American Airlines Boeing 767-300 Diverts Following Burning Odor

An American Airlines Boeing 767-300 has been diverted following the presence of a burning odor in the cabin, as well as in the cockpit. The incident took place on flight AA-734 after departing Philadelphia on September 25th. The flight was en route to Manchester (UK) when crew made the decision to divert to St. Johns in Newfoundland. The aircraft landed safely with its 170 passengers and crew on board around four and a half hours after taking off. Simple Flying has investigated the incident.

An American Airlines Boeing 767-300 had to divert after the presence of a burning odor in the cabin and cockpit. Photo: Grant Wickes via Flickr

American Airlines flight AA-734

The aircraft in question departed from Philadelphia International Airport on the 25th of September, on a scheduled flight to Manchester Airport in the United Kingdom. The airline was using one of its 767-300 fleet with the registration N397AN.

As reported by the Aviation Herald, a smell became apparent in the cockpit and cabin area whilst the aircraft was passing by the Canadian mainland. When the 767 was around 210 nautical miles east-southeast of St. Johns in Newfoundland, the crew made the decision to divert the aircraft as a precaution and to further investigate the matter safely on the ground.

American Airlines 767 diversion
The path of the diverted flight. Image: FlightRadar24

All of the 170 people on board were safe when the flight touched down at St. Johns International airport, just over four and a half hours after take-off. The aircraft remained on the ground in St. Johns for several hours before being ferried back to Philadelphia empty.

The passengers, unfortunately, had a long delay as a result, waiting for around 15 hours at St. Johns for a replacement aircraft. Another Boeing 767, registration N348AN, finally completed the flight, arriving at Manchester Airport at just before 23:00 local time on the 26th September, almost a full 24 hours after taking off from Philly.

Potential cause of an SBO-event

The presence of a burning odor in the cabin and/or cockpit is classed as an SBO (Smoke and Burning Odor) event on an aircraft. For the most part, SBO events in the aircraft cabin are resolved without affecting a safe onwards flight, a safe landing, or egress.

This does not, however, mean that such events aren’t the result of serious operational issues. Boeing has investigated a number of SBO events on a series of its aircraft, including the 767, in order to better equip crews to safely manage the situation.

Bearing in mind that not all incidents are referred back to Boeing, these are the five likeliest causes that Boeing have identified as leading to SBO-events:

  • The recirculation fan
  • Engine oil over-servicing
  • The equipment cooling fan
  • An air supply contamination leading to an engine fault
  • The window anti-icing circuit
American Airlines Boeing 767-300 Diverts Following Burning Odor
The recirculation fan was the leading cause of SBO events on Boeing 757 aircraft, between 2004 and 2008. Photo: Benjamin van Waart via Flickr

In most cases, these have led to diversions and minimal interruptions. The recirculation fan accounted for 21 incidents between 2004 and 2008, with most of the flights requiring a diversion en route. American Airlines have been contacted to comment on the potential cause of the SBO.

Update: American Airlines responded to the inquiry by Simple Flying, and has released the following information:

“A replacement flight, crew and a Tech Ops team were sent to YYT to continue the fight to Manchester, and troubleshoot the odor. The replacement aircraft continued with the passengers to Manchester. The issue was isolated to some burnt food in the first class oven.

“The original aircraft departed St. John as a ferry flight on Sept. 27 at 9:14 a.m. local time, landing in PHL at 10: 42 a.m. The plane was put back into service that same day.”

Recent American Airlines fume incident

In July of this year, another American Airlines flight from Philadelphia to London had to divert to Boston due to a fume incident. This time it was on one of the carrier’s Airbus A330’s, and the flight was interrupted due to an “old-socks smell” picked up by passengers and crew. In this instance, although all on board were safe, 10 crew members were taken to hospital after feeling ill.