A belly landing or gear-up landing occurs when an aircraft

Aircraft

An aircraft is a vehicle that is able to fly by gaining support from the air, or, in general, the atmosphere of a planet. An aircraft counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines.Although...

 lands without its landing gear

Landing Gear

Landing Gear is Devin the Dude's fifth studio album. It was released on October 7, 2008. It was his first studio album since signing with the label Razor & Tie. It features a high-profile guest appearance from Snoop Dogg. As of October 30, 2008, the album has sold 18,906 copies.-Track...

 fully extended and uses its underside, or belly, as its primary landing device. Normally the term gear-up landing refers to incidents in which the pilot forgets to extend the landing gear, while belly landing refers to incidents where a mechanical malfunction prevents the pilot from extending the landing gear.

During a belly landing, there is normally extensive damage to the airplane. Belly landings carry the risk that the aircraft may flip over, disintegrate, or catch fire if it lands too fast or too hard. Extreme precision is needed to ensure that the plane lands as straight and level as possible while maintaining enough airspeed to maintain control. Strong crosswinds, low visibility, damage to the airplane, or unresponsive instruments or controls greatly increase the danger of performing a belly landing. Still, belly landings are one of the most common types of aircraft accidents, and are normally not fatal if executed carefully.

Pilot error

The most common cause of gear-up landings is the pilot

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...

 simply forgetting

Pilot error

Pilot error is a term used to describe the cause of an accident involving an airworthy aircraft where the pilot is considered to be principally or partially responsible...

 to extend the landing gear before touchdown. On any retractable gear aircraft, lowering the landing gear is part of the pilot's landing checklist

Checklist

A checklist is a type of informational job aid used to reduce failure by compensating for potential limits of human memory and attention. It helps to ensure consistency and completeness in carrying out a task...

, which also includes items such as setting the flaps, propeller and mixture controls for landing. Pilots who ritually perform such checklists before landing are less likely to land gear-up. However, some pilots neglect these checklists and perform the tasks by memory, increasing the chances of forgetting to lower the landing gear. Even studious pilots are at risk, for they may be distracted and forget to perform the checklist or be interrupted in the middle of it by other duties such as collision avoidance or another emergency. The common nature of gear-up landings caused by pilot error has led to an adage

Adage

An adage is a short but memorable saying which holds some important fact of experience that is considered true by many people, or that has gained some credibility through its long use....

 within the aviation community: "There are two types of pilots: Those that have landed gear up, and those that will."

All aircraft with retractable landing gear are required to have a way to indicate the status of the landing gear, which is normally a set of lights that change colors from red to amber to green depending on whether the gear are up, in transit, or down. However, a distracted pilot may forget to look at these lights. This has led to aircraft designers building extra safety systems in the aircraft to reduce the possibility of human error. In small aircraft this most commonly takes the form of a warning light and horn which operate when any of the landing gear is not locked down and any of the engine throttle

Throttle

A throttle is the mechanism by which the flow of a fluid is managed by constriction or obstruction. An engine's power can be increased or decreased by the restriction of inlet gases , but usually decreased. The term throttle has come to refer, informally and incorrectly, to any mechanism by which...

s are retarded below a cruise power setting. However, the horn has been useless in situations when the pilot was unfamiliar with the aircraft and did not know what the horn sounding was meant to indicate. Pilots have sometimes confused the landing gear warning horn with the stall warning horn. In other cases, pilots cannot hear the horn on older aircraft due to wearing a modern noise-canceling

Active noise control

Active noise control is a method for reducing unwanted sound.- Explanation :...

 headset

Headphones

Headphones are a pair of small loudspeakers, or less commonly a single speaker, held close to a user's ears and connected to a signal source such as an audio amplifier, radio, CD player or portable Media Player. They are also known as stereophones, headsets or, colloquially, cans. The in-ear...

.

In larger aircraft the warning system usually excludes the engine power setting and instead warns the pilot when the flaps are set for landing but the landing gear is not. An alternative system uses the ground proximity warning system

Ground Proximity Warning System

A ground proximity warning system is a system designed to alert pilots if their aircraft is in immediate danger of flying into the ground or an obstacle. The United States Federal Aviation Administration defines GPWS as a type of terrain awareness warning system...

 or radar altimeter

Radar altimeter

A radar altimeter, radio altimeter, low range radio altimeter or simply RA measures altitude above the terrain presently beneath an aircraft or spacecraft...

 to engage a warning when the airplane is close to the ground and descending with the gear not down. Most airliner

Airliner

An airliner is a large fixed-wing aircraft for transporting passengers and cargo. Such aircraft are operated by airlines. Although the definition of an airliner can vary from country to country, an airliner is typically defined as an aircraft intended for carrying multiple passengers in commercial...

s incorporate a voice message system

Bitching betty

Bitching Betty is the slang term some pilots and crew use when referring to the voice warnings used by some aircraft systems....

 which eliminates the ambiguity of a horn or buzzer and instead and gives the pilot a clear verbal indication: "GEAR NOT DOWN". In addition, large aircraft are designed to be operated by two pilots working as a team

Crew Resource Management

Crew resource management or Cockpit resource management is a procedure and training system in systems where human error can have devastating effects. Used primarily for improving air safety, CRM focuses on interpersonal communication, leadership, and decision making in the cockpit...

. One flies the aircraft and handles communications and collision avoidance, while the other operates the aircraft systems. This provides a sort of human redundancy which reduces the workload placed on any one crew member, and provides for one crew member to be able to check the work of the other. The combination of advanced warning systems and effective crew training has made gear-up landing accidents in large aircraft extremely rare.

In some cases the pilot may be warned of an unsafe gear condition by the aircraft's flying characteristics. Often very sleek, high-performance airplanes will be very difficult to slow to a safe landing speed without the aerodynamic drag of the extended landing gear.

Mechanical failure

Mechanical failure is another cause of belly landings. Most landing gear are operated by electric motor

Electric motor

An electric motor converts electrical energy into mechanical energy.Most electric motors operate through the interaction of magnetic fields and current-carrying conductors to generate force...

s or hydraulic actuator

Hydraulic cylinder

A Hydraulic cylinder is a mechanical actuator that is used to give a unidirectional force through a unidirectional stroke. It has many applications, notably in engineering vehicles.- Operation :...

s. Multiple redundancies are usually provided to prevent a single failure from failing the entire landing gear extension process. Whether electrically or hydraulically operated, the landing gear can usually be powered from multiple sources. In case the power system fails, an emergency extension system is always available. This may take the form of a manually-operated crank or pump, or a mechanical free-fall mechanism which disengages the uplocks and allows the landing gear to fall due to gravity.

In cases where only one landing gear leg fails to extend, the pilot may choose to retract all the gear and perform a belly landing because he may believe it to be easier to control the aircraft during rollout with no gear at all than with one gear missing.

Some aircraft, like the A-10 Thunderbolt II

A-10 Thunderbolt II

The Fairchild Republic A-10 Thunderbolt II is an American single-seat, twin-engine, straight-wing jet aircraft developed by Fairchild-Republic in the early 1970s. The A-10 was designed for a United States Air Force requirement to provide close air support for ground forces by attacking tanks,...

, are specifically designed to make belly landings safer. In the A-10's case, the retracted main wheels protrude out of their nacelles, so the plane virtually rolls on belly landings.

Examples

On 4 July 2000 Malév Flight 262

MALÉV Flight 262

Malév Flight 262 was a flight from Budapest Ferihegy International Airport to Thessaloniki International Airport. On 4 July 2000, a Tupolev Tu-154 used on this flight performed a gear-up touchdown during the landing at Thessaloniki, skidded on the runway, but was able to take off and land normally...

, a Tupolev Tu-154

Tupolev Tu-154

The Tupolev Tu-154 is a three-engine medium-range narrow-body airliner designed in the mid 1960s and manufactured by Tupolev. As the mainstay 'workhorse' of Soviet and Russian airlines for several decades, it serviced over a sixth of the world's landmass and carried half of all passengers flown...

, performed a gear-up touchdown during the landing and skidded on the runway, but was able to take off and land normally after a go-around

Go-around

A go-around is an aborted landing of an aircraft that is on final approach.- Origin of the term :The term arises from the traditional use of traffic patterns at airfields. A landing aircraft will first join the circuit pattern and prepare for landing in an orderly fashion...

. No injuries were reported.

In July 2006 an Australian

Royal Australian Air Force

The Royal Australian Air Force is the air force branch of the Australian Defence Force. The RAAF was formed in March 1921. It continues the traditions of the Australian Flying Corps , which was formed on 22 October 1912. The RAAF has taken part in many of the 20th century's major conflicts...

 F-111 bomber made an emergency landing after a wheel on the landing gear

Undercarriage

The undercarriage or landing gear in aviation, is the structure that supports an aircraft on the ground and allows it to taxi, takeoff and land...

 fell off after take-off

Takeoff

Takeoff is the phase of flight in which an aerospace vehicle goes from the ground to flying in the air.For horizontal takeoff aircraft this usually involves starting with a transition from moving along the ground on a runway. For balloons, helicopters and some specialized fixed-wing aircraft , no...

. The pilot circled the airfield for three hours burning off fuel before coming in with his landing gear retracted and arrestor hook deployed. The F-111 suffered only superficial damage.

On 1 November 2011 LOT Polish Airlines Flight 016, a Boeing 767

Boeing 767

The Boeing 767 is a mid-size, wide-body twin-engine jet airliner built by Boeing Commercial Airplanes. It was the manufacturer's first wide-body twinjet and its first airliner with a two-crew glass cockpit. The aircraft features two turbofan engines, a supercritical wing, and a conventional tail...

, declared an emergency with a loss of landing gear en route from Newark Liberty International Airport

Newark Liberty International Airport

Newark Liberty International Airport , first named Newark Metropolitan Airport and later Newark International Airport, is an international airport within the city limits of both Newark and Elizabeth, New Jersey, United States...

 to Warsaw Chopin Airport. The aircraft involved was the newest 767 airframe in the fleet. It made a belly landing (see video) in Warsaw with a small fire, but all passengers and crew were evacuated with no injuries. The airport was closed for over a day afterwards.