Flight with disabled controls
Encyclopedia
Several aviation incidents and accidents have occurred in which the control surfaces of the aircraft became disabled, often due to failure of hydraulic systems or the flight control system. Other incidents have occurred where controls were not functioning correctly prior to take-off, either due to maintenance or pilot error, and controls can become inoperative from extreme weather conditions. Aircraft are not designed to be flown in such circumstances, however a small number of pilots have had some success in controlling aircraft with disabled controls.
will raise the nose, while decreasing the thrust will lower it. This control method may call for control inputs that go against the pilot's
instinct: when the aircraft is in a dive, adding thrust will raise the nose and vice versa.
Additionally, asymmetrical thrust has been used for directional control: if the left engine is idled and power is increased on the right side this will result in a yaw to the left, and vice versa. If throttle
settings allow the throttles to be shifted without affecting the total amount of power, then yaw control can be combined with pitch control. If the aircraft is yawing, then the wing on the outside of this yaw movement will go faster than the inner wing. This creates higher lift on the faster wing, resulting in a rolling movement, which helps to make a turn.
Controlling airspeed
has been shown to be very difficult with engine control only, often resulting in a fast landing. A faster than normal landing also results when the flaps
can not be extended due to loss of hydraulics.
Another challenge for pilots who were forced to fly an aircraft without functioning control surfaces was to avoid the phugoid
instability mode (a cycle in which the aircraft repeatedly climbs and then dives), which required careful use of the throttle.
Because this type of aircraft control is difficult for humans to achieve, researchers have attempted to integrate this control ability into the computers of fly-by-wire
aircraft. Early attempts to add the ability to real aircraft were not very successful, the software having been based on experiments conducted in flight simulators where jet engines are usually modelled as "perfect" devices with exactly the same thrust on each engine, a linear relationship between throttle setting and thrust, and instantaneous response to input. More modern computer systems have been updated to account for these factors, and aircraft have been successfully flown with this software installed. However, it remains a rarity on commercial aircraft.
and Captain St. Clair Streett
, the chief of the U.S. Army Air Corps Materiel Division's Flying Branch
, flew the XCO-5
experimental biplane to achieve an unofficial altitude record for aircraft carrying more than one person: 37854 feet (11,537.9 m); less than 1000 feet (304.8 m) short of the official single-person altitude record. Stevens snapped photographs of the ground below, warmed by electrically heated mittens and many layers of clothing. At that height the men measured a temperature of -78 F, cold enough to freeze the aircraft controls. When Stevens was finished with his camera, Streett found that the aircraft's controls were rendered immobile in the cold, with Streett unable to reduce throttle for descent. The aircraft's engine continued to run at the high power level necessary for maintaining high altitude. Streett contemplated diving at full power, but the XCO-5 was not built for such strong maneuvers—its wings could have sheared off. Instead, Streett waited until fuel was exhausted and the engine sputtered to a stop, after which he piloted the fragile aircraft down in a gentle glide and made a deadstick landing
. An article about the feat appeared in Popular Science
in May 1929, entitled "Stranded—Seven Miles Up!"
Control techniques
A basic means of controlling an aircraft with disabled flight controls, discovered through crew experience, is by making use of the position of the engines. If the engines are mounted under the centre of gravity, as is the case in most passenger jets, then increasing the thrustThrust
Thrust is a reaction force described quantitatively by Newton's second and third laws. When a system expels or accelerates mass in one direction the accelerated mass will cause a force of equal magnitude but opposite direction on that system....
will raise the nose, while decreasing the thrust will lower it. This control method may call for control inputs that go against the pilot's
Aviator
An aviator is a person who flies an aircraft. The first recorded use of the term was in 1887, as a variation of 'aviation', from the Latin avis , coined in 1863 by G. de la Landelle in Aviation Ou Navigation Aérienne...
instinct: when the aircraft is in a dive, adding thrust will raise the nose and vice versa.
Additionally, asymmetrical thrust has been used for directional control: if the left engine is idled and power is increased on the right side this will result in a yaw to the left, and vice versa. If throttle
Aircraft engine controls
Aircraft engine controls provide a means for the pilot to control and monitor the operation of the aircraft's powerplant. This article describes controls used with a basic internal-combustion engine driving a propeller. Some optional or more advanced configurations are described at the end of the...
settings allow the throttles to be shifted without affecting the total amount of power, then yaw control can be combined with pitch control. If the aircraft is yawing, then the wing on the outside of this yaw movement will go faster than the inner wing. This creates higher lift on the faster wing, resulting in a rolling movement, which helps to make a turn.
Controlling airspeed
Airspeed
Airspeed is the speed of an aircraft relative to the air. Among the common conventions for qualifying airspeed are: indicated airspeed , calibrated airspeed , true airspeed , equivalent airspeed and density airspeed....
has been shown to be very difficult with engine control only, often resulting in a fast landing. A faster than normal landing also results when the flaps
High-lift device
In aircraft design, high-lift devices are moving surfaces or stationary components intended to increase lift during certain flight conditions. They include common devices such as flaps and slats, as well as less common features such as leading edge extensions and blown flaps.-Purpose:Aircraft...
can not be extended due to loss of hydraulics.
Another challenge for pilots who were forced to fly an aircraft without functioning control surfaces was to avoid the phugoid
Phugoid
A phugoid or fugoid is an aircraft motion where the vehicle pitches up and climbs, and then pitches down and descends, accompanied by speeding up and slowing down as it goes "uphill" and "downhill." This is one of the basic flight dynamics modes of an aircraft , and a classic example of a positive...
instability mode (a cycle in which the aircraft repeatedly climbs and then dives), which required careful use of the throttle.
Because this type of aircraft control is difficult for humans to achieve, researchers have attempted to integrate this control ability into the computers of fly-by-wire
Fly-by-wire
Fly-by-wire is a system that replaces the conventional manual flight controls of an aircraft with an electronic interface. The movements of flight controls are converted to electronic signals transmitted by wires , and flight control computers determine how to move the actuators at each control...
aircraft. Early attempts to add the ability to real aircraft were not very successful, the software having been based on experiments conducted in flight simulators where jet engines are usually modelled as "perfect" devices with exactly the same thrust on each engine, a linear relationship between throttle setting and thrust, and instantaneous response to input. More modern computer systems have been updated to account for these factors, and aircraft have been successfully flown with this software installed. However, it remains a rarity on commercial aircraft.
Controls damaged by engine failure
- LOT Polish Airlines Flight 5055LOT Polish Airlines Flight 5055LOT Polish Airlines Flight 5055 crashed in the Kabaty Woods nature reserve on the outskirts of Warsaw on May 9, 1987. The aircraft was an Ilyushin Il-62M bearing the name Tadeusz Kościuszko...
, an Ilyushin Il-62M, on 9 May 1987. According to the Polish investigatory commission, the cause of the crash was the disintegration of an engine shaft due to faulty bearings inside engine No. 2, which seized, causing extensive heat. This in turn caused the consequent damage to engine No. 1, rapid decompression of the fuselage, and a fire in the cargo hold, as well as the loss of elevator controls and progressive electrical failures. Zygmunt Pawlaczyk decided to return to Warsaw Okecie AirportWarsaw Frederic Chopin AirportWarsaw Chopin Airport is an international airport located in the Włochy district of Warsaw, Poland. Poland's busiest airport, Warsaw Chopin handles just under 50% of the country's air passenger traffic....
using only trim tabs to control the flight of the aircraft. He lost his struggle to land about 5 km from the runway in the Kabacki Forest. All 172 passengers and 11 crew members perished. - United Airlines Flight 232United Airlines Flight 232United Airlines Flight 232 was a scheduled flight from Stapleton International Airport in Denver, Colorado, to O'Hare International Airport in Chicago, with continuing service to Philadelphia International Airport...
, a McDonnell Douglas DC-10, on 19 July 1989. A fan disk in the No. 2 engine fractured, severing most of the flight controls. Dennis FitchDennis E. FitchDennis E. "Denny" Fitch is a retired commercial airline pilot. He is best known for his critical actions as an off-duty DC-10 training captain who helped captain Al Haynes minimize loss of life on United Airlines Flight 232 when all flight controls were lost, on July 19, 1989...
, a deadheadingDeadheading (aviation)In aviation, deadheading is a term used when members of an airline's flight staff are carried free of charge but not working. This most often happens when airline crew are located in the wrong place and need to travel to take up their duties...
DC-10 instructor who had studied the case of JAL Flight 123Japan Airlines Flight 123Japan Airlines Flight 123 was a Japan Airlines domestic flight from Tokyo International Airport to Osaka International Airport on August 12, 1985. The Boeing 747-146SR that made this route, registered , suffered mechanical failures 12 minutes into the flight and 32 minutes later crashed into two...
, was able to help the pilots steer the aircraft using throttle differential. Despite the break-up of the aircraft on landing, 175 of 285 passengers and 10 of the 11 crew members survived.
Controls damaged by structural failure
- American Airlines Flight 96American Airlines Flight 96American Airlines Flight 96 was a regular McDonnell Douglas DC-10-10 flight operated by American Airlines. The flight suffered a cargo door failure on 12 June 1972 while flying over Windsor, Ontario; it is thus sometimes referred to as the Windsor incident.The rapid decompression in the cargo hold...
, a McDonnell Douglas DC-10McDonnell Douglas DC-10The McDonnell Douglas DC-10 is a three-engine widebody jet airliner manufactured by McDonnell Douglas. The DC-10 has range for medium- to long-haul flights, capable of carrying a maximum 380 passengers. Its most distinguishing feature is the two turbofan engines mounted on underwing pylons and a...
, on 12 June 1972. The failure of the rear cargo door caused an explosive decompressionExplosive decompressionUncontrolled decompression refers to an unplanned drop in the pressure of a sealed system, such as an aircraft cabin and typically results from human error, material fatigue, engineering failure or impact causing a pressure vessel to vent into its lower-pressure surroundings or fail to pressurize...
, which in turn caused the rear main cabin floor to collapse and severed flight controls. The pilots had only limited aileronAileronAilerons are hinged flight control surfaces attached to the trailing edge of the wing of a fixed-wing aircraft. The ailerons are used to control the aircraft in roll, which results in a change in heading due to the tilting of the lift vector...
s and elevatorElevator (aircraft)Elevators are flight control surfaces, usually at the rear of an aircraft, which control the aircraft's orientation by changing the pitch of the aircraft, and so also the angle of attack of the wing. In simplified terms, they make the aircraft nose-up or nose-down...
s; the rudder was jammed. The number two engine also ran down to idle at the time of decompression. The aircraft landed safely at Detroit-Metropolitan AirportDetroit Metropolitan Wayne County AirportDetroit Metropolitan Wayne County Airport , usually called Detroit Metro Airport, Metro Airport locally, or simply DTW, is a major international airport covering in Romulus, Michigan, a suburb of Detroit. It is Michigan's busiest airport....
. - Japan Airlines Flight 123Japan Airlines Flight 123Japan Airlines Flight 123 was a Japan Airlines domestic flight from Tokyo International Airport to Osaka International Airport on August 12, 1985. The Boeing 747-146SR that made this route, registered , suffered mechanical failures 12 minutes into the flight and 32 minutes later crashed into two...
, a Boeing 747Boeing 747The Boeing 747 is a wide-body commercial airliner and cargo transport, often referred to by its original nickname, Jumbo Jet, or Queen of the Skies. It is among the world's most recognizable aircraft, and was the first wide-body ever produced...
, on 12 August 1985. A faulty repair years earlier had weakened the aircraft's rear pressure bulkhead, which failed in flight. The vertical stabilizerVertical stabilizerThe vertical stabilizers, vertical stabilisers, or fins, of aircraft, missiles or bombs are typically found on the aft end of the fuselage or body, and are intended to reduce aerodynamic side slip. It is analogical to a skeg on boats and ships.On aircraft, vertical stabilizers generally point upwards...
and much of the aircraft's empennageEmpennageThe empennage , also known as the tail or tail assembly, of most aircraft gives stability to the aircraft, in a similar way to the feathers on an arrow...
was blown off during the decompression. The pilots were able to continue flying the aircraft with limited control, but after 32 minutes the aircraft crashed into a mountain, killing 520 of the 524 people aboard in the deadliest single aircraft disaster in history. - Air Transat Flight 961Air Transat Flight 961Air Transat Flight 961 was a flight from Varadero, Cuba to Quebec City, Canada on March 6, 2005. The aircraft experienced a structural failure in which the rudder detached in flight...
on 6 March 2005, catastrophic structural failure: the rudder detached from the aircraft with a loud bang. The pilots regained enough control to land the aircraft safely.
Controls damaged by explosive device/weapons
- Philippine Airlines Flight 434Philippine Airlines Flight 434Philippine Airlines Flight 434 was the route designator of a flight from Ninoy Aquino International Airport, Pasay City, the Philippines, to New Tokyo International Airport , Narita near Tokyo, Japan, with one stop at Mactan-Cebu International Airport, Cebu, the Philippines.On December 11, 1994...
, a Boeing 747Boeing 747The Boeing 747 is a wide-body commercial airliner and cargo transport, often referred to by its original nickname, Jumbo Jet, or Queen of the Skies. It is among the world's most recognizable aircraft, and was the first wide-body ever produced...
, on 11 December 1994. The hydraulics were damaged by a bomb in the passenger cabin. - DHL shootdown incident in BaghdadDHL shootdown incident in BaghdadOn 22 November 2003, shortly after takeoff from Baghdad, Iraq, an Airbus A300 cargo plane owned by European Air Transport was struck on the left wing tip by a surface-to-air missile. Severe wing damage resulted in a fire and complete loss of hydraulic flight control systems. Because outboard left...
on 22 November 2003. The Airbus A300Airbus A300The Airbus A300 is a short- to medium-range widebody jet airliner. Launched in 1972 as the world's first twin-engined widebody, it was the first product of Airbus Industrie, a consortium of European aerospace companies, wholly owned today by EADS...
DHL aircraft, hit by a surface-to-air missileSurface-to-air missileA surface-to-air missile or ground-to-air missile is a missile designed to be launched from the ground to destroy aircraft or other missiles...
, was the first jet airliner to land safely without any hydraulics using only engine controls.
Accidents involving experimental flights
Thrust vectoring control [known also as jet-steering] can prevent up to 65% of all air catastrophes, including disabled Conventional Flight Control [CFC]. A few computerized studies add thrust vectoring to extant passenger airliners, like the Boeing 727 and 747[11].Extreme cold
On October 10, 1928, U.S. Army photographer Albert William StevensAlbert William Stevens
Albert William Stevens was an officer in the United States Army Air Corps, balloonist and aerial photographer.-Biography:He was born on March 13, 1886 in Belfast, Maine....
and Captain St. Clair Streett
St. Clair Streett
St. Clair Streett , known as "Bill", was a United States Air Force major general and writer who first organized and led the Strategic Air Command . Streett served as aide to air power advocate General Billy Mitchell, and was viewed by General of the Air Force Henry H...
, the chief of the U.S. Army Air Corps Materiel Division's Flying Branch
Aeronautical Systems Center
The Aeronautical Systems Center is an Air Force product center that designs, develops and delivers dominant aerospace weapon systems and capabilities for U.S. Air Force, other U.S. military, allied and coalition-partner warfighters, in support of Air Force leadership priorities...
, flew the XCO-5
Engineering Division TP-1
|-See also:-Bibliography:...
experimental biplane to achieve an unofficial altitude record for aircraft carrying more than one person: 37854 feet (11,537.9 m); less than 1000 feet (304.8 m) short of the official single-person altitude record. Stevens snapped photographs of the ground below, warmed by electrically heated mittens and many layers of clothing. At that height the men measured a temperature of -78 F, cold enough to freeze the aircraft controls. When Stevens was finished with his camera, Streett found that the aircraft's controls were rendered immobile in the cold, with Streett unable to reduce throttle for descent. The aircraft's engine continued to run at the high power level necessary for maintaining high altitude. Streett contemplated diving at full power, but the XCO-5 was not built for such strong maneuvers—its wings could have sheared off. Instead, Streett waited until fuel was exhausted and the engine sputtered to a stop, after which he piloted the fragile aircraft down in a gentle glide and made a deadstick landing
Deadstick landing
A deadstick landing, also called a dead-stick landing is a type of forced landing when an aircraft loses all of its propulsive power and is forced to land. The term is often misunderstood, as the flight controls in the majority of aircraft are either fully or partially functional, even with no...
. An article about the feat appeared in Popular Science
Popular Science
Popular Science is an American monthly magazine founded in 1872 carrying articles for the general reader on science and technology subjects. Popular Science has won over 58 awards, including the ASME awards for its journalistic excellence in both 2003 and 2004...
in May 1929, entitled "Stranded—Seven Miles Up!"
Maintenance/pilot error
- The aircraft designer Roy ChadwickRoy ChadwickRoy Chadwick, CBE, FRAeS was an aircraft designer for Avro. Born at Marsh Hall Farm, Farnworth in Widnes, son of the mechanical engineer Charles Chadwick, he was the Chief Designer for the Avro Company and was responsible for practically all of their aeroplane designs...
was killed on 23 August 1947 during a crash on take-off of the prototype Avro Tudor 2Avro TudorAvro's Type 688 Tudor was a British piston-engined airliner based on their four-engine Lincoln bomber, itself a descendant of the famous Lancaster heavy bomber, and was Britain's first pressurised airliner...
, G-AGSU, from Woodford airfield. The accident was due to an error in an overnight servicing in which the aileronAileronAilerons are hinged flight control surfaces attached to the trailing edge of the wing of a fixed-wing aircraft. The ailerons are used to control the aircraft in roll, which results in a change in heading due to the tilting of the lift vector...
control cables were inadvertently crossed.