Are you worried about flying or just curious and wondering why planes crash?
Thankfully the chances of a plane crash are extremely low – the National Transportation Safety Board recon believe the chances of dying in a commercial plane crash are 1 in 3.7billion (flyfright.com).
What are the main causes of plane crashes?
Fatal plane crashes are seldom down to one reason alone but due to multiple factors that unfortunately all come together (Reasons model/ swiss cheese model) to cause an accident or plane crash.
Harro Ranter, chief executive officer of the Aviation Safety Network, said. “In most accidents, several factors are involved,”.
“In accident investigation, there is no such thing as a simple cause like ‘pilot error.’ There is always more involved.”.
According to the statistics from the website planecrashinfo.com (which examined accidents from 1/1/1950 to 6/30/2019 looking at aircraft carrying at least 19 passengers with at least 2 fatalities, excluding military, helicopters and private aircraft) – the main causes of aircraft crashes were
- Pilot Error
- Mechanical Failure
- Weather
- Sabotage
- Other forms of human error
Simon Bennet (Director of the Civil Safety and Security Unit (CSSU), University of Leicester) also listed these causes in the article The five most common reasons for airliner disasters
Pilot Error
As aircraft have become more advanced, reliability increasing and more automation being available to pilots, pilot error is increasingly the largest contributor the plane crashes.
Analysis of 1085 accidents by planecrashinfo.com between 1950 and 2019 attributes pilot error to around 49% of all plane crashes.
In modern aviation, pilots try to prevent mistakes by themselves through practising threat and error management. This is the open recognition that pilots are human beings and as such, are likely to make mistakes.
Standard operating procedures
In many plane crashes, lack of adherence to following standard operating procedures or having weak standard operating procedures has led to plane crashes.
If we look at the fatal Air France Concorde crash on 25th July 2010, the BEA investigation found that a metallic strip from a DC-10 aircraft that took off 5 mins ahead of Concorde, caused Concordes fuel tanks to rupture.
The crash report and investigation found the metal strip caused a tyre burst during the high-speed part of the take-off roll, which in turn caused a fire as a result of tyre debris rupturing one of the fuel tanks, which led to the Concorde crashing.
100 passengers, 9 crew and 4 other people died in the Air France Concorde crash.
The BEA report found that the metallic strip on the DC-10 had neither been manufactured nor installed in accordance with the procedures as defined by the manufacturer.
This is an extreme case where not following procedures led to the Concorde crash and a significant loss of life.
Each airline and aircraft manufacture will have standard operating procedures. These procedures govern how the aircraft is maintained and flown from opening the door right the way through to completing the landing.
Standard operating procedures prevent crashes by having a framework to complete vital actions in the air and on the ground and checking those items have been completed.
For maintenance actions, following the manufacturer’s procedures and using approved parts is key to stopping plane crashed from happening.
Following checklists
A Spanair MD82 crashed on takeoff at Madrid-Barajas Airport killing 154 on 20th August 2008. Included were all 6 crew members and 18 seriously injured.
The final report by CAIIAC, report A-032/2008 found that some items on the ‘After Start’ checklist were omitted leading to the flaps and slats not being selected and their positions not being verified during the take-off briefing.
From the report, what didn’t help in the Spanair MD82 crash was that the take-off warning system (TOWS) did not issue any warnings during the takeoff run regarding the improper selection of slats and flaps for take off.
To support standard operating procedures, checklists are an additional barrier to prevent making mistakes. Pilots in the flight deck will complete checklists using the READ – LOOK – LISTEN philosophy.
One of the pilot calls out the checklist item e.g. Landing Gear, the other pilot will LOOK to check its position, and then respond verbally to confirm the item is where it should be e.g. DOWN.
Practising non normal manouevers (6 monthly checks)
With pilot error being one of the largest contributors to plane crashes, it is important for crews to practice emergency scenarios regularly to minimise the chances of mistakes being made in real-life emergencies.
Most professional pilots have 6 monthly recurrent simulator sessions. These sessions allow procedures for items such as engine failure, catastrophic fires or even rapid cabin depressurisation to be practised.
A Boeing 737-400 crashed near Kegworth in Leicestershire, 8th January 1989. 47 passengers were killed with 74 seriously injured.
The Air Accident Investigations Branch (AAIB) report found that while the decision to divert to East Midlands Airport was correct the flight crew reacted to the initial engine problem prematurely and in a way that was contrary to their training.
From the AAIB report, The cause of the plane crash was that the operating crew shut down the No2 engine, after a fan blade had fractured in the No1 engine.
This engine subsequently suffered a major thrust loss due to secondary fan damage after power had been increased during the final approach to land.
Plane crashes because of poor crew resource management
There have been many crashes where one crew or parties involved in an operation knew they were about to crash or were in a dangerous situation but did nothing about it but did not advocate their position strongly enough until it was too late.
The root cause of the worst air accident in modern times involving a collision between a KLM 747 and Pan Am 747 in Tenerife is as follows (Source- Netherlands Aviation Safety Board – Final report investigating the collision between KLM Flight 4805 and Pan Am flight 1736):
The KLM aircraft has taken off without takeoff clearance, in the absolute conviction that this clearance had been obtained, which was the result of a misunderstanding between the tower and the KLM aircraft.
This misunderstanding has arisen from the mutual use of terminology which, however, gave rise to misrepresentation. In combination with a number of other coinciding circumstances, the premature take off of the KLM aircraft resulted in a collision with the Pan Am aircraft, because the latter was still on the runway since it had missed the correct intersection.
The flight engineering onboard KLM had doubts that the takeoff clearance had been received but was not heard by the KLM pilots or at least they didn’t react.
At the same time, the Pan Am crew became alarmed and tried to alert the tower they were still on the runway, but their transmission was blocked. The tower was not more forceful in getting confirmation from KLM that they were not cleared for take-off.
This accident may have been averted if either the KLM flight engineer, Pan Am crew or air traffic had been more assertive in their communications.
Poor visibility, delays experienced and crews getting delayed during that day all added to the circumstances that led to the accident.
Pilot judgement
Poor pilot judgement has been one of the factors in many plane crashes. Excellent pilot judgement has also significantly improved the outcome of other plane crashes that could have been a lot worse.
The NTSB report into the Loss of Thrust in Both Engines After Encountering a Flock of Birds and Subsequent Ditching on the Hudson River US Airways Flight 1549 Airbus A320‐214, New York, New Jersey January 15, 2009, shows how excellent airmanship saved hundreds of lives that day.
The NTSB report states that contributing to the survivability of the accident was
(1) the decision-making of the flight crewmembers and their crew resource management during the accident sequence;
(2) the fortuitous use of an airplane that was equipped for an extended overwater flight, including the availability of the forward slide/rafts, even though it was not required to be so equipped;
(3) the performance of the cabin crewmembers while expediting the evacuation of the airplane; and
(4) the proximity of the emergency responders to the accident site and their immediate and appropriate response to the accident.
With the loss of thrust on both engines happening so close to the ground on US Airways flight 1549 (approximately 2800ft AGL), they had very little time to deal with the problem. The flight crew had to improvise and work together – which they did extremely well leading to a successful ditching in the Hudson.
From the report, the flight crew were not able to initiate part 2 of the Engine Dual Failure checklist (not enough time), which contained airspeed guidance for pilots to follow if an engine restart is considered impossible and a ditching is anticipated.
The captain from interviews flew the recommended speeds and his flap selection (flap 2) was excellent to allow as safe as possible ditching.
There were no fatalities and it is all the more remarkable that only 5 people were seriously injured given the aircraft ditched in the Hudson River.
Mechanical failure
Mechanical failure accounts for around 20% of the causes of fatal accidents (Source: planecrashinfo.com).
On 19th July 1989, a United Airlines DC-10 (flight 232) suffered an uncontained engine failure as a result of a fatigue crack in a turbine disk in the number 2 engine (above the tail). The aircraft ultimately crash-landed at Sioux Gateway Airport, in Sioux City, Iowa
According to the NTSB report – The No.2 engine fragments severed the No.1 and No.3 hydraulic system lines, and the forces of the engine failure fractured the No.2 hydraulic system rendering the airplanes three hydraulic-powered flight control systems inoperative.
The airplane was marginally flyable using asymetric thrust from engines No.1 and No.3 after the loss of all conventional flight control systems – however, a safe landing was virtually impossible.
Although this crash was caused by mechanical failure, there were human factors involved where a fatigue crack was not detected (when it should have) in a critical part of the engine that eventually led to the uncontained engine failure.
The NTSB report says that the airplane touched down on the threshold slightly to the left of the centerline on runway 22 at 1600 at Sioux city airport. First ground contact was made by the right wing tip followed by the right main landing gear.
The airplane skidded to the right of the runway and rolled to an inverted position. Witnesses observed the airplane ignite and cartwheel, coming to rest after crossing runway 17/35. Firefighting and rescue operations began immediately, but the airplane was destroyed by impact and fire.
Of the 285 passengers and 11 crew, it is remarkable that 182 made it out alive given that the aircraft was pretty much uncontrollable having lost all hydraulic systems which rendered the primary flight controls useless.
Weather
Weather accounts for roughly 10% of fatal crashes.
The Federal Aviation Administration (FAA) Aviation Safety Information Analysis and Sharing (ASIAS) analysts performed a study of the National Transportation Safety Board (NTSB) looking at aviation weather-related accidents between 2003- 2007.
From the report, the largest contributor to weather accidents is the wind with most incidents happening during the landing phase, closely followed by the take-off phase.
The weather tends to affect smaller aircraft rather than larger aircraft with smaller aircraft having roughly 20 times the rate of weather-related accidents compared to larger airliners.
A Delta airlines Lockheed L1011 (Flight 191) crashed at Dallas Fort Worth International on 2nd August 1985 after flying through a thunderstorm producing a microburst. The aircraft experienced extreme windshear (at least 73knots horizontally and maximum updraft of 25fps and 49fps).
The NTSB report into flight 191 found that as a result of the windshear the aircraft initially touch down before the runway – hitting a car on a highway and then struck two water tanks at the airport and then breaking up.
The next major contributor to aviation weather-related aviation accidents was low cloud and surprisingly the bulk of accidents occurred during the cruise phase. Controlled flight into terrain is a major cause of plane crashes in low cloud.
As a pilot, the weather is the first item I’ll check before any flying day because of the amount it impacts and influences the operation. Air travel can be executed safely, even in the most challenging conditions provided good safe conservative decisions are being made.
Sabotage
This is probably the most terrifying even for a plane crash, given how little control there is and often sabotage can take place without warning.
PlaneCrashInfo.com has 9% and plane crashes down to sabotage.
Terrorism
The most current threat is Terrorism. The terrible events of 9/11 remain on everyone’s mind. Part of the improvements in air travel to avoid a repeat of 9/11 hijack plane crashes include enhanced passenger security checks.
Since 9/11, aircraft flight deck doors have been improved to resist forcible intrusion with locks and tighter procedures to prevent unauthorised access to the flight deck.
Ethiopian Airlines B767-200ER – flight 961 after being hijacked on 23rd November 1996, ran out of fuel and crashed close to the shoreline of the Comoros islands whilst attempting to ditch.
With only 2 hours of fuel on board, the hijackers demanded to be flown to Australia which was over 6 hours flight time away. Despite pleas to land and refuel the aircraft in Mombassa, the hijackers refused.
The hijackers had access to the aircraft fire crash axe and one of the recommendations from the crash investigation report was for the crash axe to be stored in such a way as to make it inaccessible to flight crew members.
Of the 175 passengers and crew, there were 125 fatalities.
Military conflict
Military conflict has caused plane crashes, such as the downing of Malaysia Airlines flight 17 in Ukraine in 2014.
Suicide
On the 24th March 2015, a German wings Airbus A320 crashed into the Alps in France killing all 144 passengers and 6 crewmembers. The final report published by the BEA investigation of the crash found that the co-pilot was showing symptoms consistent with a psychotic depressive episode.
No action could have been taken by the authorities and/or his employer to prevent him from flying on the day of the accident, because they were informed by neither the co-pilot himself, nor by anybody else, such as a physician, a colleague, or a family member.
In the cruise phase, the co-pilot waited until he was alone in the flight deck before intentionally programming the autopilot to enter into a decent. The co-pilot kept the door locked during the descent until the aircraft hit terrain in the French Alps.
Security of the cockpit door (post 9/11 recommendations) made it pretty much impossible for anyone to enter the flight deck to intervene.
Procedures vary by airline but most companies dictate that when one pilot leaves the flight deck, the other pilot can not be left alone. Another member of the crew would need to go to the flight deck to minimise the chances of a similar occurrence happening again.
After the accident, the BEA made safety recommendations in the following areas below (taken from the report:
- medical evaluation of pilots with mental health issues; routine analysis of in-flight incapacitation;
- mitigation of the consequences of loss of licence;
- anti-depressant medication and flying status;
- balance between medical confidentiality and public safety; promotion of pilot support programmes.
Other mistakes
From PlaneCrashInfo.com – around 10% of plane crashes are caused by other mistakes such as:
- Air Traffic Control Errors
- Ground crew mistakes
- Improperly loaded cargo
- Bird stikes
- Fuel contamination
- Obstructions on the runway
On 1st July 2002, a Boeing B757-200 collided with a Tupelov TU154M in midair near Lake Constance with 71 fatalities and both aircraft being destroyed. Both aircraft were on a collision course at right angles at the same level (FL360).
Due to works being carried out on the radar system, some of the warning systems ordinarily available were not on the evening of the crash.
The report from the German Federal Bureau of Aircraft Accidents Investigation found the causes to be as follows:
- Imminent seperation infringement was not noticed by ATC in time. The instruction for the TU154M to descend was given at a time when the prescribed seperation to the B757-200 could not be ensured anymore
The Traffic Collision Avoidance System (TCAS) activated on both aircraft. The TCAS system instructed the B757-200 was to descend (which the crew did) but contrary to normal practice the TCAS system instructed the TU154M to climb but the crew continued to descend as they had been instructed by ATC a few moments earlier.
The investigation report found that as the situation developed between the B757-200 and the TU154M, the controller’s attention continued to be taken up by an unrelated A320 aircraft that had been trying to get in touch with the controller.
From all the accidents mentioned, it is very seldom one single cause that causes an air crash, but a number of different ‘chance’ events that all, unfortunately, conspire to cause an accident.
On the 29th of April 2013, National Airlines flight 102 Boeing 747 freighter crashed a few moments after takeoff from Bagram Airfield in Afghanistan killing everyone on board.
The cause was found to be improperly secured cargo that broke free during the takeoff rolled back, damaging the rear bulkhead and in turn disabling the flight control system making recovery from the ensuing stall (as a result of the cargo shifting) impossible.
Can you actually survive a plane crash?
According to a report by the NTSB analysing aircraft accidents from 1983 to 2000, the National Transportation Safety Board found that the survival rate of crashes was 95.7%
Catastrophic plane crashes that involve loss of life are extremely rare- 1 in 19.8 million – if you fly with airlines with a good safety record (planecrashinfo.com).
There are plane crashes where unfortunately everyone dies, but despite what is said in the press, these events are extremely rare.
The NTSB found that even in serious accidents where fire and substantial damage occurred, 76.6% of passengers still survived.
How do most plane crashes happen?
Most plane crashes happen during the takeoff and landing phases. PlaneCrashInfo.com found that a study by Boeing looking at commercial jet aeroplane accidents between 1959 and 2008 said 20% of accidents happened during the takeoff and initial climb.
36% of accidents also happened between the final approach and landing phase. The likely reason for around 56% of accidents taking place in either the takeoff and landing phase is likely to be because of the following:
- The aircraft is much closer to the ground giving the crews less time to react
- Workload of pilots is typically much higher during the take off and landing phase
- There is much more interaction between air traffic control, ground staff and other aircraft during the initial part of the flight
- The crew have maximum exposure to weather at lower levels. Difficult weather conditions can include strong crosswinds, low visibilty, low cloud or icing conditions
- As the aircraft transitions into the cruise phase and its final cruise altitude, the workload reduces on crews and they generally have much more thinking time
If we consider each phase in turn – these are some of the risks associated:
Push back and taxi
There are other aircraft around and most large airports can be congested.
Take off roll
This is probably the most critical phase of the departure. As the aircraft speed increases the dangers associated with rejecting a take-off increase until the takeoff decision speed.
This speed is called V1. Above V1, the aircraft is committed to getting airborne as there is insufficient runway remaining to be able to stop.
At high speeds close to V1, should a problem arise, there is very little thinking time and if the take-off is to be rejected successfully, then prompt and correct actions are needed by the flight crew to stop the aircraft.
Research has found that for most problems, it is safer to take the problem into the air, assess the situation and take corrective action, then return to land at a lower landing weight with the luxury of a full length of runway ahead to stop.
You will appreciate that there is not a great amount of thinking time during the take-off roll.
Initial climb
The workload is high going through all the items necessary to transition from take-off to cruise phase. In addition, crews will be navigating, communicating with ATC as they try to keep aircraft apart in the busy airspace.
Initial approach
Similar to the initial climb, crews have increased workload, terrain and weather may have a bearing on the flight. The biggest cause of plane crashes is pilot error. As the aircraft gets closer to the ground the less thinking time there is available with less opportunity to recover from a catastrophic event.
Landing
The landing is a critical phase where many elements come together. High workload, terrain, weather – crosswinds, visibility, low cloud, rain, snow etc. Runway condition is also a determining factor. All these items increase the risk of a plane crash if the aircraft gets into an undesired state.
Despite all these issues, according to the National Transportation Safety Board, passengers still have a 95% chance of surviving a plane accident.
How likely is it for your plane to crash?
According to planecrashinfo.com the odds of being in a fatal accident (assuming flying on airlines with a good safety record) are 1 in 10 million. The odds of being killed on a single flight flying on airlines with a good safety record are 1 in 19.8 million.
The odds are significantly worse though when flying on airlines with a poor safety record. The odds of being on a flight that results in at least 1 fatality flying on airlines with a poor safety record are 1 in 1.5 million. The odds of being killed on a single flight on an airline with a poor safety record is 1 in 2 million.
These stats are based on 20 years of data (1993-2012) from the information contained in OAG Aviation & PlaneCrashInfo.com accident databases.
Sources
Bennett, Simon Ashley. “The five most common reasons for airliner disasters.” The Conversation. Nov. 2, 2015. (3rd January 2022) https://theconversation.com/the-five-most-common-reasons-for-airliner-disasters-50100
Bureau Enquêtes-Accidents. “Accident on 25 July 2000 at La Patte d’Oie in Gonesse (95) to the Concorde registered F-BTSC operated by Air France.” (3rd January 2022) https://www.bea.aero/uploads/tx_elydbrapports/f-sc000725a.pdf
Bureau Enquêtes-Accidents. “Final Report Accident on 24 March 2015 at Prads-Haute-Bléone (Alpes-de-Haute-Provence, France) to the Airbus A320-211 registered D-AIPX operated by Germanwings”. (3rd January 2022) https://www.bea.aero/uploads/tx_elydbrapports/BEA2015-0125.en-LR.pdf
planecrashinfo.com. “Causes of Fatal Accidents by Decade.” PlaneCrashInfo.com. (3rd January 2022) http://www.planecrashinfo.com/cause.htm
Federal Aviation Administration (FAA) Aviation Safety Information Analysis and Sharing (ASIAS). “Weather-Related Aviation Accident Study 2003-2007.” Faa.gov. Feb. 2, 2010. (3rd January 2022) https://www.asias.faa.gov/i/studies/2003-2007weatherrelatedaviationaccidentstudy.pdf
National Transport Safety Board. “Aircraft Accident Report, Delta Airlines Inc, Lockheed L1011-385-1, N726DA Dallas/Fort Worth International Airport Texas.” August 2, 1985 (3rd January 2022) https://www.ntsb.gov/investigations/AccidentReports/Reports/AAR8605.pdf
Kudzi Chikohora is a B737 captain with over 3,000 hours of flying in Europe. He holds a Master’s degree in Aerospace Engineering, is a chartered engineer, and is a member of the Royal Aeronautical Society.
Kudzi completed his pilot training via the self-funded modular pilot training route and created kcthepilot.com to share pilot training and aviation content.
