A take-off warning system or TOWS is a set of warning signals required on most commercial aircraft, designed to alert the pilots of potentially-dangerous errors in an aircraft's take-off configuration.
There are numerous systems on board an aircraft that must be set in the proper configuration to allow it to take off safely. Prior to every flight, the flight officers use checklists to verify that each of the many systems is operating and has been configured correctly. Due to the inevitability of
human error
Human error refers to something having been done that was " not intended by the actor; not desired by a set of rules or an external observer; or that led the task or system outside its acceptable limits".Senders, J.W. and Moray, N.P. (1991) Human ...
, even the checklist procedure can lead to failures to properly configure the aircraft.
Several improper configurations can leave an aircraft completely unable to become airborne—these conditions can easily result in fatal
hull loss
A hull loss is an aviation accident that catastrophically damages the aircraft beyond economical repair, resulting in a total loss. The term also applies to situations in which the aircraft is missing, the search for their wreckage is terminated ...
accidents. In order to reduce this, all major nations now mandate something similar to the US requirement that on (nearly) "all airplanes with a maximum weight more than 6,000 pounds and all jets
..a takeoff warning system must be installed". This system must meet the following requirements:
(a) The system must provide to the pilots an aural warning that is automatically activated during the initial portion of the takeoff roll if the airplane is in a configuration that would not allow a safe takeoff. The warning must continue until—
:(1) The configuration is changed to allow safe takeoff, or
:(2) Action is taken by the pilot to abandon the takeoff roll.
(b) The means used to activate the system must function properly for all authorized takeoff power settings and procedures and throughout the ranges of takeoff weights, altitudes, and temperatures for which certification is requested.[ ]
TOWS is designed to sound a warning for numerous other dangerous errors in the take-off configuration, such as the flaps and slats not being extended when the throttles are opened while the aircraft is on the ground. The alert is typically in the form of an audible warning horn accompanied by a voice message that indicates the nature of the configuration error.
See also
A number of aircraft disasters due to improper configuration have happened in spite of the presence of a functional take-off warning system:
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Delta Air Lines Flight 1141
Delta Air Lines Flight 1141 was a scheduled domestic passenger flight between Dallas/Fort Worth, Texas and Salt Lake City, Utah. On August 31, 1988, the flight, using a Boeing 727-200 series aircraft, crashed during takeoff, resulting in 14 deat ...
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LAPA Flight 3142
LAPA Flight 3142 was a scheduled Buenos Aires– Córdoba flight operated by the Argentine airline Líneas Aéreas Privadas Argentinas. The flight was operated with a Boeing 737-204C, registration LV-WRZ, that crashed on 31 August 1999 at 20:5 ...
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Lufthansa Flight 540
Lufthansa Flight 540 was a scheduled commercial flight for Lufthansa, serving the Frankfurt–Nairobi–Johannesburg route.
On 20 November 1974, the Boeing 747-130 that was operating as Flight 540 was carrying 157 people (140 passenge ...
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Mandala Airlines Flight 91
Mandala Airlines Flight 091 was a scheduled domestic passenger flight from Medan to Jakarta, operated by Mandala Airlines with a Boeing 737-200Adv. On September 5, 2005 at 10:15 a.m. WIB (UTC+7), the aircraft stalled and crashed into a heavily ...
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Northwest Airlines Flight 255
On August 16, 1987 a McDonnell Douglas MD-80#MD-82, McDonnell Douglas MD-82, operating as Northwest Airlines Flight 255, crashed shortly after takeoff from Detroit Metropolitan Airport, about 8:46 pm Eastern Time Zone, EDT (00:46 UTC Augus ...
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Spanair Flight 5022
Spanair Flight 5022 was a scheduled domestic passenger flight from Barcelona–El Prat Airport to Gran Canaria Airport, Spain, via Madrid–Barajas Airport that crashed just after take-off from runway 36L at Madrid Airport at 14:24 CES ...
References
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Avionics
Warning systems