What happened
On 22 April 2006, a Bombardier CL600-2B19 CRJ200, registration D-ACHA, was operating a scheduled passenger flight from London Heathrow to Dusseldorf. Shortly after departing from London, the crew received a 'SMOKE CARGO' alert via the Engine Indicating and Crew Alerting System (EICAS).
In response to the warning, the crew executed emergency procedures, declared an emergency, and initiated a return to London Heathrow. Upon landing, the aircraft stopped at the first available runway exit where the Airport Fire and Rescue Services (AFRS) were already positioned. Following an inspection by the rescue teams, no evidence of smoke or fire was detected. The crew subsequently conducted a search of the cargo hold, which also yielded no signs of fire. The aircraft was towed to a parking stand, and the 50 passengers and 4 crew members disembarked without further incident.
The investigation
The AAIB examined the circumstances surrounding the alert and identified that the warning was false. The investigation noted that this specific aircraft had previously been upgraded with a new smoke detector design intended to prevent false triggers. However, the investigation established that the warning was likely triggered by external factors such as dust, condensation, or electromagnetic interference.
Evidence was also reviewed regarding previous similar events within the operator's fleet, including a prior incident involving aircraft D-ACHH. The investigation highlighted that despite recent modifications to the cargo smoke detectors and fire bottles across the operator's CRJ100/200 fleet, the issue of spurious warnings had persisted.