Accidents in the aviation industry can occur due to many factors. An aviation accident is the worst nightmare of every pilot or passenger that has ever ridden in an aircraft. Although air travel is one of the safest forms of transportation, accidents do happen with dramatic and terrifying results. The causes of these aviation accidents vary greatly depending on specific circumstances and problems that may develop during the flight process. Weather is one of the factors that can influence an aircraft accident in a number of ways. There are several weather factors that cause and contributed to aircraft accidents.
An aircraft can become directly impacted by weather when they are struck by lightning in storms, blown off course, incur malfunctions due to icing up of engine and wing parts, or are bounced about in the air by turbulence. Even if the act of weather itself doesn’t cause an accident the distraction of the weather could cause an accident. Introduction Weather plays a significant role in a great number of aircraft accidents and incidents. Weather is one major issue that is not within the control of technology or aviation system planners.
Statistics has indicated that 28% of general aviation accidents involved adverse weather conditions (PlaneCrashInfo). Weather conditions can cause aircraft accidents indirectly as well. An aircraft that encounters adverse weather often has to travel out of its way to miss flying through a storm, and this can dangerously reduce its fuel level. Furthermore, adverse weather conditions such as haze can cause problems with visibility or disorientation can lead to an accident. Weather conditions can also affect the performance of an aircraft, like when parts are iced and cease to function.
In most cases, adverse weather can be a distraction on land and in the air. Distractions are often the cause to many accidents. Weather conditions influence the frequency of aircraft accidents in many ways. Some of the weather factors that cause or contribute to weather related accidents are icing, turbulence, wind shear, thunderstorms, and haze. Weather Conditions Icing According to the AOPA Safety Advisor when temperature is 0 degree Celsius or less and moisture is present. Ice can form on an aircraft structure (Aircraft Icing). The most significant hazard of structural icing is the disruption of airflow over the aircraft surface.
What is meant by the disruption of airflow is when airflow reduces lift and increase drag. This causes the aircraft to stall at a lower angle of attack and at a higher speed than normal. Ice can also form in the engine intake, blocking the flow of air to the engine, which can cause engine failure. In-flight icing is not only dangerous, but also has a major impact on the efficiency of flight operations. Icing poses danger to aircraft in several ways. The structural icing on wings and control surface increase aircraft weight, degrades lift, generates false instrument reading, and compromise control of the aircraft.
Mechanical icing in carburetors, engine air intakes, and fuel cells impairs engine performance, leading to reduction of power. Here is an instance where icing caused an aircraft accident. According to Aviation Knowledge website on October 31, 1994, an aircraft departs from Indianapolis going to Chicago O’Hare for a regular flight taking one hour five minutes. When the airplane was about 50nm from Chicago it was placed in a holding pattern at 10,000 feet because of heavy traffic. Thirty minutes later the plane crashes in a field close to Roselawn, Indiana.
The 68 passengers and crew died, while holding, the plane encountered freezing rain. When they were clear to descend to 8,000 feet, they were ordered to hold again. While in the holding pattern a warning sound indicating an over speed warning due to extended flaps was heard. Soon after the pilot took action, an uncommand roll excursion occurred, which disabled the auto pilot. The crew encounters another roll after recovering from the first one, and shortly after the plane crashed (American Eagle Flight 4184). Turbulence Turbulence is the movement of unstable air and can be used by many factors.
Accidents caused by turbulence are contributed due to turbulence is 75% of all weather related accidents and incident (PBS). Turbulence is a major aviation hazard, and all aircrafts are vulnerable to turbulent motions. It can be present at any altitude and in a wide range of weather conditions, often occurring in relatively clear skies as clear-air turbulence. Any aircraft entering turbulent conditions is vulnerable to damages. The effects of turbulence can range from a bumping of the aircraft that can be discomforting for passengers and crew.
It can also cause sudden accelerations that can result in serious injury or temporary loss of aircraft control. Clear-air turbulence is not only dangerous, it also has a major impact on the efficiency of flight operations due to rerouting and delays of aircraft. According to the FAA, “From 1980 through 2008 U. S. air carriers had 234 turbulence accidents, resulting in 298 serious injuries and three fatalities” (Turbulence: Staying Safe). In 1997, a Japanese passenger on a United Airlines flight from Tokyo to Honolulu was jolted out of her seat when the plane encountered turbulence.
She suffered fatal injuries when she hit the armrest on the way back down. The passenger was not wearing a seatbelt; according to the NTSB accident brief (Brief of Accident). Wind Shear Wind shear is a sudden drastic change in wind speed and direction that generally is associated with convective activity (Adverse Weather Conditions). An encounter with wind shear can make it difficult or impossible to maintain control of an aircraft. Since, wind shears are so hazardous, some airports have low-level wind shear alert systems to warn pilots of the presence of wind shear. Wind shear is another weather phenomenon that can occur even in clear air.
There is a particular type of wind shear known as microbursts, which produce strong wind shears (Adverse Weather Operations). Microbursts are short down drafts that move outward as they rush toward the ground creating increasing headwinds over the wings of an oncoming aircraft. This will result in spike airspeed that causes the plane to lift. The wind shear quickly becomes a downdraft and then a tailwind as the plane pass through it. This reduces the airspeed over the wings and eliminates extra lift and speed, which make the plane prone to sudden loss of airspeed and altitude.
If a pilot can add power to the engines, they may be able to escape the microburst, but if not, their only options maybe to crash (Adverse Weather Operations). According to Chris Kilroy, as Delta Flight 191 approached for landing at Dallas Fort Worth airport, a thunderstorm lurked near the runway. Lightning flashed around the plane at 800 feet, and the aircraft encountered a microburst wind shear. It caused the plane to lose 54 knots of airspeed in a few seconds. Sinking rapidly, the aircraft hit the ground about a mile short of the runway and bounced across a highway, crushing a vehicle and killing the driver.
The plane then veered left and crashed into two huge airport water tanks. On board, 134 of 163 people were killed (Solutions for Safer Skies). Thunderstorms Thunderstorms carry with them a variety of weather related risks to an aircraft. Thunderstorms occurring as the result of surface heating are known as air mass thunderstorms. Those occurring as the result of weather systems are known as steady state thunderstorm. The hazards that are associated with thunderstorms include hail, tornadoes, wind shear, icing, and turbulence (Thunderstorms and ATC).
Thunderstorms and related phenomena can close airports, degrade airport capacities for acceptance and departure, and hinder or stop ground operations. Thunderstorm hazards en route can lead to rerouting and diversions that result in excess operating costs and lost passenger time. Icing occurs when updrafts carry large drops of super cooled liquid water that freezes upon impact with the aircraft (Thompson, 2009). The most dangerous icing condition is created by freezing rain, where at the impact of rain on the airframe at subzero temperatures, the rain freezes and glaze ice accumulates rapidly (Thunderstorms and ATC).
The effects of icing on the aircraft can be severe. Lightning is always a threat in thunderstorms, although airplanes are often struck by lightning, it is estimated that the odds are that each airliner in the US will be hit by lightning once each year (Thompson, 2009). It has been many years since lightning has caused an airplane to crash, primarily because airplanes are constructed of aluminum, which conducts electricity very well (Thunderstorms and ATC). When lightning hits an airplane, the electricity flows along the airplane’s skin into the air.
The one danger is that the pilot could be temporarily blinded, but this lasts only a few seconds. The danger of fuel tanks igniting has been reduced by built in systems that protect against such combustion (Thompson, 2009). Lightning can damage the electronic components that help the pilot fly the plane, but these too have built in protective systems. Another element of thunderstorms that poses a threat to aircrafts is damaging hail. Hail can cause severe damage to an aircraft whether it is in air or on the ground. When updrafts are strong in a hunderstorm, hail can be suspended in the air circulated up and down through super cooled droplets of water and particles of ice, growing larger and larger, until they fall from the storm cloud (Thunderstorms and ATC). Hail can grow surprisingly large while it is circulating, and the impact of golf ball sized or larger hail at high speeds is quite damaging to an aircraft’s fuselage and windshield. Hail that is ingested by a jet engine can cause serious internal damage and possibly engine flameout (Thompson, 2009).
Precipitation is defined as any type of water particles that forms in the atmosphere and then falls to the ground. The forms of precipitation include drizzle, rain, snow, and hail. Precipitation can affect the safety of flight by reducing visibility, affecting aircraft performance, and produce icing conditions (Pilot’s Handbook of Aeronautical). Thunderstorm can generate very heavy precipitation, which can reduce in flight and on ground visibility as well as building up static electricity on the aircraft that can interfere with radio transmission.
Also, the wet and possibly flooded runways can reduce stopping ability upon landing and decrease steering control on the ground (Thunderstorms and ATC). Heavy precipitation is far more common in aircraft related accidents. On June 01, 1999 American Airlines Flight 1420 from Dallas Fort Worth to Little Rock Arkansas crashed after it overran its landing. The aircraft was a McDonnell Douglas DC-9-82 (MD-82). The crash resulted in the aircraft captain and ten passengers losing their lives, the first officer, flight attendants and 105 passengers receiving serious injuries and 24 passengers escaping without injury.
Air traffic controller at Little Rock airport informed the crew of American Airlines Flight 1420 of rapidly deteriorating weather, including two wind shear alerts on final approach, before the aircraft tried to land and crashed off the end of the runway (NTSB, 2001). A violent thunderstorm was just rumbling onto the northwest edge of the airport and crosswinds with gusts up to 51 mph were buffeting the runway as the landing began at the end of a bumpy flight from Dallas-Fort Worth to Little Rock. Conclusion The role of weather is very significant when it comes to aviation and its effect on accidents and incidents.
While the National Transportation Safety Board reports most commonly find that human error is the direct cause of accident, weather is a primary contributing factor in a number of aviation accidents. Weather conditions have a very substantial impact on the aircraft. The adverse weather is frequently implicated either directly or indirectly in aircraft accidents. Even though modern aircrafts are built with weather related safeguards, they are still subject to the weather that might be encountered on the ground and in the air. Therefore, weather is a significant factor in aircraft accidents.
Adverse Weather Operations. Wind Shear Awareness. Retrieved from http://www. airbus. com/fileadmin/media_gallery/files/safety_library_items/AirbusSafetyLib_-FLT_OPS-ADV_WX-SEQ02. pdf Aviation Knowledge. American Eagle Flight 4184 Retrieved from http://aviationknowledge. wikidot. com/asi:american-eagle-flight-4184 Brief of Accident. National Transportation Safety Board. Retrieved from http://www. skybrary. aero/bookshelf/books/368. pdf FAA Pilot’s Handbook of Aeronautical Knowledge, FAA-H-8083-25A, 2008. Retrieved from http://www.aa.gov/library/manuals/aviation/pilot_handbook/media/FAA-H-8083-25A. pdf Federal Aviation Administration. Turbulence: Staying Safe. Retrieved from https://www. faa. gov/passengers/fly_safe/turbulence/ Kilroy, Chris. Special Report: Delta Air Lines Flight 191. Retrieved from http://www. airdisaster. com/special/special-dl191. shtml Marder, Jenny. (August 3, 2011). Airplane Turbulence: Is It Dangerous?. Retrieved from http://www. pbs. org/newshour/rundown/2011/08/airplane-turbulence-how-dangerous-is-it. html NTSB (1996).
Aircraft accident report: In-flight icing encounter and loss of control of Simmons airlines, d. b. a American eagle flight 4186 Avions de Transport Regionale (ATR) model 72-212, N401AM, Roselawn, Indiana, October 31, 1994. Washington, D. C : NTSB. Retrieved from http://www. ntsb. gov/doclib/reports/1996/AAR9602. pdf NTSB. Aircraft Accident Report: Runway Overrun During Landing, American Airlines Flight 1420, Mcdonnell Douglas Md-82, N215aa, Little Rock, Arkansas, June 1, 1999, Washington, D. C: NTSB. Retrieved from http://www. ntsb. gov/doclib/reports/2001/AAR0102. pdf Polvinen, Juhani.