What happened
On 6 April 2005, a Shorts SD3-60-100, registration EI-SMB, was operating a night-time Royal Mail cargo service from Edinburgh to Kinloss. Shortly after departing from runway 12, while climbing through FL55, the commander detected an unusual odour. A visual check through the cockpit door revealed a white vapour emerging from beneath the cargo netting and spreading throughout the hold.
Believing the vapour to be smoke, the pilot notified Air Traffic Control of an onboard fire and requested an immediate return to Edinburgh. During the radar-vectored approach, the crew observed that the cargo area had become filled with a dense white smoke. In accordance with safety procedures, the crew completed the cargo fire checklist and prepared oxygen masks and goggles. As the aircraft stabilised for a visual approach, the smoke appeared to have dissipated. The aircraft landed safely, and the crew evacuated the aircraft as the Airport Fire Service arrived on the runway.
The investigation
The investigation focused on identifying the source of the smoke and the nature of the cargo. The Airport Fire Service utilised a thermal imaging camera to inspect the hold, but the scan showed no evidence of heat or active fire. All cargo packages remained intact and undamaged.
Because no shipper's declaration was available to the crew, the specific contents of the packages could not be immediately identified; however, the investigation confirmed that no dangerous goods were being transported. Subsequent inspections of the aircraft during cargo offloading revealed no mechanical or structural issues capable of producing such vapour. The cargo was transported to Inverness, where Royal Mail personnel conducted an external inspection of all packages, finding no leaks or damage.
Findings
- The crew's belief that a fire was occurring was based on the visual presence of white vapour and an unusual smell.
- The source of the smoke or vapour could not be identified due to the lack of evidence of leakage or damage to the cargo packaging.