Date of release: Tuesday, April 11, 2017
Research by the University of Greenwich has explained for the first time why 55 people lost their lives when fire swept through British Airtours flight 28M.
Professor Ed Galea, Group Director, says: "Our analysis has significant implications for aviation safety today. We found the number of fatalities could have been reduced by 87 per cent had the forward right exit not malfunctioned, and by 36 per cent had the right over-wing exit been opened without delay."
The group coupled fire and evacuation computer simulations to reconstruct what happened from the moment engine failure damaged fuel lines and a fuel tank, resulting in a large external fire. Pilots aborted take-off and came off the runway at Manchester Airport, unfortunately turning the aircraft into the wind which allowed smoke and flames to engulf it.
Professor Galea, who began his career in fire safety engineering in 1985 researching the same incident, has developed world-leading modelling software in both fire dynamics and human behaviour in evacuation scenarios with his team at FSEG. Thirty years on, he has been able to couple the two and solve the mysteries surrounding the fire.
He says: "This was a pivotal incident that changed the course of aviation safety around the world. It was instrumental in improving aircraft evacuation procedures, cabin layout, cabin interior materials and aircraft operations. But no-one knew how significant the delays in opening the doors were, how wind speed and direction affected the fire, or what the potential benefit offered by modern cabin materials would have been."
A key finding of the report is that a cabin crew member must be available at each floor-level exit who can open it within seconds. In the Manchester Airport incident, there was effectively only one crew member available to open both front doors, one of which had malfunctioned. A second crew member, also located in the forward position beside the exits, was engaged in holding back the passengers allowing her colleague to eventually open both exits.
In the event it took 25 seconds to open one and 70 seconds to open the second, much longer than the normal time in aviation industry evacuation certification trials of under ten seconds.
The peer-reviewed journal paper also says it is essential that passengers seated by the manually-operated overwing exits know how to open them. In the Manchester incident the passenger next to the wing door struggled to get it open; eventually another passenger leaned over and opened it after 45 seconds. In industry standard certification trials, these exits are normally opened by passengers within 12 seconds.
The FSEG simulations demonstrated that these few seconds' delay in opening the three viable exits directly resulted in the large loss of life. Had the exits opened in the time achieved in certification trials it is likely that all the passengers would have been able to safely evacuate.
Professor Galea says: "The Manchester incident demonstrates that during an aircraft fire, literally every second can make the difference between life and death. This is why it is essential to have well trained cabin crew at each exit, why passengers seated beside overwing exits must be capable of opening them in seconds, and why passengers should not waste time retrieving luggage from overhead bins during an emergency evacuation."
The FSEG simulations also demonstrated that it would only take a relatively light wind of 1.5 m/s (metres per second) to cause the external ﬁre plume to lean onto the fuselage as it did that day, with the capability to burn through the fuselages.
On the day of the incident, the wind speed, while low at around 3.0 m/s, was much greater than the critical wind speed. The report says the position of the aircraft in relation to wind direction is critically important: "Aircrew should be advised to position the aircraft most beneﬁcially against the wind in the event of a ground ﬁre."
In the Manchester incident, fire burned through the fuselage in about 75 seconds. Simulations show that a delay of only a further 50 seconds could, potentially, have allowed all the passengers to escape. In 1985, the insulation materials typically used inside the cabin's aluminium skin had a "burn-through resistance" of around 52-96 seconds.
New generation insulation materials have a signiﬁcantly improved resistance with burn-through times of between four and eight minutes. The research shows that the use of such insulation would have saved the Manchester victims.
The paper describes how FSEG has developed two key pieces of software: SMARTFIRE, which uses advanced CFD (Computational Fluid Dynamics) fire simulation with pool fire and combustion models, and airEXODUS, an advanced evacuation simulation tool. It was the coupling of these two programmes which enabled the analysis of the Manchester Airport fire.
The full citation for the paper is: Galea E.R., Wang Z., and Jia F., NUMERICAL INVESTIGATION OF THE FATAL 1985 MANCHESTER AIRPORT B737 FIRE, Aeronautical Journal, Vol 121, Number 1237, pp 287-319, 2017.
Picture: Professor Ed Galea.