Swissair Flight 551
Ten minutes after Swissair Flight 551 left Munich for Zurich on 16 October 1993, an overheating emergency power switch filled the MD-81's cockpit with dense smoke and knocked out the captain's instruments. The pilots flew back to Munich almost blind and landed 13 minutes after asking to return, and all 95 people on board survived the evacuation, 15 of them with minor injuries.
The sequence of events
All times local
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09:35
Takeoff from Munich
With 88 passengers and 7 crew, the MD-81 was cleared for takeoff from runway 26L for the short flight to Zurich and levelled at flight level 180 at 09:42.
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Watch this moment · 3:32
09:45approximately
Smoke from the overhead panel
The captain noticed an unusual smell, and smoke appeared above the landing light switches. A flight attendant at the cockpit door pointed to the overhead panel as the source, and the crew asked to return to Munich immediately.
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Watch this moment · 13:20
Emergency declared
Working through the "Electrical smoke in cockpit" checklist, the crew switched off the right generator. Almost all of the captain's instruments failed and the smoke thickened, and the crew declared an emergency.
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09:53
"I can't fly anymore."
With his instruments failing intermittently, the captain handed control to the first officer. Smoke deposits made it impossible to read charts, so the crew had to ask air traffic control for the ILS frequency.
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09:55 to 09:58
Approach in smoke
Radar vectors brought the aircraft onto the ILS for runway 08R. The runway kept disappearing in the smoke; the captain took control again near 500 ft, guided by the first officer's speed calls, while the first officer fanned smoke away with the checklist.
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Watch this moment · 25:36
Landing and evacuation
The aircraft landed normally, but the crew lost all outside view during the roll-out and braked hard. Everyone evacuated over three slides and the wings; 14 passengers and one flight attendant were slightly hurt.
Key facts
| Aircraft | McDonnell Douglas MD-80 |
|---|---|
| Aircraft variant | MD-81 (DC-9-81), registration HB-INH |
| Flight number | 551 |
| People who died | 0 |
| People on board | 95 |
| Were there survivors? | Yes |
| Phase of flight | Cruise |
Official finding · Flugunfalluntersuchungsstelle beim Luftfahrt-Bundesamt (FUS), Germany
the incident was caused by a massive smouldering fire in the emergency power switch, which failed through mechanical and electrical overload; the tail slide did not deploy because a transport safety pin had not been removed when it was installed.
Questions and answers
What caused the smoke on Swissair Flight 551?
The emergency power switch in the overhead panel overheated and smouldered. German investigators found it had failed through mechanical and electrical overload; its worn contacts heated up until wiring and terminal blocks around it charred.
Did everyone survive Swissair Flight 551?
Yes. All 88 passengers and 7 crew survived. During the evacuation 14 passengers and one flight attendant were slightly injured, most of them sliding off the wings.
Why didn't the crew finish the smoke checklist?
After the right generator was switched off, the captain's instruments failed and the smoke became so dense that the checklist could not be read. The video notes that its final step, opening the cockpit windows, might have fed the fire with oxygen.
How is Swissair 551 related to Swissair 111?
Both were Swissair flights with smoke in the cockpit. Flight 551 landed 13 minutes after asking to return. Five years later Swissair Flight 111 was lost off Nova Scotia, and smoke procedures were rewritten to tell crews to consider landing immediately at any point in the checklist.
What changed after the investigation?
The investigators recommended a life limit of 10,000 operations for the switch on DC-9 series aircraft, and moving high-current relays and wiring out of the cockpit overhead panel. McDonnell Douglas set the 10,000-cycle limit by service bulletin, and the FAA made it an airworthiness directive.
Sources: The facts and written text on this page come from the 1 video on this page, by Mentour Pilot.
