Loss of control (LOC) is one of the largest contributors to fatal aircraft accidents worldwide and occurs when there is an unintended departure of an aircraft from controlled flight. Contributing factors may include vehicle impairment conditions, external disturbances, vehicle upset conditions, and inappropriate crew actions or responses.
Contents
Causes
Aircraft experiencing a loss of control depart from normal flight and can reach attitudes or situations from which it is impossible for them to be recovered. Due to the certification and design processes, it is extremely rare for aircraft to experience a loss of control without extreme mishandling or a technical defect.
Contributing factors involving inappropriate pilot actions may include:
Notable accidents
Loss of control has been the cause of many air disasters some of which are listed below.
Aeroflot Flight 8641 Metal fatigue in the jackscrew of the horizontal stabilizer caused the component to fail while the plane was en route from Leningrad to Kiev, Ukraine. The crew lost control of the plane and at 10:50 crashed just south of the city of Mozyr in Belarus killing all on board. In the Aftermath of the tragedy, Authorities grounded all Yakovlev Yak-42 jets, and the planes underwent major design changes until they were deemed worthy to fly again in late 1984.
China General Aviation Flight 7552 In July 1992, a Yakovlev 42D took off from Nanjing (Nanking) and climbed to about 180 ft when it lost control and crashed into a pond, 600m past the runway and caught fire.
China Northwest Airlines Flight 2303 lost control during take-off from Xi'an, China. The aircraft, a Tupolev Tu-154 had had maintenance carried out before its flight, and the autopilot yaw-channel had been erroneously connected to the bank control, and vice versa. Additionally, this incorrect maintenance was not done in a properly approved facility. When the pilot engaged the autopilot, the aircraft began to oscillate violently. Any attempts to rectify matters only made things worse, as the plane shook itself to pieces, breaking up in midair before the crew could react, killing all on board.
Lauda Air Flight 004: On 26 May 1991 The Boeing 767-3Z9ER named Mozart left Don Mueang International Airport, Bangkok, Thailand to Vienna. When the Mozart reached thirty-two thousand feet, the crew received a visual warning indicating that a possible system failure would cause the thrust reverser on the number 1 engine to deploy in flight. Having consulted the aircraft's Quick Reference Handbook, they determined that it was "just an advisory thing" and took no action. At 23:17, the thrust reverser on the number 1 engine deployed while the plane was over mountainous jungle terrain in the border area between Suphanburi and Uthai Thani provinces, Thailand. First Officer Thurner's last recorded words were, "Oh, reverser's deployed!". The 767 stalled in mid-air and entered a spiral dive to the left, disintegrating at 4,000 feet (1,200 meters). Most of the wreckage was scattered over a remote forest area roughly 1 km² in size, at an elevation of 600 m above sea level, in what is now Phu Toei National Park, Suphanburi. The wreckage was at 14.44 degrees north and 99.26 east. The wreckage site is about three nautical miles north northeast of Phu Toey, Huay Kamin, Dan Chang District, Suphan Buri Province. Hikers arrived at the crash site and made video recordings of the wreckage.
United Airlines Flight 585: On March 3, 1991, 737-200 Flight 585 was on final approach to Colorado Springs Municipal Airport from Stapleton when it spun out of control, banking right, then rolled upside down before entering a downward spiral to the right. The aircraft disintegrated when it hit the ground All 20 passengers and 5 crew were killed.
USAir Flight 427: Three years later on September 8, 1994 another Boeing 737 spun out of control and crashed, the Boeing 737-3B7 flying the route which was registered N513AU, was approaching runway 28R of Pittsburgh International Airport, located in Findlay Township, Pennsylvania. The aircraft suddenly banked violently to the left, rolled upside down, then went into a downward spiral while rolling left. The jet then crashed near the airport; the crash killed all 127 passengers and 5 crew. The bodies of the occupants were so severely fragmented that the crash site was initially declared a biohazard by the NTSB. Both crashes were traced to a malfunction in the planes' rudder controls.
American Eagle Flight 4184: a flight from Indianapolis to Chicago using an ATR-72, was preparing for landing when the right aileron suddenly moved upward, causing the right wing to drop abruptly. The plane pitched down and went into a dive, corkscrewing about its right wing, and impacted the ground in a soybean field near Roselawn, Indiana. All 64 passengers and 4 crew members perished. Investigators determined that the crash was caused by atmospheric icing disrupting airflow over the right wing.
Alaska Airlines Flight 261: took off from Mexico en route to California. The MD-83 had been in maintenance, and the T-tail's jackscrew had not been checked as called for in the maintenance schedule. After several tries, the crew was able to unfreeze the stabilizer, and the airplane pitched downward into a dive. The pilots were able to recover and were preparing to divert to Los Angeles when the tail broke loose from its assembly. The plane pitched over again 70 degrees nose down, rolling inverted as it fell. The pilots attempted to control the aircraft while inverted to no avail; 86 seconds later the aircraft hit the Pacific Ocean nose first and broke up on impact with the water, killing everybody on board instantly.
Copa Airlines Flight 201: was preparing to land in fierce thunderstorms when, in a manner similar to the Colorado Springs crash, the plane suddenly banked sharply to the right and spiral-dived to the ground, crashing in a jungle area of the Darien Gap at the speed of 400 knots (460 miles per hour), killing all 47 passengers on board instantly. An investigation revealed that the plane's attitude indicator had failed, causing the pilots to lose track of their plane's bank angle.
Aeroflot Flight 4227: took off from Almaty International Airport en route to Simferopol Airport, the Tupolev entered an altitude of no more than 500 feet and was in a zone of hot air. The plane entered a steep nose dive and stalled; the crew lost control and the plane crashed, killing 163 people.
Asiana Airlines Flight 991: took off from Incheon International Airport for a night cargo flight to Shanghai Pudong International Airport on July 28, 2011. Almost half way to its destination, the crew declared a cargo fire emergency and wanted to divert to Jegu Airport. The fire got much worse, and the plane became totally uncontrollable. The plane flew into the Pacific Ocean, killing the two pilots instantly.
Air Midwest Flight 5481: took off from Charlotte/Douglas international airport to Greenville-Spartanburg international airport. The Beechcraft 1900D had its elevator range of motion cut to only 7 degrees downward but a full 14 degrees upward during a maintenance error and was overweight. The plane took off from runway 18R with 21 passengers and crew. Right after the gear was raised, the plane pitched up and the crew lost control. The plane stalled and pitched downward into a steep dive. It crashed into a corner of an aircraft hangar, killing all 21 people aboard instantly.