Weather-Related General Aviation Accidents

Weather-related general aviation accidents are an increasing safety concern around the world. The subject has received a lot of attention due to the high rate of fatalities associated with it. Some of the weather hazards include turbulence, snowfall, lighting, and wind. Accurate and timely weather information is a necessity as it ensures that the pilots are well informed on the expected weather conditions before takeoff. Also, some flights may be delayed or cancelled due to these extreme weather conditions (Fultz 2016, 300).  Since the obtaining of accurate and timely weather forecasts is costly, some pilots experience difficulties when flying since they lack a clear mental picture of what to expect if they have not been informed about the weather.

Table of Contents

Introduction. 3

Cessna F 172 P. 4

Accident description. 4

Effects of snowfall 4

Cessna 182P. 5

Accident description. 5

Effects of severe mountain wave turbulence. 6

Conclusion. 6

Introduction

It is vital to identify and clarify any circumstances and sources of an aircraft accident. The practice will aid in avoiding the occurrence of similar accidents in the future. Bad weather has been found to be among the leading causes of aviation accidents. Aviation operations are delayed by extreme weather conditions like thunderstorms and fog. In some instances, aircraft are deiced before departure and sometimes coated with a fluid to prevent the accumulation of snow or ice onto the plane (Fultz 2016, 301). When there is lightning, handlers and fuelers on the ground are unable to do their work. The rules allow the workers to be outside for a brief time when the temperatures are too low.

Companies such as the Air Traffic Control slow departing and arriving aircraft after cloud ceilings have reduced. The presence of surface winds may lead to low acceptance rate since the plane will require bigger spacing. Low-level winds may lead to cessation of landings and takeoffs. In passenger-carrying aircraft, the primary concern is turbulence. Thunderstorms may also interrupt with the air routes for several miles. Some plane is forced to reroute due to volcanic ash that is harmful to aircraft engines (Shappell 2017, 75). The main effects of weather in aviation are the safety and efficiency of the operations. Airlines depend on accurate weather information to ensure safety and integrity in flight schedules.

Airlines use several sources to come up with accurate weather information. The causes are expected to provide information on the location of lighting, the onset of snow or ice, temperature and pressure data, and thunderstorms. The report should be displayed in the airport operation offices and the flight dispatch (Shappell 2017, 75). Unfortunately, it is costly for airlines to acquire accurate weather information and forecasts. Airlines are expected to have their meteorologists; if not, they should have a contract with a weather forecast vendor. In this paper, two weather-related aviation accidents and their causes will be discussed.

Cessna F 172 P

Accident description

Cessna F 172 P was involved in an accident on 2nd January 2010  at around 1530 UTC. The accident occurred off EBUL airfield. It was a private flight where the pilot was the owner of the plane. The aeroplane took off from Ursel airfield at 1500 UTC with only two people. 20 minutes later, the meteorological conditions worsened rapidly due to a severe snowfall. At 40 minute past 3.00pm, the airfield staff tried to contact the aircraft with no success. After approaching nearby airfields, it was clear that the aeroplane had gone missing (Rasmussen 2012, 813). A military SAR helicopter and a Federal Police helicopter were used in the search. The wreckage was found at 2100 UTC near the aircraft with both occupants fatally injured.

            According to a witness, the sound of the aeroplane engine increasing was heard followed by the cracking of trees at 1530 UTC. The fuselage of the aeroplane was found lying upside down and was still attached to the engine at a 75-degree angle. The left wing was separated from the aircraft and was approximately 4 metres behind the fuselage. It is reported that several local flights were made on that day since the weather conditions were favourable. The rapid weather change forced the aeroplanes to land in the nearest airfields. It was however not the case for Cessna F 172 P.

Effects of snowfall

Presence of snowfall significantly reduces visibility. For Cessna F 172 P, the pilot’s visibility was less than 0.25 miles. In such a case, the pilot is expected to divert into the nearest airfield. When visibility is significantly reduced by snowfall, the acceptance rates for aircraft also decrease (Kocin 2013, 42). In such cases, planes are expected to use alternative airfields. Snow accumulation may also affect airport activities, and some runways may be closed. Most snow covered areas may result in a low light optical illusion on pilots. When this happens, the pilot may lose depth-of-field and experience vision contrast. A flat light makes it difficult for pilots to distinguish distances as well as closure rates.

            The condition gives pilots an illusion that they may be descending or ascending yet they are flying at the required level. Pilots need proper planning and training to operate an aircraft in such conditions. In case the pilot is uneducated on this, it would be wise to boycott the flight and reschedule it (Kocin 2013, 42). When an apparatus is surrounded by blowing snow, it may lead to a whiteout. In this situation, a pilot is unable to see any shadows, horizon or clouds thus lacking any visual reference to depend on.  A whiteout may start as a flat light situation before worsening.

Cessna 182P

Accident description

Cessna 182P was involved in an accident on 22nd August 2013 at 1101 UTC. The aircraft was travelling from Polokwane aerodrome (FAPP) Limpopo province to Kitty Hawk aerodrome (FAKT) Gauteng province. It was a private aircraft with two occupants on board. Both of the occupants were pilots. The wreckage was recovered at Blyde River Canyon National park Mountains at an elevated ground of about 5200 feet above mean sea levels (Belcastro 2010, 8004). On that day, there were no clouds reported, the direction of the wind was 140 degrees, and the speed was 10 knots.

            Humidity was about 34%, and the dew point temperature was 8 degrees Celsius. Both occupants died. On a fateful day, the two certified pilots departed Polokwane on an African self-safari bush adventure flight to Kitty Hawk. After the departure, the aircraft was seen executing a 180 degrees turn to the left to avoid the rising terrain and ended up colliding in high ground. The investigation carried out showed that the aircraft experienced severe mountain wave turbulence and down flowing air in the area.

Effects of severe mountain wave turbulence

The wavelength usually depends on several factors including the height of the high ground, the speed of the wind, and how unstable the atmosphere is. Mountain waves typically lead to severe turbulence, powerful vertical currents, and icing. One of the main effects is the loss of control. The vertical currents in the waves pose a challenge for an aircraft to maintain and en route altitude (Williams 2014, 60). As a result, there are level busts which lead to extreme fluctuations in airspeed. A pilot is likely to lose control if there is a risk of terrain contact or an emergency landing if the crew does not respond fast enough to a downdraft. 

When an aircraft encounters turbulence, it may suffer extreme structural damage. If the conditions are severe, it may lead to a plane break up. In moderate turmoil, the loss is usually on the fittings within the aircraft. If it was unexpected, it might injure the crew and the passengers walking around. Some icing might be experienced in the clouds which are connected with the wave peaks (Williams 2014, 60). When an aircraft approaches a mountain ridge, it is advisable that it crosses at an angle of around 30 to 45 degrees if it is heading upwind towards it. In this way, it will escape any downdrafts.

Conclusion

Every airport is expected to have a meteorological team that will provide accurate weather forecasts on time. In this way, pilots will be well informed and thus be aware of what to expect. Furthermore, airlines should only allow pilots who know how to fly in the snow to do so. It will reduce accidents that would have been caused as a result of snowfalls. It is essential for airport and airlines to remind their pilots the necessity of landing at close airports in case there is a snowfall. In an example of the severe downdraft, a pilot is advised to use full power and fly upwards at the best rate climb speed for the altitude.

Bibliography

Fultz, A.J. and Ashley, W.S., 2016. Fatal weather-related general aviation accidents in the United States. Physical Geography, 37(5), pp.291-312.

Shappell, S., Detwiler, C., Holcomb, K., Hackworth, C., Boquet, A. and Wiegmann, D.A., 2017. Human error and commercial aviation accidents: an analysis using the human factors analysis and classification system. In Human Error in Aviation (pp. 73-88). Routledge.

Kocin, P. and Uccellini, L. eds., 2013. Northeast Snowstorms: Volume 1 and (Vol. 2). Springer Science & Business Media.

Rasmussen, Roy, Bruce Baker, John Kochendorfer, Tilden Meyers, Scott Landolt, Alexandre P. Fischer, Jenny Black et al. “How well are we measuring snow: The NOAA/FAA/NCAR winter precipitation test bed.” Bulletin of the American Meteorological Society 93, no. 6 (2012): 811-829.

Williams, J.K., 2014. Using random forests to diagnose aviation turbulence. Machine learning, 95(1), pp.51-70.

Belcastro, C. and Foster, J., 2010, August. Aircraft loss-of-control accident analysis. In AIAA Guidance, Navigation, and Control Conference (p. 8004).