Weather related aircraft accidents have become a major safety concern in the world lately. Visual rules flight to the Instrument Meteorology Conditions has attracted world attention because of high rates of the fatalities which is associated with them. Safety research aviation professionals are trying to explain mechanisms and genesis of such accidents. According to macro statistics conducted by FAA, it is approximated that seventy percent of delays in the National Airspace System is caused by adverse weather conditions. According to iapa.com, weather plays a significant role in aviation accidents and incidents. The report conducted by National Transparency Safety Board (NTSB) shows that human error is the direct cause of accidents while weather only contributes 23% of all aviation accidents. $3 billion is an estimated national cost for accident injuries and damage, delays and unexpected operating costs caused by weather impact. Weather conditions may influence incidence of aircraft accidents in several ways (iapa.com, 2010)
Errors caused by Human
- Failure to preflight
- Operations done based on imperfect systems
- Adverse weather
- Unpromising aircraft controllers
- Inadequate and poor planning
- Outside envelope development
- Flying into poor weather conditions
- Lack of proficiency during operation
- Mechanical and structural failure
- Propulsion malfunction
- Electrical system failure
- Complex designing of airplane and its components
- Fatigue and corrosion
This paper therefore observes and explores the Aircraft accidents caused by various adverse weather conditions
Thunderstorms and Other Convective Weather
Hazards associated with the convictive weather include intense up and downdrafts, thunderstorms with severe turbulence, hail, lightning, heavy precipitation, wind shear, icing, strong low-level winds, microbursts and tornadoes. National Aviation Safety Data Analysis Center (NASDAC) estimated that between the years 1989-1997, thunderstorms were the main contributing factor in two to four percent of weather related accidents. Precipitation was named as a factor in six percent of commercial air carrier accidents and 10% of general aviation accidents. The American Airlines has estimated that fifty five percent of turbulence occurrences are caused by convective weather. Convective weather poses a major problem for efficient operation of NAS. Thunderstorms and other related phenomena can slam airports, degrade capacities for the acceptance and departure and stop or hinder ground operations.
Non-convective turbulence is the main aviation hazard. All the aircraft are susceptible to turbulent motions. It can be present at different altitude and in wide range of weather conditions, occurring in clear skies as the clear air turbulence. If an aircraft enters turbulent conditions then it is vulnerable to damage. The effects of turbulence may range from jostling of aircraft which is mildly discomforting for crews and passengers to sudden accelerations which may result to serious injuries and also temporary loss of aircraft control. A carrier en route recently from Japan to United States encountered turbulence which caused the life of a passenger. Not only clear-air turbulence dangerous but it’s also has a major effect on efficiency of flight operations because of rerouting and delays of aircraft.
Aircraft on the ground during freezing periods or frozen precipitation are susceptible to build up of ice on control surfaces, propellers and engine inlets and instrument orifices. Ice and snow also causes terminal operations. Taxiways, boarding gates and runways may become unusable which may make aircrafts to crush and cause accidents to passengers because of landing problems. Operational airport capacities may sharply be reduced (Omeron, T. 1997)
Volcanic ash is a pulverized rock. It’s composed largely on the materials with melting temperature below operating temperature of the jet engine at cruise altitude. Volcanic ash in the atmosphere is accompanied by the gaseous solutions of chlorine and sulphur dioxide. The combinations of gases and pulverized rock can significantly affect performance of jet engines at cruise attitudes which may cause aircraft accidents during the night. Ash clouds are invisible particularly at night. According to statistics, there are five hundred and seventy five active volcanoes which normally contribute to fifty eruptions, resulting in fifty to seventy five danger days per year.
Delta Air Lines Flight was the airline service from the Fort Lauderdale International Airport bound for L.A International Airport in California. On August 2, 1985, the aircraft crashed while approaching the Dallas-Fort Worth International Airport killing 126 out of 152 passengers and 8 out of 11 crew members on board and one person on ground. It was caused by metrological phenomenon called microburst-induced wind shear. A thunderstorm formed directly in its path as the aircraft flew over Louisiana. Weather was poor at Dallas Airport and isolated thunderstorm developed at around DFW. The copilot and captain heard the storm but decided to continue the journey through it which led to the aircraft caught up in the microburst. Investigations were done and it was found out that the cause of the crash was attributed by pilot error together with extreme weather condition associated with induced microburst wind shear (Mark Wiggins 2011)
According to Research Council (1997), the weather condition at Dallas was bad and a thunderstorm was continuing forming. It was found difficult to detect the storms since they contained large cluster of white clouds. At the storm, a microburst had formed which wasn’t detected. A microburst is the column of sinking air which produces erratic winds and damaging on the ground. Abrupt changes in the wind direction and speed is called wind shear. The microburst has got the strength of tornado but does not have a funnel cloud of converging winds.
The cause in fatal weather accidents is being described as a scenario where a pilot initiated attempt Visual Flight rules flight into the instrumental conditions. Two point five percent of 14,000, GA accidents involved VFL flight into Instrumental meteorological Conditions. In the past decades, researchers have attempted to understand the reasons why VFR pilots have continued to fly to adverse weather conditions and what can be done to reduce weather related accidents. The dynamics of weather related aviations can simply be summarized in three stages. The preflight factors/conditions encompasses issues of pre-flight planning like route selection, weight and balance considerations, weather briefing and reports, besides pilots features like experience, self-confidence and psycho-physiological state. Organizational and social pressures play a role both during and before the flight. Within the characteristics of a pilot, various studies indicate that the average GA pilot getting involved in a weather related accident is squat on total flying hours. Pilots who are involved in such accidents would be generally overconfident in their personal abilities which make them to overestimate or underestimate risks involved to handle weather conditions. In flight factors would consist of factors that provide the updated and current information of weather besides pilots’ decision making features. It’s reported that 76% of pilots are likely to continue flying internationally as compared to 24% inadvertently encounter of adverse weather conditions. Errors caused by human continue to be accountable for sixty to eighty percent of civil and military aviation accidents. Human make errors and it may be unreasonable not to commit errors (Hughes J. 2011)
The pilot error with flight operations and weather conditions are well discussed. Investigations conducted by National Transparency Safety Board for aircraft crashes in the U.S between the years 1983 and 2002 showed pilot error and supplementary factors. The presence of pilots and crash circumstances were analyzed in relations to pilot age using tests of Chi-square.
Effects of Weather Aviation
The main priority of every civilian aviation system is to make sure every passenger is protected. If we look at statistics, weather is considered as the main cause of aircraft accidents. The CAA in the U.K showed that weather as a causal factor in thirty out of two hundred and six fixed wing accidents in 1977.
Passengers discomfort results from sudden height loss by airplanes moving in a high speed. When the unpredictable wind variation occurs near the landing ground, a hard landing may erupt leading to occurrence of an accident with the attendant passenger discomfort.
Flight schedules are well arranged using general routes and aircraft but delays often propagate even to those areas not affected by weather. Most time schedules are affected by weather conditions according a research conducted by the United States Federal Aviation Administration. In the year 1975 a total of 31672 flights were delayed because of weather conditions.
There is utmost emphasis on efficient utilization resources. Weather affects adversely on efficient utilization of resources. The major indicators of aviation systems on operating efficiency are traffic capabilities handling of the airports, air corridors and average fraction of time that the individual aircraft remains in operation.
Human factors consisting of pilot error are potential danger and also the most usual factor of the aviation crashes. A lot of progresses considering human factors in improving aviation safety have been made since the end of World War 2 by people like Alphonse Chapanis and Paul Fitts. The development of pilot checklist has been put in progress since the Delta 191 accident happened. Error caused by pilots and the improper communication are factors caused by collision of aircraft. The ability of flight crew to preserve situational awareness is critically in air safety of human factor. Training of human factor is available to all aviation pilots and it is usually referred as single pilot resource management. Failure of pilots properly monitors flight instruments resulted in Delta 191 accident crash in 1985 where they had storm but continued with the journey which led to occurrence of the accident. Also the crash of Eastern Airlines Flight 40 in the year 1972 which was caused by the error between takeoff and landing had catastrophic effects (Anaesth, J. 1987)
Human error contributes to more than seventy percent of commercial airplane accidents. It has also become major concerns maintenance of aircrafts and air traffic management. 25 years after the Delta 191 crash, the same mistake will not occur again. Aircraft control will see intensifying cell on the Terminal Doppler Weather Radar and also system of on-board wind detection would be used to alert pilots to a direction of strong wind shear. Better pilot instructions and new technologies in handling shear wind are direct results of the Delta 191’s crash. Federal Aviation Administration, researchers and tragedy galvanized NASA are working together to make sure that flying in bad weather situations is safer. According to deputy director of NASA on aeronautics research, David Hilton says that the microburst has extensively modeled and it was a strong event has ever happened in the whole world. He also explains that microburst today can be easily detected.
Weather conditions have been a major influence of air craft accidents lately. Aircrafts have been directly impacted by bad weather more so when hit by lightning storms, engine malfunctions due to ice or bouncing about in the surface as a result of turbulence. Convective hazards and wind shear are also likely to draw aircrafts to an off course, something which can lead collision with other aircrafts. Aircrafts shells are also easily damaged by hailstorms therefore altering the planes aerodynamic properties. As well, during sharp electrical storms, the pilot can be temporarily blinded and cause an accident. As a result of excessive ingestion of water by the engine can lead to “engine flame out”. Indirectly, aircraft accidents can be precipitated by weather conditions. As a result of adverse weather conditions, aircraft pilots do try to fly out of their normal ways to avoid conditions like storms. This is very dangerous due to facts that a plane may sometimes reduce its fuel level. During hazy conditions, aircrafts do lose their fuel therefore subjecting it into jeopardy state. Hazy conditions leads to the pilots unclear focusing and disorientation, a possibility of accidents occurrence. However, there are paramount measures which if applied properly; they can help reduce the number of aircraft accidents which are caused by poor weather conditions. In order to guarantee the aircrafts safety, the pilot should: Make adequate preparations before flying – A pilot who hops into an aircraft and takes off invite a lot of potential dangers (Goh & Wiegman. 1997)
Before the flight, a pilot should take the responsibility of making some imperative investigations concerning the flight. For instance, he should figure out and confirm the route of the flight. That will enable him or her to estimate the amount of fuel and time needed for the flight such that in case of any delays by the adversity of weather conditions, he will be safe. It is also the obligation of the pilot in charge to investigate and be updated on the current forecasted weather conditions, or else, the ramification of ignoring it may bring a very disastrous outcome which might be regretted forever. Sometimes, aircrafts may encounter bad weather or even run out of fuel. Further, without a clear plan of the flight on file, an accident in which the aircraft might have survived might turn out to bring fatalities. Some pilots are known to stretch weather limits in their will so as to quickly reach their destinations. Some pilots do invite troubles when they press on flying into adverse weather conditions where they are not equipped or conversant to fly through. Such conditions are during thunderstorms, the pilot’s poor visibility, and icing. Due to spiral instability mode with most of the aircrafts, VFR pilots who lose references abruptly to horizon can be in serious trouble. Pilots should avoid forcing their way into adverse weather conditions and take necessary precautions in case of emergencies (McCormick, B. 2003)
Plane crash is a worst thing that can happen in this world. Airline industries should prepare well when they face such situations. The airline industry also has a lot of lessons to teach other industries on crisis managers. Once the airline crash many people fear travelling on air because they think that it is not a good idea using it. This may cause airlines to suffer from cancellations of flights and decline in bookings. People only see one accident as too many. A key concern in airline industry now is safety. Due to technological advancement and investigations from dedicated safety professionals, has made the airline industry’s records concerning safety to be high. Several agencies like Federal Aviation Administration and National Transportation Safety Board has contributed to the safety of US airlines since the Delta 191 accident. Since accidents can’t be predicted, some complex issues may develop when the accident occur. Airline must communicate to victims or their families, the public, the media, other airlines, government agencies, officers, and future customers for it to survive the crisis. It also should get the situation under control.
List of references:
Anaesth, J. (1987): Human Factors in Accidents. Retrieved on 1st April 1, 2011 from http://bja.oxfordjournals.org/content/59/7/856.extract
Goh & Wiegman (1997): Visual Flight Rules (VFR) Flight into Instrument Meteorological Conditions (IMC): A Review of the Accident Data. Retrieved from http://www.faa.gov/library/online_libraries/aerospace_medicine/sd/media/Goh.pdf
Hughes J. (2011): Work domain analysis for air traffic controller weather displays. Elsevier Ltd.
iapa.com, (2010): 25 Years Later: The Lessons Learned from a Tragic Accident. Retrieved 1st April 2010 from http://www.iapa.com/index.cfm/travel/blog.article/blog/community/art/25-year-later-the-lessons-learned-from-a-tragic-event.
Mark Wiggins (2011): Weatherwise: Evaluation of a Cue-Based Training Approach for the Recognition of Deteriorating Weather Conditions during Flight.
McCormick, B. (2003): Aircraft accident reconstruction and litigation. Tucson: Lawyers & Judges Publishing Company, Inc.
National Research Council (1995): Aviation weather services: a call for federal leadership and action. U.S.A. National Academies Press.
Omeron, T. (1997): The Relationship between Aircraft Icing and Synoptic-Scale Weather Conditions.