David Learmount's synopsis of the Tranportation Safety Board of Canada's report on the 1998 Swiss Air Boeing MD-11 accident (Flight International, 8-14 April) reminded me of a flight I made in 1997 from Dublin to Brussels.

Just after take-off we had smoke in the cockpit and the captain ordered the flight engineer to initiate fuel dumping at 1,500ft (460m) and we were back on the ground within 6min. Cargo and smoke detectors failed to detect the source, but a few weeks later it was found to be from an autopilot servo under the flying officer's yoke.

This told me that there is no smoke without fire, sparks or heat, all of which in isolation or combination are detrimental to continued flight and time wasted in trying to locate and isolate its source without immediate descent and diversion diminishes the time remaining to make it successfully.

Some time before the Swiss Air incident, a FedEx McDonnell Douglas DC-10 had a sequential illumination of smoke detector lights. The captain initiated an immediate descent and diversion to Buffalo, New York airport, and landed safely without reference to charts. After evacuation, the aircraft burned out.

On some aircraft the general procedure is oxygen, goggles, communicate, descend on/off track and divert - without hesitation.

Hindsight is wonderful, but had the Swiss Air crew initiated an immediate "Mayday" descent and diversion with the co-pilot completing emergency/abnormal procedures and fuel jettison, then it is possible a non-fatal landing in Halifax could have been made.

David Connolly Brussels, Belgium

Source: Flight International