Система Пито-Статического Давления в Авиации: Принцип Работы и Безопасность

System of pressure sensitive instruments used to determine an aircraft's speed, altitude, etc. A pitot–static system is a system of pressure sensitive instruments that is most often used in aviation to determine an aircraft's airspeed, Mach number, altitude, and altitude trend. A pitot–static system generally consists of a pitot tube, a static port, and the pitot–static instruments. Other instruments that might be connected are air data computers, flight data recorders, altitude encoders, cabin pressurization controllers, and various airspeed switches. Errors in pitot–static system readings can be extremely dangerous as the information obtained from the pitot static system, such as altitude, is potentially safety critical. Several commercial airline disasters have been traced to a failure of the pitot–static system. The Code of Federal Regulations (CFRs) require pitot–static systems installed in US registered aircraft to be tested and inspected every 24 calendar months.

The pitot–static system of instruments uses the principle of air pressure gradient. It works by measuring pressures or pressure differences and using these values to assess the speed and altitude.

The pressure altimeter, also known as the barometric altimeter, is used to determine changes in air pressure that occur as the aircraft's altitude changes. The vertical speed specifically shows the rate of climb or the rate of descent, which is measured in feet per minute or meters per second. A blocked pitot tube will cause the airspeed indicator to register an increase in airspeed when the aircraft climbs, even though actual airspeed is constant. (As long as the drain hole is also blocked, as the air pressure would otherwise leak out to the atmosphere.) This is caused by the pressure in the pitot system remaining constant when the atmospheric pressure (and static pressure) are decreasing. Conversely, the airspeed indicator will show a decrease in airspeed when the aircraft descends. The pitot tube is susceptible to becoming clogged by ice, water, insects or some other obstruction. Lag error is only significant around the time when the airspeed or altitude are changing. It is not a concern for steady level flight.

1 December 1974 – Northwest Airlines Flight 6231, a Boeing 727, crashed northwest of John F. Kennedy International Airport during climb en route to Buffalo Niagara International Airport because of blockage of the pitot tubes by atmospheric icing. 6 February 1996 – Birgenair Flight 301 crashed into the sea shortly after takeoff due to incorrect readings from the airspeed indicator. The suspected cause is a blocked pitot tube (this was never confirmed, as the airplane wreck was not recovered). 2 October 1996 – Aeroperú Flight 603 crashed because of blockage of the static ports. The static ports on the left side of the aircraft had been taped over while the aircraft was being waxed and cleaned. After the job was done, the tape was not removed. February 23, 2008 – A B 2 bomber took off from Andersen Air Force Base in Guam and subsequently crashed after stalling. It was caused by moisture on the air speed sensors. 1 June 2009 – The French air safety authority BEA said that pitot tube icing was a contributing factor in the crash of Air France Flight 447.