There have been several AD’s regarding wiring issues after examination of
the aircraft wreckage.
- The TSB issued a safety advisory regarding overhead cockpit wiring in the
- The process is going to take at least another year before a final report
is issued as to the cause. The TSB is looking at all issues and inspecting
all the systems to best determine the status of the systems at aircraft impact.
All the facts need to be gathered and analysed to determine the best possible
recommendations to help prevent another accident of this type.
We would also like to take this opportunity to present you with issues that
the IFALPA investigative team feels need to be addressed, in present as well
as future aircraft.
- Design of checklist coordinated with electrical system to remove as much
electrical power as possible from the aircraft, as soon as possible and reducing
the load down to a level of “essential power”.
- Some type of cockpit fire detection and fire extinguishing system available
to the crew whilst in their seats and attached to the oxygen system.
- An integral power supply for the standby horizon.
- A wiring system, separated by location, powering the Captain’s flight instruments,
communications and navigation.
- Checklist design. We believe that font type, font size, color of the print
and color of the background of the checklist used by the crew was not optimal.
- A Smoke/heat detection system in avionics compartments.
We hope that this will dispel some of the rumours and clarify what is happening
in Nova Scotia.
Air Safety Committee – sr111 team