Aviation safety

Aviation safetyis the study and practice of managing risks in aviation. This includes preventingaviation accidents and incidentsthrough research, educating air travel personnel, passengers and the general public, as well as the design of aircraft and aviation infrastructure. The aviation industry is subject to significant regulation and oversight.

AnAir Maltacrewman performing apre-flight inspectionof anAirbus A320.

Aviation securityis focused on protecting air travelers, aircraft and infrastructure from intentional harm or disruption, rather than unintentional mishaps.

Statistics

Evolution

Yearly fatalitiessince 1942, 5 year average in red: fatalities peaked in 1972.

Fatalities per trillionrevenue passenger kilometressince 1970 (five-year moving average for fatalities)

Aviationis safer today than it has ever been. Modern commercial aviation boasts an accident rate of approximately 1 fatal accident per 16 million flights, far lower than historic numbers.

On December 14, 1903, theWright Brothersconducted a test flight of their powered airplane from slope of Big Kill Devil Hill in North Carolina. Upon takeoff, the airplane lifted about 15 feet off the ground, stalled, and crashed into the sand.Only three days later, on December 17, 1903, Wilbur's brother,Orville Wright,would fly the airplane for the world's first powered, sustained, and controlled heavier-than-air flight in history. Although the failed test flight on December 14 would be mostly forgotten in aviation, it remains to this day one of the firstaviation accidentsin history.

In the early years of air travel, accidents were exceedingly common. 1929 was named the year of "The Great Crash" due to the frequency of aircraft accidents that occurred during the year, with 24 fatal accidents reported.In 1928 and 1929, the overall accident rate was about 1 in every million miles (1.6 million kilometers) flown.In today's industry, that accident rate would translate to about 7,000 fatal accidents each year.

For the ten-year period 2002 to 2011, 0.6 fatal accidents happened per one million flights globally, 0.4 per million hours flown, 22.0 fatalities per one million flights or 12.7 per million hours flown.

From 310 million passengers in 1970, air transport had grown to 3,696 million in 2016, led by 823 million in the United States, then 488 million inChina. In 2016, there were 19 fatal accidents of civil airliners of more than 14 passengers, resulting in 325 fatalities, the second safest year ever after 2015 with 16 accidents and 2013 with 265 fatalities. For planes heavier than 5.7 t, there were 34.9 million departures and 75 accidents worldwide with 7 of these fatal for 182 fatalities, the lowest since 2013: 5.21 fatalities per million departures.

Stage of flight in which incidents occur, according toNational Transportation Safety Boarddata from 2006 to 2023

In 2017, there were 10 fatal airliner accidents, resulting in 44 occupant fatalities and 35 persons on the ground: the safest year ever for commercial aviation, both by the number of fatal accidents as well as in fatalities. By 2019, fatal accidents per million flights decreased 12 fold since 1970, from 6.35 to 0.51, and fatalities per trillionrevenue passenger kilometre(RPK) decreased 81 fold from 3,218 to 40.

Typology

Runway safety represents 36% of accidents, ground safety 18% and loss of control in-flight 16%.

Loss of controlinflight represents 35% of the fatal accidents,Controlled flight into terrain21%,runway excursions17%, system orcomponent failure:6%, Touchdown off therunway:5%,Abnormal Runway Contact:4% andfire:2%.

Safety has improved from betteraircraft design process,engineering and maintenance, the evolution of navigation aids, and safety protocols and procedures.

Transport comparisons

There are three main ways in which the risk of fatality in a certain mode of travel can be measured: (1) deaths per billion typicaljourneystaken, (2) deaths per billionhourstraveled, and (3) deaths per billionkilometerstraveled. The following table displays these statistics for the United Kingdom (1990–2000),and has been appended. (Note that aviation safety does not include travelling to the airport.)

Transportation type	Deaths per billion
	Journeys	Hours	Kilometers
Bus	4.3	11.1	0.4
Rail	20	30	0.6
Van	20	60	1.2
Private Car	40	130	3.1
Foot	40	220	54.2
Water	90	50	2.6
Air	117	30.8	0.05
Pedal cycle	170	550	44.6
Motorcycle	1640	4840	108.9
Paragliding		8850
Skydiving	7500	75000
Space Shuttle	17000000	70000	6.6

The first two statistics are computed for typical travels by their respective forms of transport, so they cannot be used directly to compare risks related to different forms of transport in a particular travel "from A to B". For example, these statistics suggest that a typical flight fromLos AngelestoNew Yorkwould carry a larger risk factor than a typical car travel from home to office. However, car travel from Los Angeles to New York would not be typical; that journey would be as long asseveral dozentypical car travels, and thus the associated risk would be larger as well. Because the journey would take a much longer time, the overall risk associated with making this journey by car would be higher than making the same journey by air, even if each individual hour of car travel is less risky than each hour of flight.

For risks associated with long-range intercity travel, the most suitable statistic is the third one: deaths per billion kilometers. Still, this statistic can lose credence in situations where the availability of an air option makes an otherwise inconvenient journey possible.

Aviation industry insurers base their calculations on thedeaths per journeystatistic while the aviation industry itself generally uses thedeaths per kilometrestatistic in press releases.

Since 1997, the number of fatal air accidents has been no more than 1 for every 2,000,000,000 person-milesflown,and thus is one of the safest modes of transportation when measured bydistance traveled.

The Economistnotes that air travel is safer by distance travelled, but trains are as safe as planes.It also notes that cars are four times more hazardous for deaths per time travelled, and cars and trains are respectively three times and six times safer than planes by number of journeys taken.

Because the above figures are focused on providing a perspective to the realm of everyday transportation, air travel is taken to include only standard civil passenger aviation, as offered commercially to the general public. Military and special-purpose aircraft are excluded.

United States

Between 1990 and 2015, there were 1874 commuter andair taxiaccidents in the U.S. of which 454 (24%) were fatal, resulting in 1296 deaths, including 674 accidents (36%) and 279 fatalities (22%) in Alaska alone.

The number of deaths per passenger-mile on commercial airlines in the United States between 2000 and 2010 was about 0.2 deaths per 10 billion passenger-miles.For driving, the rate was 150 per 10 billion vehicle-miles for 2000: 750 times higher per mile than for flying in a commercial airplane.

There were no fatalities on large scheduled commercial airlines in the United States for over nine years, between theColgan Air Flight 3407crash in February 2009, and a catastrophic engine failure onSouthwest Airlines Flight 1380in April 2018.

Security

Another aspect of safety is protection from intentional harm orproperty damage,also known assecurity.

Theterrorist attacksof 2001 are not counted as accidents. However, even if they were counted as accidents they would have added about 1 death per billion person-miles. Two months later,American Airlines Flight 587crashed in New York City, killing 265 people, including 5 on the ground, causing 2001 to show a very high fatality rate. Even so, the rate that year including the attacks (estimated here to be about 4 deaths per billion person-miles), is safe compared to some other forms of transport when measured by distance traveled.

Developments

Before WWII

The first aircraft electrical or electronic deviceavionicssystem wasLawrence Sperry'sautopilot,demonstrated in June 1914.TheTranscontinental Airway Systemchain of beacons was built by theCommerce Departmentin 1923 to guideairmailflights.

Gyrocopterswere developed byJuan de la Ciervato avoidstallandspinaccidents, and for that inventedcyclic and collectivecontrols used byhelicopters.The first flight of a gyrocopter was on 17 January 1923.

During the 1920s, the first laws were passed in the United States of America to regulatecivil aviation,notably theAir Commerce Act of 1926,which required pilots and aircraft to be examined and licensed, for accidents to be properly investigated, and for the establishment of safety rules and navigation aids; under the Aeronautics Branch of theUnited States Department of Commerce(US DoC).

A network ofaerial lighthouseswas established in the United Kingdom and Europe during the 1920s and 1930s.Use of the lighthouses has declined with the advent of radio navigation aids such asnon-directional beacon(NDB),VHF omnidirectional range(VOR), anddistance measuring equipment(DME). The last operational aerial lighthouse in the United Kingdom is on top of thecupolaover theRAF Collegemain hall atRAF Cranwell.

One of the first aids forair navigationto be introduced in the United States in the late 1920s wasairfield lighting,to assist pilots in making landings in poor weather or after dark. ThePrecision Approach Path Indicator(PAPI) was developed from this in the 1930s, indicating to the pilot the angle of descent to the airfield. This later became adopted internationally through the standards of theInternational Civil Aviation Organization(ICAO).

Jimmy Doolittledevelopedinstrument ratingand made his first 'blind' flight in September 1929. The March 1931 wooden wing failure ofa Transcontinental & Western Air Fokker F-10carryingKnute Rockne,coach of theUniversity of Notre Dame's football team, reinforced all-metalairframesand led to a more formalaccident investigationsystem.

On 4 September 1933, aDouglas DC-1test flight was conducted with one of the two engines shut down during the takeoff run, climbed to 8,000 feet (2,438 metres), and completed its flight, proving twinaircraft enginesafety. With greater range than lights and weather immunity,radio navigationaids were first used in the 1930s, like the AustralianAeradio stationsguiding transport flights, with a light beacon and a modifiedLorenz beamtransmitter (the German blind-landing equipment preceding the moderninstrument landing system- ILS).ILS was first used by a scheduled flight to make a landing in a snowstorm atPittsburgh, Pennsylvania,in 1938, and a form of ILS was adopted by the ICAO for international use in 1949.

Post-WWII

Hardrunwayswere built worldwide for World War II to avoid waves and floating hazards plaguingseaplanes.

Developed by the U.S. and introduced during World War II,LORANreplaced the sailors' less reliablecompassandcelestial navigationover water and survived until it was replaced by theGlobal Positioning System.

An airbornepulse-Doppler radarantenna. Some airborne radars can be used asmeteorological radars.

Following the development ofradar in World War II,it was deployed as a landing aid for civil aviation in the form ofground-controlled approach(GCA) systems then as theairport surveillance radaras an aid toair traffic controlin the 1950s.

A number of ground-basedweather radarsystems can detect areas of severe turbulence.

A modernHoneywellIntuvue weather system visualizes weather patterns up to 300 miles (480 km) away.

Distance measuring equipment(DME) in 1948 andVHF omnidirectional range(VOR) stations became the main route navigation means during the 1960s, superseding the low frequency radio ranges and thenon-directional beacon(NDB): the ground-based VOR stations were often co-located with DME transmitters and the pilots could establish their bearing and distance to the station.

Jetliners

To highlight thejetlinerevolution,Airbussplit them in four generations:

1. from 1952, early jets (Comet,Caravelle,BAC-111,Trident,B707,DC-8...) have dials and gaugescockpitsand early auto-flight systems;
2. from 1964, new designs (A300,F28,BAe 146,B727,originalB737andB747,L-1011,DC-9,DC-10...) have more elaborateautopilotandautothrottlesystems;
3. From 1980,glass cockpit&FMSdesigns (A310/A300-600,F100,B737 Classic& NG/MAX,B757/B767,B747-400/-8,Bombardier CRJ,Embraer ERJ,MD-11,MD-80/MD-90...) have improved navigation performance andTerrain Avoidance Systems,to reduceCFITaccidents;
4.  From 1988,Fly-By-Wire(in theA220,A320 family,A330/A340,A350,A380,B777,B787andEmbraer E-Jets) enabledflight envelope protectionto reduceLOCin flight accidents.

The fatal accident rate fell from 3.0 per million flights for the first generation to 0.9 for the next, 0.3 for the third and 0.1 for the last.

With the arrival ofWide Area Augmentation System(WAAS), satellite navigation has become accurate enough for altitude as well as positioning use, and is being used increasingly for instrument approaches as well as en-route navigation. However, because the GPS constellation is asingle point of failure,on-boardInertial Navigation System(INS) or ground-based navigation aids are still required for backup.

In 2017,Rockwell Collinsreported it had become more costly to certify than to develop a system, from 75% engineering and 25% certification in past years. It calls for a global harmonization between certifying authorities to avoid redundant engineering and certification tests rather than recognizing the others approval and validation.

Groundings of entire classes of aircraft out of equipment safety concerns is unusual, but this has occurred to thede Havilland Cometin 1954 after multiple crashes due to metal fatigue and hull failure, theMcDonnell Douglas DC-10in 1979 after the crash ofAmerican Airlines Flight 191due to engine loss, theBoeing 787 Dreamlinerin 2013 after itsbattery problems,and theBoeing 737 MAX in 2019after two crashes preliminarily tied to a flight control system.

Hazards

Unapproved parts

Main article:Unapproved aircraft part

Parts manufactured without an aviation authority's approval are described as "unapproved". Unapproved parts include inferior counterfeits, those used beyond their time limits, those that were previously approved but not properly returned to service, those with fraudulent labels, production overruns that were not sold with the agency's permission, and those that are untraceable.Unapproved faulty parts have caused hundreds of incidents and crashes, some fatal, including about 24 crashes between 2010 and 2016.

Foreign object debris

Main article:Foreign object debris

Foreign object debris (FOD) includes items left in the aircraft structure during manufacture/repairs, debris on the runway and solids encountered in flight (e.g. hail and dust). Such items can damage engines and other parts of the aircraft. In 2000,Air France Flight 4590crashed after hitting a part that had fallen from a departing Continental Airlines DC-10.

Misleading information and lack of information

A pilot misinformed by a printed document (manual, map, etc.), reacting to a faulty instrument or indicator (in the cockpit or on the ground),or following inaccurate instructions or information from flight or ground control can losesituational awareness,or make errors, and accidents or near misses may result.The crash ofAir New Zealand Flight 901was a result of receiving and interpreting incorrect coordinates, which caused the pilots to inadvertently fly into a mountain.

Lightning

Boeing studies showed that airliners are struck bylightningtwice per year on average; aircraft withstand typical lightning strikes without damage.

The dangers of more powerfulpositive lightningwere not understood until the destruction of agliderin 1999.It has since been suggested that positive lightning might have caused the crash ofPan Am Flight 214in 1963. At that time, aircraft were not designed to withstand such strikes because their existence was unknown. The 1985 standard in force in the US at the time of the glider crash, Advisory Circular AC 20-53A,was replaced by Advisory Circular AC 20-53B in 2006.However, it is unclear whether adequate protection against positive lightning was incorporated.

The effects of typical lightning on traditional metal-covered aircraft are well understood and serious damage from a lightning strike on an airplane is rare. Modern airliners like theBoeing 787 Dreamlinerwith exteriors and wings made fromcarbon-fiber-reinforced polymerhave been tested and shown to receive no damage from lightning strikes during testing.

Ice and snow

Snowbuilding on the intake to aRolls-Royce RB211engine of aBoeing 747-400.Snow and ice present unique threats and aircraft operating in these weather conditions often require de-icing equipment.

Ice andsnowcan be major factors in airline accidents. In 2005,Southwest Airlines Flight 1248slid off the end of arunwayafter landing in heavy snow conditions, killing one child on the ground.

Even a small amount oficingor coarsefrostcan greatly impair the ability of a wing to develop adequatelift,which is why regulations prohibit ice, snow or even frost on the wings or tail, prior to takeoff.Air Florida Flight 90crashed on takeoff in 1982, as a result of ice/snow on its wings.

An accumulation of ice during flight can be catastrophic, as evidenced by the loss of control and subsequent crashes ofAmerican Eagle Flight 4184in 1994, andComair Flight 3272in 1997. Both aircraft wereturbopropairliners, with straight wings, which tend to be more susceptible to inflight ice accumulation, than are swept-wing jet airliners.

Airlines and airports ensure that aircraft are properlyde-icedbeforetakeoffwhenever the weather involvesicing conditions.Modern airliners are designed to prevent ice buildup onwings,engines,and tails (empennage) by either routing heated air fromjet enginesthrough theleading edgesof the wing, and inlets,or on slower aircraft, by use of inflatable rubber "boots"that expand to break off any accumulated ice.

Airline flight plans requireairline dispatch officesto monitor the progress of weather along the routes of their flights, helping thepilotsto avoid the worst of inflight icing conditions. Aircraft can also be equipped with anice detectorin order to warn pilots to leave unexpected ice accumulation areas, before the situation becomes critical.Pitot tubesin modern airplanes and helicopters have been provided with the function of "Pitot Heating" to prevent accidents likeAir France Flight 447caused by the pitot tube freezing and giving false readings.

Wind shear or microburst

Effect of wind shear on aircraft trajectory. Note how merely correcting for the initial gust front can have dire consequences.

Awind shearis a change in wind speed and/or direction over a relatively short distance in the atmosphere. Amicroburstis a localized column of sinking air that drops down in a thunderstorm. Both of these are potential weather threats that may cause an aviation accident.

Wreckage ofDelta Air Lines Flight 191tail section after a microburst slammed the aircraft into the ground.

Strong outflow from thunderstorms causes rapid changes in the three-dimensional wind velocity just above ground level. Initially, this outflow causes a headwind that increases airspeed, which normally causes a pilot to reduce engine power if they are unaware of the wind shear. As the aircraft passes into the region of the downdraft, the localized headwind diminishes, reducing the aircraft's airspeed and increasing its sink rate. Then, when the aircraft passes through the other side of the downdraft, the headwind becomes a tailwind, reducing lift generated by the wings, and leaving the aircraft in a low-power, low-speed descent. This can lead to an accident if the aircraft is too low to effect a recovery before ground contact. Between 1964 and 1985, wind shear directly caused or contributed to 26 major civil transport aircraft accidents in the U.S. that led to 620 deaths and 200 injuries.

Engine failure

Further information:Turbine engine failureandETOPS

An engine may fail to function because offuel starvation(e.g.British Airways Flight 38),fuel exhaustion(e.g.Air Canada Flight 143),foreign object damage(e.g.US Airways Flight 1549), mechanical failure due tometal fatigue(e.g.Kegworth air disaster,El Al Flight 1862,China Airlines Flight 358), mechanical failure due to improper maintenance (e.g.American Airlines Flight 191), mechanical failure caused by an original manufacturing defect in the engine (e.g.Qantas Flight 32,United Airlines Flight 232,Delta Air Lines Flight 1288), and pilot error (e.g.Pinnacle Airlines Flight 3701).

In a multi-engine aircraft, failure of a single engine usually results in a precautionary landing being performed, for example, landing at adiversion airportinstead of continuing to the intended destination. Failure of a second engine (e.g.US Airways Flight 1549) or damage to other aircraft systems caused by an uncontained engine failure (e.g.United Airlines Flight 232) may, if anemergency landingis not possible, result in the aircraft crashing.

Structural failure of the aircraft

Examples of failure of aircraft structures caused bymetal fatigueinclude thede Havilland Cometaccidents (1950s) andAloha Airlines Flight 243(1988). Improper repair procedures can also cause structural failures includeJapan Airlines Flight 123(1985) andChina Airlines Flight 611(2002). Now that the subject is better understood, rigorous inspection andnondestructive testingprocedures are in place.

Composite materialsconsist of layers offibersembedded in aresinmatrix. In some cases, especially when subjected tocyclic stress,the layers of the material separate from each other (delaminate) and lose strength. As the failure develops inside the material, nothing is shown on the surface; instrument methods (oftenultrasound-based) have to be used to detect such a material failure. In the 1940s severalYakovlev Yak-9sexperienced delamination ofplywoodin their construction.

Stalling

Stallingan aircraft (increasing theangle of attackto a point at which the wings fail to produce enoughlift) is dangerous and can result in a crash if the pilot fails to make a timely correction.

Devices to warn the pilot when the aircraft's speed is decreasing close to the stall speed include stall warning horns (now standard on virtually all powered aircraft),stick shakers,and voice warnings. Most stalls are a result of the pilot allowing the airspeed to be too slow for the particular weight and configuration at the time. Stall speed is higher when ice or frost has attached to the wings and/or tail stabilizer. The more severe the icing, the higher the stall speed, not only because smooth airflow over the wings becomes increasingly more difficult, but also because of the added weight of the accumulated ice.

Crashes caused by a full stall of the airfoils include:

• British European Airways Flight 548(1972)
• United Airlines Flight 553(1972)
• Aeroflot Flight 7425(1985)
• Arrow Air Flight 1285(1985)
• Northwest Airlines Flight 255(1987)
• ThePaul Wellstonecrash (2002)
• Colgan Air Flight 3407(2009)
• Turkish Airlines Flight 1951crash (2009)
• Air France Flight 447(2009)

Fire

NASA air safety experiment (CID project)

Safety regulations control aircraft materials and the requirements for automated fire safety systems. Usually these requirements take the form of required tests. The tests measureflammabilityof materials andtoxicityofsmoke.When the tests fail, it is on a prototype in an engineering laboratory rather than in an aircraft.

Fire and its toxic smoke have been the cause of accidents. An electrical fire onAir Canada Flight 797in 1983 caused the deaths of 23 of the 46 passengers, resulting in the introduction of floor level lighting to assist people to evacuate a smoke-filled aircraft. In 1985, a fire on the runway caused the loss of 55 lives, 48 from the effects of incapacitating and subsequently lethal toxic gas and smoke in theBritish Airtours Flight 28Maccident which raised serious concerns relating to survivability – something that had not been studied in such detail. The swift incursion of the fire into the fuselage and the layout of the aircraft impaired passengers' ability to evacuate, with areas such as the forward galley area becoming a bottle-neck for escaping passengers, with some dying very close to the exits. Much research into evacuation and cabin and seating layouts was carried out atCranfield Instituteto try to measure what makes a good evacuation route, which led to the seat layout byOverwing exitsbeing changed by mandate and the examination of evacuation requirements relating to the design of galley areas. The use ofsmoke hoodsor misting systems were also examined although both were rejected.

South African Airways Flight 295was lost in the Indian Ocean in 1987 after an in-flight fire in the cargo hold could not be suppressed by the crew. The cargo holds of most airliners are now equipped with automatedhalonfire extinguishing systems to combat a fire that might occur in the baggage holds. In May 1996,ValuJet Flight 592crashed into the FloridaEvergladesa few minutes after takeoff because of a fire in the forward cargo hold. All 110 people on board were killed.

At one time, fire fightingfoam pathswere laid down before an emergency landing, but the practice was considered only marginally effective, and concerns about the depletion of firefighting capability due to pre-foaming led the United States FAA to withdraw its recommendation in 1987.

One possible cause of fires in airplanes is wiring problems that involve intermittent faults, such as wires with breached insulation touching each other, having water dripping on them, or short circuits. Notable wasSwissair Flight 111in 1998 due to an arc in the wiring ofIFEwhich ignited flammableMPETinsulation. These are difficult to detect once the aircraft is on the ground. However, there are methods, such asspread-spectrum time-domain reflectometry,that can feasibly test live wires on aircraft during flight.

Bird strike

Main article:Bird strike

Bird strikeis an aviation term for a collision between a bird and an aircraft. Fatal accidents have been caused by both engine failure following bird ingestion and bird strikes breaking cockpit windshields.

Jet engines have to be designed to withstand the ingestion of birds of a specified weight and number and to not lose more than a specified amount of thrust. The weight and numbers of birds that can be ingested without hazarding the safe flight of the aircraft are related to the engine intake area.The hazards of ingesting birds beyond the "designed-for" limit were shown onUS Airways Flight 1549when the aircraft struck Canada geese.

The outcome of an ingestion event and whether it causes an accident, be it on a small fast plane, such as military jet fighters, or a large transport, depends on the number and weight of birds and where they strike the fan blade span or the nose cone. Core damage usually results with impacts near the blade root or on the nose cone.

The highest risk of a bird strike occurs during takeoff andlandingin the vicinity ofairports,and during low-level flying, for example by military aircraft, crop dusters and helicopters. Some airports use active countermeasures, including a person with ashotgun,playing recorded sounds of predators through loudspeakers, or employingfalconers.Poisonous grass can be planted that is not palatable to birds, nor to insects that attractinsectivorousbirds. Passive countermeasures involve sensibleland-use management, avoiding conditions attracting flocks of birds to the area (e.g.landfills). Another tactic found effective is to let the grass at the airfield grow taller (to approximately 12 inches or 30 centimetres) as some species of birds won't land if they cannot see one another.

Human factors

See also:Aviation medicine

NASA air safety experiment (CID project). The airplane is aBoeing 720testing a form of jet fuel, known as "antimisting kerosene",which formed a difficult-to-ignite gel when agitated violently, as in a crash.

Human factors,includingpilot error,are another potential set of factors, and currently the factor most commonly found in aviation accidents.Much progress in applying human factors analysis to improving aviation safety was made around the time ofWorld War IIby such pioneers asPaul FittsandAlphonse Chapanis.However, there has been progress in safety throughout the history of aviation, such as the development of the pilot'schecklistin 1937.CRM, orcrew resource management,is a technique that makes use of the experience and knowledge of the complete flight crew to avoid dependence on just one crew member, and to improvepilot decision making.

Pilot error and improper communication are often factors in thecollisionof aircraft. This can take placein the air(1978Pacific Southwest AirlinesFlight 182) (TCAS) or on the ground (1977Tenerife disaster) (RAAS). The barriers to effective communication have internal and external factors.The ability of the flight crew to maintainsituational awarenessis a critical human factor in air safety. Human factors training is available to general aviation pilots and calledsingle pilot resource managementtraining.

Failure of the pilots to properly monitor the flight instruments caused the crash ofEastern Air Lines Flight 401in 1972.Controlled flight into terrain(CFIT), and error during take-off and landing can have catastrophic consequences, for example causing the crash ofPrinair Flight 191on landing, also in 1972.

Pilot fatigue

Main article:Pilot fatigue

TheInternational Civil Aviation Organization(ICAO) defines fatigue as "A physiological state of reduced mental or physical performance capability resulting from sleep loss or extended wakefulness, circadian phase, or workload."The phenomenon places great risk on the crew and passengers of an airplane because it significantly increases the chance ofpilot error.Fatigue is particularly prevalent among pilots because of "unpredictable work hours, long duty periods,circadian disruption,and insufficient sleep ".These factors can occur together to produce a combination ofsleep deprivation,circadian rhythm effects, and 'time-on task' fatigue.Regulators attempt to mitigate fatigue by limiting the number of hours pilots are allowed to fly over varying periods of time. Experts in aviation fatigueoften find that these methods fall short of their goals.

Piloting while intoxicated

Rarely, flight crew members are arrested or subject to disciplinary action for beingintoxicatedon the job. In 1990, threeNorthwest Airlinescrew members were sentenced to jail for flying while drunk. In 2001, Northwest fired a pilot who failed abreathalyzertest after a flight. In July 2002, both pilots ofAmerica West Airlines Flight 556were arrested just before they were scheduled to fly because they had been drinking alcohol. The pilots were fired and the FAA revoked their pilot licenses.At least one fatal airliner accident involving drunk pilots occurred whenAero Flight 311crashed at Kvevlax, Finland, killing all 25 on board in 1961. Another example is the crashAeroflot Flight 821,in which the captain's intoxication contributed to the accident, killing all 88 on board.

Pilot suicide and murder

Main article:Suicide by pilot

There have been rare instances ofsuicide by pilots.Although most air crew arescreened for psychological fitness,a very few authorized pilots have flown acts of suicide and evenmass murder.

In 1982,Japan Airlines Flight 350crashed while on approach to the Tokyo Haneda Airport, killing 24 of the 174 on board. The official investigation found the mentally ill captain had attempted suicide by placing the inboard engines into reverse thrust, while the aircraft was close to the runway. The first officer did not have enough time to countermand before the aircraft stalled and crashed.

In 1997,SilkAir Flight 185suddenly went into a high dive from its cruising altitude. The speed of the dive was so high that the aircraft began to break apart before it finally crashed nearPalembang,Sumatra.After three years of investigation, the Indonesian authorities declared that the cause of the accident could not be determined. However, the US NTSB concluded that deliberate suicide by the captain was the only reasonable explanation.

In 1999 in the case ofEgyptAir Flight 990,it appears that thefirst officerdeliberately crashed into the Atlantic Ocean while the captain was away from his station.

Crew involvement isone of the speculative theoriesin the disappearance ofMalaysia Airlines Flight 370on 8 March 2014.

On 24 March 2015,Germanwings Flight 9525(anAirbus A320-200) crashed 100 kilometres (62 miles) north-west of Nice, in theFrench Alps,after a constant descent that began one minute after the last routine contact with air traffic control, and shortly after the aircraft had reached its assigned cruise altitude. All 144 passengers and six crew members were killed. The crash was intentionally caused by the co-pilot, Andreas Lubitz. Having been declared 'unfit to work' without telling his employer, Lubitz reported for duty, and during the flight locked the captain out of the flight-deck. In response to the incident and the circumstances of Lubitz's involvement, aviation authorities in Canada, New Zealand, Germany, and Australia implemented new regulations that require two authorised personnel to be present in the cockpit at all times. Three days after the incident, theEuropean Aviation Safety Agency(EASA) issued a temporary recommendation for airlines to ensure that at least two crew members, including at least one pilot, are in the cockpit at all times of the flight. Several airlines announced they had already adopted similar policies voluntarily.

Deliberate aircrew inaction

Inaction,omission,failure to act as required, willful disregard of safety procedures, disdain for rules, and unjustifiable risk-taking by pilots have also led toaccidents and incidents.

Although Smartwings QS-1125 flight of 22 August 2019 successfully made an emergency landing at destination, the captain was censured for failing to follow mandatory procedures, including for not landing at the nearest possible diversion airport after an engine failure.

Human factors of third parties

Unsafe human factors are not limited to pilot errors. Third party factors include ground crew mishaps, ground vehicle to aircraft collisions and engineering maintenance related problems. For example, failure to properly close a cargo door onTurkish Airlines Flight 981in 1974 caused the loss of the aircraft. (However, design of the cargo door latch was also a major factor in the accident.) In the case ofJapan Airlines Flight 123in 1985, improper repair of previous damage led to explosive decompression of the cabin, which in turn destroyed thevertical stabilizerand damaged all four hydraulic systems which powered all the flight controls.

Controlled flight into terrain

Main article:Controlled flight into terrain

Controlled flight into terrain(CFIT) is a class of accidents in which an aircraft is flown under control into terrain or man-made structures. CFIT accidents typically result from pilot error or of navigational system error. Failure to protectILS critical areascan also cause CFIT accidents.In December 1995,American Airlines Flight 965tracked off course while approachingCali,Colombia,and hit a mountainside despite aterrain awareness and warning system(TAWS) terrain warning in the cockpit and desperate pilot attempt to gain altitude after the warning. Crew position awareness and monitoring of navigational systems are essential to the prevention of CFIT accidents. As of February 2008,over 40,000 aircraft had enhanced TAWS installed, and they had flown over 800 million hours without a CFIT accident.

Another anti-CFIT tool is the Minimum Safe Altitude Warning (MSAW) system which monitors the altitudes transmitted by aircraft transponders and compares that with the system's defined minimum safe altitudes for a given area. When the system determines the aircraft is lower, or might soon be lower, than the minimum safe altitude, theair traffic controllerreceives an acoustic and visual warning and then alerts the pilot that the aircraft is too low.

Electromagnetic interference

See also:Mobile phones on aircraftandElectromagnetic interference

The use of certain electronic equipment is partially or entirely prohibited as it might interfere with aircraft operation,such as causingcompassdeviations.Use of some types of personal electronic devices is prohibited when an aircraft is below 10,000 feet (3,000 m), taking off, or landing. Use of amobile phoneis prohibited on most flights because in-flight usage creates problems with ground-based cells.Wireless devices such as cellphones feature anairplane mode.

Ground damage

Ground damage to an aircraft. Severalstringerswere cut and the aircraft was grounded

Variousground support equipmentoperate in close proximity to the fuselage and wings to service the aircraft and occasionally cause accidental damage in the form of scratches in the paint or small dents in the skin. However, because aircraft structures (including the outer skin) play such a critical role in the safe operation of a flight, all damage is inspected, measured, and possibly tested to ensure that any damage is within safe tolerances.

An example problem was the depressurization incident onAlaska Airlines Flight 536in 2005. During ground services, abaggage handlerhit the side of the aircraft with a tug towing a train ofbaggage carts.This damaged the metal skin of the aircraft. This damage was not reported and the plane departed. Climbing through 26,000 feet (7,900 m) the damaged section of the skin gave way under the difference in pressure between the inside of the aircraft and the outside air. The cabin depressurized explosively necessitating a rapid descent to denser (breathable) air and an emergency landing. Post-landing examination of the fuselage revealed a 12-inch (30 cm) hole on the right side of the airplane.

Volcanic ash

Main article:Volcanic ash and aviation safety

Plumes ofvolcanic ashnear activevolcanoescan damagepropellers,enginesand cockpit windows. In 1982,British Airways Flight 9flew through an ash cloud and temporarily lost power from all four engines. The plane was badly damaged, with all the leading edges being scratched. The front windscreens had been so badly "sand" blasted by the ash that they could not be used to land the aircraft.

Prior to 2010 the general approach taken by airspace regulators was that if the ash concentration rose above zero, then the airspace was considered unsafe and was consequently closed. Volcanic Ash Advisory Centersenable liaison betweenmeteorologists,volcanologists,and the aviation industry.

Runway safety

Airport safety car at an Airport in Taiwan.

Main article:Runway safety

Types of runway safety incidents include:

• Runway excursion– an incident involving only a single aircraft making an inappropriate exit from the runway.
• Runway overrun– a specific type of excursion where the aircraft does not stop before the end of the runway (e.g.,Air France Flight 358).
• Runway incursion– incorrect presence of a vehicle, person, or another aircraft on the runway (e.g.,Tenerife airport disaster).
• Runway confusion – crew misidentification of the runway for landing or take-off (e.g.,Comair Flight 5191,Singapore Airlines Flight 6).

Terrorism

Aircrew are normally trained to handlehijacksituations.Since theSeptember 11, 2001 attacks,stricterairportandairline securitymeasures are in place to preventterrorism,such as security checkpoints and locking the cockpit doors during flight.

In the United States, theFederal Flight Deck Officerprogram is run by theFederal Air Marshal Service,with the aim of training active and licensed airline pilots to carry weapons and defend their aircraft against criminal activity and terrorism. Upon completion of government training, selected pilots enter a covert law enforcement and counter-terrorism service. Their jurisdiction is normally limited to a flight deck or a cabin of a commercial airliner or a cargo aircraft they operate while on duty.

Military action

Passenger planes have rarely been attacked in both peacetime and war. Examples:

• In 1955, Bulgaria shot downEl Al Flight 402.
• In 1973, Israel shot downLibyan Arab Airlines Flight 114.
• In 1983, the Soviet Union shot downKorean Air Lines Flight 007.
• In 1988, the United States shot downIran Air Flight 655.
• In 2001, the Ukrainian Air Force accidentally shot downSiberia Airlines Flight 1812during an exercise.
• In 2014, Russia shot downMalaysia Airlines Flight 17.
• In 2020, Iran shot downUkraine International Airlines Flight 752.

Accident survivability

Further information:Pre-flight safety demonstration,Aircraft safety card,Brace position,Aircraft rescue and firefighting,andAirport crash tender

Earlier tragedies investigations and improved engineering has allowed many safety improvements that have allowed an increasing safer aviation.

Airport design

EMASbed after being run over by landing gear

Airport design and location can have a large impact on aviation safety, especially since some airports such asChicago Midway International Airportwere originally built for propeller planes and many airports are in congested areas where it is difficult to meet newer safety standards. For instance, the FAA issued rules in 1999 calling for arunway safety area,usually extending 150 metres (500 ft) to each side and 300 metres (1,000 ft) beyond the end of a runway. This is intended to cover ninety percent of the cases of an aircraft leaving the runway by providing a buffer space free of obstacles.Many older airports do not meet this standard. One method of substituting for the 300 metres (1,000 ft) at the end of a runway for airports in congested areas is to install anengineered materials arrestor system(EMAS). These systems are usually made of lightweight, crushable concrete that absorbs the energy of the aircraft to bring it to a rapid stop. As of 2008,they have stopped three aircraft atJFK Airport.

Emergency airplane evacuations

According to a 2000 report by theNational Transportation Safety Board,emergency aircraft evacuationshappen about once every 11 days in the U.S. While some situations are extremely dire, such as when the plane is on fire, in many cases the greatest challenge for passengers can be the use of theevacuation slide.In aTimearticle on the subject, Amanda Ripley reported that when a new supersized Airbus A380 underwent mandatory evacuation tests in 2006, thirty-three of the 873 evacuating volunteers got hurt. While the evacuation was considered a success, one volunteer suffered a broken leg, while the remaining 32 received slide burns. Such accidents are common. In her article, Ripley provided tips on how to make it down the airplane slide without injury. Another improvement to airplane evacuations is the requirement by theFederal Aviation Administrationfor planes to demonstrate an evacuation time of 90 seconds with half the emergency exits blocked for each type of airplane in their fleet. According to studies, 90 seconds is the time needed to evacuate before the plane starts burning, before there can be a very large fire or explosions, or before fumes fill the cabin.

Aircraft materials and design

Changes such as using new materials for seat fabric and insulation has given between 40 and 60 additional seconds to people on board to evacuate before the cabin gets filled with fire and potential deadly fumes.Other improvements through the years include the use of properly rated seatbelts, impact resistant seat frames, and airplane wings and engines designed to shear off to absorb impact forces.

Radar and wind shear detection systems

As the result of the accidents due to wind shear and other weather disturbances, most notably the 1985 crash ofDelta Air Lines Flight 191,the U.S.Federal Aviation Administrationmandated that all commercial aircraft haveon-board wind shear detection systemsby 1993.Since 1995, the number of major civil aircraft accidents caused by wind shear has dropped to approximately one every ten years, due to the mandated on-board detection as well as the addition of Dopplerweather radarunits on the ground (NEXRAD).The installation of high-resolutionTerminal Doppler Weather Radarstations at many U.S. airports that are commonly affected by wind shear has further aided the ability of pilots and ground controllers to avoid wind shear conditions.

Accidents and incidents

• List of airship accidents
• Lists of aviation accidents and incidents
• Aviation accidents and incidents
• List of airliner shootdown incidents
• Flight recorder,includesflight data recorderandcockpit voice recorder

National investigation organizations

• Australian Transport Safety Bureau
• Flugunfalluntersuchungsstelle im BMVITArchived2008-09-21 at theWayback Machine(Austria)
• Centro de Investigação e Prevenção de Acidentes Aeronáuticos(Brazil)
• Transportation Safety Board of Canada
• Air Accidents Investigation Institute(Czech Republic)
• Danish Aircraft Accident Investigation Board
• Bureau d'Enquêtes et d'Analyses pour la sécurité de l'Aviation Civile(France)
• Bundesstelle für Flugunfalluntersuchung(Germany)
• Aircraft Accident Investigation Bureau(India)
• KNKT - Komite Nasional Keselamatan Transportasi(Indonesia)
• International Civil Aviation Organization
• Air Accident Investigation Unit(Ireland)
• Agenzia Nazionale per la Sicurezza del Volo(Italy)
• Aircraft and Railway Accidents Investigation Commission(Japan)
• Civil Aviation Authority of New Zealand
• Transport Accident Investigation Commission(New Zealand)
• Onderzoeksraad voor Veiligheid(The Netherlands)
• Civil Aviation Authority of the Philippines
• South African Civil Aviation Authority(South Africa)
• Comisión de Investigación de Accidentes e Incidentes de Aviación Civil(Spain)
• Swedish Accident Investigation Board
• Aircraft Accident Investigation Bureau(Switzerland)
• Air Accidents Investigation Branch(UK)
• National Transportation Safety Board(USA)
• European Co-ordination Center for Aircraft Incident Reporting Systems(ECCAIRS)

Air safety investigators

Air safety investigators are trained and authorized to investigate aviation accidents and incidents: to research, analyse, and report their conclusions. They may be specialized in flight operations, training, aircraft structures, air traffic control, flight recorders or human factors. They are employed by government organizations responsible for aviation safety, manufacturers or unions, though only government organizations have statutory powers to investigate.

Safety improvement initiatives

The safety improvement initiatives are aviation safety partnerships between regulators, manufacturers, operators, professional unions, research organisations, and international aviation organisations to further enhance safety. Some major safety initiatives worldwide are:

• Commercial Aviation Safety Team (CAST)in the US. The Commercial Aviation Safety Team (CAST) was founded in 1998 with a goal to reduce the commercial aviation fatality rate in the United States by 80 percent by 2007.
• European Strategic Safety Initiative (ESSI).The European Strategic Safety Initiative (ESSI) is an aviation safety partnership between EASA, other regulators and the industry. The initiative objective is to further enhance safety for citizens in Europe and worldwide through safety analysis, implementation of cost effective action plans, and coordination with other safety initiatives worldwide.

After the disappearance ofMalaysia Airlines Flight 370,in June 2014, theInternational Air Transport Associationsaid it was working on implementing new measures to track aircraft in flight in real time. A special panel was considering a range of options including the production of equipment especially designed to ensure real-time tracking.

Since pilot error accounts for between one-third and 60% of aviation accidents, advances in automation and technology could replace some or all of the duties of theaircraft pilots.Automation since the 1980s has already eliminated the need forflight engineers.In complex situations with severely degraded systems, the problem-solving and judgement capability of humans is challenging to achieve with automated systems, for example the catastrophic engine failures experienced byUnited Airlines Flight 232andQantas Flight 32.However, with more accurate software modeling of aeronautic factors, test planes have beensuccessfully flownin these conditions.

While theaccidentrate is very low, to ensure they do not rise with theair transportgrowth, experts recommend creating a robust culture of collecting information from employees without blame.

Regulators

• Directorate- General of Civil Aviation, India.
• Civil Aviation Authority(United Kingdom)
• Department of Infrastructure, Transport, Regional Development and Local Government(Australia)
• European Aviation Safety Agency
• Federal Aviation Administration(United States)
  • Federal Aviation Regulations
• Irish Aviation Authority
• Transport Canada
• Directorate General of Civil Aviation(Indonesia)

See also

• Air traffic control
• Aircraft fire trainer
• Aircraft hijacking
• Airport security
• Aviation Safety Network(ASN)
• Aviation Safety Reporting System
• Ballistic parachute
• Crashworthiness
• Chicago Convention on International Civil Aviation
• Hazard analysis
• Health hazards of air travel
• IATA Operational Safety Audit
• Incident pit,conceptual model from diving for explaining incident development and recovery
• Jet Airliner Crash Data Evaluation Centre(JACDEC)
• Lasers and aviation safety
• Mid-air collision
• Pilot error
• Safety of emergency medical services flights
• Sensory illusions in aviation
• Sixty second review,a technique used by flight attendants to focus and prepare for a sudden emergency
• SKYbrary
• Swiss cheese model
• System accident
• Tombstone mentality
• Travel § Safety
• Uncontrolled decompression
• Wind shear
• Zonal safety analysis

External links

• Aviation safety network database
• 10 Plane Crashes That Changed Aviation
• Safety Behaviours – a guide for pilots(comprehensive human factors information)
• NASA Aviation Safety Reporting System (ASRS)
• Latest Aviation Safety Occurrences at the Aviation Safety Network
• Aviation Safety: Advancements Being Pursued to Improve Airliner Cabin Occupant Safety and Health, 2003