Kegworth air disaster
Encyclopedia
The Kegworth Air Disaster occurred on 8 January 1989, when British Midland
Flight 92, a Boeing 737–400
, crashed onto the embankment of the M1 motorway
near Kegworth
, Leicestershire, in England. The aircraft was attempting to conduct an emergency landing
at East Midlands Airport. Of the 126 people aboard, 47 died and 74, including seven members of the flight crew, sustained serious injuries.
G-OBME, on a scheduled flight from London Heathrow Airport
to Belfast
, Northern Ireland
, having already flown from Heathrow to Belfast and back that day. After taking off from Heathrow at 7:52 pm, Flight 092 was climbing through 28,300 feet to reach its cruising altitude of 35,000 feet when a blade detached from the fan of the port engine. While the pilots did not know the source of the problem, a pounding noise was suddenly heard, accompanied by severe vibration
s. In addition, smoke poured into the cabin through the ventilation system and a smell of burning entered the plane. Several passengers sitting near the rear of the plane noticed smoke and sparks coming from the left engine.
The flight was diverted to nearby East Midlands Airport at the suggestion of British Midland Airways Operations.
After the initial blade fracture, Captain Kevin Hunt had disengaged the plane's autopilot
. When Hunt asked First Officer David McClelland which engine was malfunctioning, McClelland replied: 'It's the left one. No, the right one'. In previous versions of the 737, the left air conditioning pack, fed with compressor bleed air from the left (number 1) engine, supplied air to the flight deck, while the right air conditioning pack, fed from the right (number 2) engine supplied air to the cabin. On the 737-400 this division of air is blurred; the left pack feeds the flight deck but also feeds the aft cabin zone, while the right feeds the forward cabin. The pilots had been used to the older version of the aircraft and did not realise that this aircraft (which had only been flown by British Midland for 520 hours over a two-month period) was different. The smoke in the cabin led them to assume the fault was in the right engine; this led them to shut down the working right engine instead of the malfunctioning left engine. They had no way of visually checking the engines from the cockpit, and the cabin crew did not inform them that smoke and flames had been seen from the left engine.
When the pilots shut down the right engine, they could no longer smell the smoke, which led them to believe that they had correctly dealt with the problem. As it turned out, this was simply a coincidence: when the autothrottle
was disengaged to shut down the right engine, the fuel flow to the left engine was reduced, and the excess fuel which had been igniting in the jet exhaust disappeared; therefore, the ongoing damage was reduced, the smoke smell ceased, and the vibration reduced, although it would still have been visible on cockpit instruments. The pilots, however, did not consult the vibration detectors because these instruments, on previous planes they had flown, were notoriously unreliable.
During the final approach to the East Midlands Airport, more fuel was pumped into the damaged engine to maintain speed, which caused it to cease operating entirely and burst into flames. The flight crew attempted to restart the right engine by windmilling, using the air flowing through the engine to rotate the turbine blades and start the engine, but the aircraft was by now flying only at 185 km/h, too slow for this. Just before crossing the M1 motorway
, the tail slammed onto the ground and the aircraft bounced back into the air and over the motorway, knocking down trees and a lamp-post before crashing on the opposite embankment and breaking into three sections approximately 475m (1/4 mile) short from the active runway
's paved surface and approximately 630m (1/3 mile) from its threshold.
. Four members of the British Army serving in Northern Ireland were among those killed in the crash.
for cabin air conditioning was taken from the right engine. However, starting with the Boeing 737–400 variant, Boeing redesigned the system to use bleed air from both engines. Several cabin staff and passengers noticed that the left engine had a stream of unburnt fuel igniting in the jet exhaust, but this information was not passed to the pilots because cabin staff assumed the pilots were aware that the left engine was malfunctioning.
After disabling the autothrottle, the left engine flames stopped as they weren't being pumped fuel.
It was a coincidence that the smell of smoke disappeared when the autothrottle was disengaged and the right engine shut down. In the event of a malfunction pilots are trained to check all meters and review all decisions, and Captain Kevin Hunt proceeded to do so. Whilst he was conducting the review, he was interrupted by a transmission from East Midlands Airport informing him he could descend further to 12000 feet (3,657.6 m) in preparation for the diverted landing. He did not resume the review after the transmission ended, and instead commenced descent. The vibration indicators were smaller than on the previous versions of the 737 in which the pilots had the majority of their experience.
The dial on the two vibration gauges (one for each engine) were no bigger than a 50 pence piece
and the LED needle went around the outside of the dial as opposed to the inside of the dial as in the previous 737 series aircraft. The pilots had received no simulator training on the new model as no simulator for the 737-400 existed in the UK at that time. At the time vibration indicators were known for being unreliable (and in fact normally ignored by pilots) but unknown to the pilots this was one of the first aircraft at the time to have a very accurate vibration readout.
-400s (since G-OBME had crashed) were grounded and the engines modified. Following the crash, it is now mandatory to test all newly designed and significantly redesigned turbofan engines under representative flight conditions.
This unnoticed vibration created excessive metal fatigue
in the fan blades, and on G-OBME this caused one of the fan blades to break off. This damaged the engine terminally and also upset its delicate balance, causing a reduction in power and an increase in vibration. The autothrottle attempted to compensate for this by increasing the fuel flow to the engine, however the damaged engine was unable to burn all the additional fuel, with much of it igniting in the exhaust flow, creating a large trail of flame behind the engine.
Evaluation of the injuries sustained led to considerable improvements in aircraft safety and emergency instructions for passengers. These were derived from a research programme funded by the CAA and carried out by teams from the University of Nottingham and Hawtal Whiting Structures (a consultancy company). The study between medical staff and engineers used analytical "occupant kinematics" techniques to assess the effectiveness of the brace position
. A new notice to operators revising the brace position was issued in October 1993.
There is a memorial to "those who died, those who were injured and those who took part in the rescue operation", in the village cemetery in nearby Kegworth
, together with a garden made using soil
from the crash site.
Captain Hunt and First Officer McClelland were seriously injured in the crash, and were later dismissed following the criticisms of their actions in the AAIB
report.
, called "Motorway Plane Crash".
It was also featured in the 2011 Discovery Channel
documentary 'Aircrash Confidential'
.
Bmi (airline)
British Midland Airways Limited , is an airline based at Donington Hall in Castle Donington in the United Kingdom, close to East Midlands Airport, and a fully owned subsidiary of Lufthansa...
Flight 92, a Boeing 737–400
Boeing 737 Classic
The Boeing 737 Classic is the name given to the -300/-400/-500 series of the Boeing 737 following the introduction of the -600/-700/-800/-900 series. They are short- to medium- range, narrow-body jet airliners produced by Boeing Commercial Airplanes. The Classic series was introduced as the 'new...
, crashed onto the embankment of the M1 motorway
M1 motorway
The M1 is a north–south motorway in England primarily connecting London to Leeds, where it joins the A1 near Aberford. While the M1 is considered to be the first inter-urban motorway to be completed in the United Kingdom, the first road to be built to motorway standard in the country was the...
near Kegworth
Kegworth
Kegworth is a large village and civil parish in Leicestershire, England....
, Leicestershire, in England. The aircraft was attempting to conduct an emergency landing
Emergency landing
An emergency landing is a landing made by an aircraft in response to a crisis which either interferes with the operation of the aircraft or involves sudden medical emergencies necessitating diversion to the nearest airport.-Types of emergency landings:...
at East Midlands Airport. Of the 126 people aboard, 47 died and 74, including seven members of the flight crew, sustained serious injuries.
History
The aircraft was a British Midland 737-400, aircraft registrationAircraft registration
An aircraft registration is a unique alphanumeric string that identifies a civil aircraft, in similar fashion to a licence plate on an automobile...
G-OBME, on a scheduled flight from London Heathrow Airport
London Heathrow Airport
London Heathrow Airport or Heathrow , in the London Borough of Hillingdon, is the busiest airport in the United Kingdom and the third busiest airport in the world in terms of total passenger traffic, handling more international passengers than any other airport around the globe...
to Belfast
Belfast
Belfast is the capital of and largest city in Northern Ireland. By population, it is the 14th biggest city in the United Kingdom and second biggest on the island of Ireland . It is the seat of the devolved government and legislative Northern Ireland Assembly...
, Northern Ireland
Northern Ireland
Northern Ireland is one of the four countries of the United Kingdom. Situated in the north-east of the island of Ireland, it shares a border with the Republic of Ireland to the south and west...
, having already flown from Heathrow to Belfast and back that day. After taking off from Heathrow at 7:52 pm, Flight 092 was climbing through 28,300 feet to reach its cruising altitude of 35,000 feet when a blade detached from the fan of the port engine. While the pilots did not know the source of the problem, a pounding noise was suddenly heard, accompanied by severe vibration
Vibration
Vibration refers to mechanical oscillations about an equilibrium point. The oscillations may be periodic such as the motion of a pendulum or random such as the movement of a tire on a gravel road.Vibration is occasionally "desirable"...
s. In addition, smoke poured into the cabin through the ventilation system and a smell of burning entered the plane. Several passengers sitting near the rear of the plane noticed smoke and sparks coming from the left engine.
The flight was diverted to nearby East Midlands Airport at the suggestion of British Midland Airways Operations.
After the initial blade fracture, Captain Kevin Hunt had disengaged the plane's autopilot
Autopilot
An autopilot is a mechanical, electrical, or hydraulic system used to guide a vehicle without assistance from a human being. An autopilot can refer specifically to aircraft, self-steering gear for boats, or auto guidance of space craft and missiles...
. When Hunt asked First Officer David McClelland which engine was malfunctioning, McClelland replied: 'It's the left one. No, the right one'. In previous versions of the 737, the left air conditioning pack, fed with compressor bleed air from the left (number 1) engine, supplied air to the flight deck, while the right air conditioning pack, fed from the right (number 2) engine supplied air to the cabin. On the 737-400 this division of air is blurred; the left pack feeds the flight deck but also feeds the aft cabin zone, while the right feeds the forward cabin. The pilots had been used to the older version of the aircraft and did not realise that this aircraft (which had only been flown by British Midland for 520 hours over a two-month period) was different. The smoke in the cabin led them to assume the fault was in the right engine; this led them to shut down the working right engine instead of the malfunctioning left engine. They had no way of visually checking the engines from the cockpit, and the cabin crew did not inform them that smoke and flames had been seen from the left engine.
When the pilots shut down the right engine, they could no longer smell the smoke, which led them to believe that they had correctly dealt with the problem. As it turned out, this was simply a coincidence: when the autothrottle
Autothrottle
An autothrottle allows a pilot to control the power setting of an aircraft's engines by specifying a desired flight characteristic, rather than manually controlling fuel flow...
was disengaged to shut down the right engine, the fuel flow to the left engine was reduced, and the excess fuel which had been igniting in the jet exhaust disappeared; therefore, the ongoing damage was reduced, the smoke smell ceased, and the vibration reduced, although it would still have been visible on cockpit instruments. The pilots, however, did not consult the vibration detectors because these instruments, on previous planes they had flown, were notoriously unreliable.
During the final approach to the East Midlands Airport, more fuel was pumped into the damaged engine to maintain speed, which caused it to cease operating entirely and burst into flames. The flight crew attempted to restart the right engine by windmilling, using the air flowing through the engine to rotate the turbine blades and start the engine, but the aircraft was by now flying only at 185 km/h, too slow for this. Just before crossing the M1 motorway
M1 motorway
The M1 is a north–south motorway in England primarily connecting London to Leeds, where it joins the A1 near Aberford. While the M1 is considered to be the first inter-urban motorway to be completed in the United Kingdom, the first road to be built to motorway standard in the country was the...
, the tail slammed onto the ground and the aircraft bounced back into the air and over the motorway, knocking down trees and a lamp-post before crashing on the opposite embankment and breaking into three sections approximately 475m (1/4 mile) short from the active runway
Runway
According to ICAO a runway is a "defined rectangular area on a land aerodrome prepared for the landing and take-off of aircraft." Runways may be a man-made surface or a natural surface .- Orientation and dimensions :Runways are named by a number between 01 and 36, which is generally one tenth...
's paved surface and approximately 630m (1/3 mile) from its threshold.
Casualties
Of the 118 passengers on board, thirty-nine were killed in the crash and eight died later, for a total of forty-seven fatalities. All eight members of the flight crew survived the accident. Of the 79 survivors, 74 suffered serious injuries and five suffered minor injuries. No-one on the motorway was injured, and all vehicles in the vicinity of the disaster were undamaged. The first person to arrive at the scene to render aid was a motorist who subsequently received damages for post-traumatic stress disorderPost-traumatic stress disorder
Posttraumaticstress disorder is a severe anxiety disorder that can develop after exposure to any event that results in psychological trauma. This event may involve the threat of death to oneself or to someone else, or to one's own or someone else's physical, sexual, or psychological integrity,...
. Four members of the British Army serving in Northern Ireland were among those killed in the crash.
Shutting down the wrong engine
The Captain, Kevin Hunt, believed the right engine was malfunctioning due to the smell of smoke in the cabin because in previous Boeing 737 variants bleed airBleed air
Bleed air in gas turbine engines is compressed air taken from within the engine, after the compressor stage and before the fuel is injected in the burners. While in theory bleed air could be drawn in any gas turbine engine, its usage is generally restricted to jet engines used in aircraft...
for cabin air conditioning was taken from the right engine. However, starting with the Boeing 737–400 variant, Boeing redesigned the system to use bleed air from both engines. Several cabin staff and passengers noticed that the left engine had a stream of unburnt fuel igniting in the jet exhaust, but this information was not passed to the pilots because cabin staff assumed the pilots were aware that the left engine was malfunctioning.
After disabling the autothrottle, the left engine flames stopped as they weren't being pumped fuel.
It was a coincidence that the smell of smoke disappeared when the autothrottle was disengaged and the right engine shut down. In the event of a malfunction pilots are trained to check all meters and review all decisions, and Captain Kevin Hunt proceeded to do so. Whilst he was conducting the review, he was interrupted by a transmission from East Midlands Airport informing him he could descend further to 12000 feet (3,657.6 m) in preparation for the diverted landing. He did not resume the review after the transmission ended, and instead commenced descent. The vibration indicators were smaller than on the previous versions of the 737 in which the pilots had the majority of their experience.
The dial on the two vibration gauges (one for each engine) were no bigger than a 50 pence piece
British Fifty Pence coin
The British decimal fifty pence coin – often pronounced "fifty pee" – was issued on 14 October 1969 in the run-up to decimalisation to replace the ten shilling note...
and the LED needle went around the outside of the dial as opposed to the inside of the dial as in the previous 737 series aircraft. The pilots had received no simulator training on the new model as no simulator for the 737-400 existed in the UK at that time. At the time vibration indicators were known for being unreliable (and in fact normally ignored by pilots) but unknown to the pilots this was one of the first aircraft at the time to have a very accurate vibration readout.
Engine malfunction
Analysis of the engine from the crash determined that the fan blades (LP Stage 1 compressor) of the uprated CFM56 engine used on the 737-400 were subject to abnormal amounts of vibration when operating at high power settings above 25000 feet (7,620 m). As it was an upgrade to an existing engine, in-flight testing was not mandatory, and the engine had only been tested in the laboratory. Upon this discovery all 99 Boeing 737Boeing 737
The Boeing 737 is a short- to medium-range, twin-engine narrow-body jet airliner. Originally developed as a shorter, lower-cost twin-engine airliner derived from Boeing's 707 and 727, the 737 has developed into a family of nine passenger models with a capacity of 85 to 215 passengers...
-400s (since G-OBME had crashed) were grounded and the engines modified. Following the crash, it is now mandatory to test all newly designed and significantly redesigned turbofan engines under representative flight conditions.
This unnoticed vibration created excessive metal fatigue
Metal Fatigue
Metal Fatigue , is a futuristic science fiction, real-time strategy computer game developed by Zono Incorporated and published by Psygnosis and TalonSoft .-Plot:...
in the fan blades, and on G-OBME this caused one of the fan blades to break off. This damaged the engine terminally and also upset its delicate balance, causing a reduction in power and an increase in vibration. The autothrottle attempted to compensate for this by increasing the fuel flow to the engine, however the damaged engine was unable to burn all the additional fuel, with much of it igniting in the exhaust flow, creating a large trail of flame behind the engine.
Aftermath
The official report into the disaster made 31 safety recommendations.Evaluation of the injuries sustained led to considerable improvements in aircraft safety and emergency instructions for passengers. These were derived from a research programme funded by the CAA and carried out by teams from the University of Nottingham and Hawtal Whiting Structures (a consultancy company). The study between medical staff and engineers used analytical "occupant kinematics" techniques to assess the effectiveness of the brace position
Brace position
Bracing or crash position is an instruction that can be given to prepare for a crash, such as on an aircraft, the instruction to brace for impact is often given if the aircraft must make an emergency landing over land or water....
. A new notice to operators revising the brace position was issued in October 1993.
There is a memorial to "those who died, those who were injured and those who took part in the rescue operation", in the village cemetery in nearby Kegworth
Kegworth
Kegworth is a large village and civil parish in Leicestershire, England....
, together with a garden made using soil
Soil
Soil is a natural body consisting of layers of mineral constituents of variable thicknesses, which differ from the parent materials in their morphological, physical, chemical, and mineralogical characteristics...
from the crash site.
Captain Hunt and First Officer McClelland were seriously injured in the crash, and were later dismissed following the criticisms of their actions in the AAIB
Air Accidents Investigation Branch
The Air Accidents Investigation Branch investigates air accidents in the United Kingdom. It is a branch of the Department for Transport and is based on the grounds of Farnborough Airport near Aldershot, Rushmoor, Hampshire.-History:...
report.
Media
British Midland Flight 092 was featured in an episode of Seconds From DisasterSeconds From Disaster
-By original broadcast date:National Geographic Channel has broadcast many episodes under multiple titles. The title currently or most recently listed on the NGC Calendar is shown first...
, called "Motorway Plane Crash".
It was also featured in the 2011 Discovery Channel
Discovery Channel
Discovery Channel is an American satellite and cable specialty channel , founded by John Hendricks and distributed by Discovery Communications. It is a publicly traded company run by CEO David Zaslav...
documentary 'Aircrash Confidential'
Aircrash Confidential
Aircrash Confidential or Air Crash Confidential was a programme produced by WMR Productions and IMG Entertainment investigating air-disasters from around the world. Aircrash Confidential airs on Discovery Channel UK on a weekly-nightly basis and it also airs in Australia on Discovery Australia...
.
See also
External links
- The official AAIB report, Air Accidents Investigation BranchAir Accidents Investigation BranchThe Air Accidents Investigation Branch investigates air accidents in the United Kingdom. It is a branch of the Department for Transport and is based on the grounds of Farnborough Airport near Aldershot, Rushmoor, Hampshire.-History:...
- aaib.gov.uk- PDF version (Archive)
- Appendices (Archive)
- Text version of the report at the University of Bielefeld
- BBC 10th anniversary page about the crash
- BBC 'On This Day' page about the crash
- BBC story about Graham Pearson, who received damages in 1998 after witnessing the crash and helping the survivors
- Derby Telegraph articles and photographs about the crash, thisisderbyshire.co.uk
- Kegworth disaster, kegworthvillage.com
- Pre-crash and crash pictures of the aircraft from Airliners.netAirliners.netAirliners.net is an aviation website founded by Johan Lundgren, Sweden, in 1997, evolving from his previous Pictures of Modern Airliners site started in 1994...