Incident
On 18 November 2000, shortly after takeoff from London Heathrow Airport, cabin crew on board a Boeing 767-300, registration N657UA, noticed smoke emanating from the right-hand business class toilet. The aircraft was operating a public transport (passenger) flight with 12 crew and 97 passengers on board.
Response
The cabin crew discharged a Halon fire extinguisher into the toilet waste disposal shoot and informed the flight crew of a possible fire. The commander declared an emergency to air traffic control and requested that emergency services be on standby for the aircraft's return to Heathrow. The aircraft landed back at Heathrow without further incident, and the smoke ceased. Airport Fire Service personnel boarded the aircraft and inspected the toilet, but found no evidence of a fire.
Investigation
The operator's maintenance organization later determined that the toilet's water heater had developed a short-circuit, which caused overheating and produced the smoke observed by the cabin crew. The water heater was subsequently replaced. No injuries were reported among the crew or passengers. The commander held an Airline Transport Pilot's Licence, was 42 years old, and had 10,000 hours of flying experience, including 3,000 hours on type.