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Weather

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Revision as of 15:35, 4 January 2011 by Anonymous (talk) (Description)
Article Information
Category: Weather Weather
Content source: SKYbrary About SKYbrary
Content control: EUROCONTROL EUROCONTROL

Wx

Description

Of all things which influence the safety of flight, the weather - the characteristics and behaviour of the Earth’s atmosphere - is without doubt the most powerful.

The following can have a direct and indirect influence on flight safety:

  • Turbulence associated with convective activity (for example, thunderstorms), terrain (for example, the movement of air masses over mountains), jet streams and the interaction between air masses, can cause structural damage to aircraft.
  • Icing: Ice Formation on Aircraft can alter the aerodynamic characteristics of an aircraft and cause damage to or loss of function of the engines and seriously affect the performance of an aircraft. The article Aircraft and In Flight Icing Risks discusses the commonly-encountered issues whilst High Level Ice Crystal Icing: Effects on Engines of turbine engines is a recently-identified and improperly understood phenomenon which occurs outside the normal icing envelope. Ice may form on aircraft whilst they are on the ground prior to flight and this must be removed and any further accretion on the airframe prevented by the Aircraft Ground De/Anti-Icing so that any aircraft is free of ice deposits at the point at which it gets airborne.
  • Reduced visibility, associated with cloud, mist, fog, or sand storms, can make safe flight difficult or even impossible, even with the help of technology (Instrument Landing System (ILS), weather radar, synthetic vision systems, etc)
  • Surface contamination; standing water, ice, or snow on take-off, landing and manoeuvre surfaces.
  • Wind Velocity; near the ground, the influence of wind on directional control and Cross Wind Landings or take-offs can, if not dealt with effectively, lead to Runway Excursion.
  • Precipitation; for example rain, hail, and snow affect aerodynamics and visibility.
  • Lightning; a lightning strike can be very distressing to passengers (and crew!) but physical damage to an aircraft only very rarely threaten the safety of an aircraft, usually a small one. Of greater concern is the effect a lightning strike can have on avionics, particularly compass and air data systems, and in case of rear mounted jet engines, the potential for the transient airflow disturbance associated with lightning to cause engine shutdown on both Full Authority Digital Engine Control (FADEC) and non-FADEC engines because of their close spacing and exposure to the same airflow disturbance at the same time.

Many of the operational safety issues that are addressed within SKYbrary can be affected by weather:

There are numerous specific mitigation strategies to maintain the safety of flight in certain types of weather. These may be technical, procedural, or navigation based, or all three, and it may be appropriate to re-route, delay or cancel a flight if no satisfactory mitigation is available. A common requirement is that all those associated with the safety of flight should have an understanding of meteorology appropriate to their operational role.

Aviation Meteorology

The study of aviation meteorological theory can be divided into a number of topics:

The application of this theory is further considered:

Further Reading

  • The theme of Hindsight 7 (EUROCONTROL's Safety Magazine) was Weather and contains a number of articles discussing hazards to aviation associated with weather phenomena.
  • FAA Review of NTSB weather related accidents during the 10 year period (1994-2003)
  • Review of Aviation Accidents involving Weather Turbulence in the United States 1992-2001 (FAA 2004)
  • Safety Study: Risk Factors Associated with Weather-Related General Aviation Accidents (NTSB 2005)
  • see also FAA "Lessons Learned from Transport Airplane Accidents": Inclement Weather / Icing