Landing

Landing refers to the placement of a space -, air - or watercraft on the ground or to a designated landing site. Usually the flight is completed after the descent and approach phases of flight with the landing maneuver. Does the landing or the landing may be canceled, nor follow the missed approach.

• 2.1 Hard Landing
• 2.2 Soft Landing

Landing of an aircraft

When landing is called the flight phases from the beginning of the approach to a stop or slow rolls. During this flight phase, which lasts about 2 to 10 minutes depending on the altitude, the total energy must (kinetic potential energy), which owns the aircraft to beginning of the approach, are specifically degraded. For this purpose, the amount of energy (speed) must already be in the air by increasing the resistance ( Buckle, flaps, etc.) are removed, as it allows the safe operation of the aircraft. Thus - and due to land against the wind - the landing speed is reduced, which is between about 50 km / h ( gliding ) and 300 km / h ( scheduled flights ). The remaining energy must be removed on the ground.

The landing of an airplane consists of the phases of the approach, flare, flare, touchdown and rollout.

During the landing approach speed is reduced to the safe approach speed. This must have a sufficient reserve to stall speed. As an optimal approach speed applies to powered aircraft, the stall speed factor of 1.3 times. This speed is called the reference speed (VREF ). These will be added depending on the aircraft type, the half or a third of the wind speed and wind gusts possible. The rate must not be higher than the maximum speed for extended flaps ( VFE - Flaps Extended) and out landing gear ( VLE - Landing Gear Extended). This speed is called the target speed ( VTRG - Target speed or VAPP - Approach Speed). In commercial aviation, these speeds are in front of each landing approach laid down in the so-called Approach Briefing, because the stall speed is dependent on weight and must be determined to date always. In light aircraft the reference speed is added, if a safety margin, for example, in the case of strong winds. For sailplanes, the landing speed is the best glide speed (VY ) plus 10 % ( against the wind or turbulence plus 20%). Since no through gliders starting is possible that increased speed is used as a safety margin.

While light aircraft usually end up with the engine at idle, this is not applied in larger machines. The cause lies in the good for landing glide to the machines and the associated difficulty of reducing speed. The danger of floating would be too great. For this reason one resorts to a trick: In the higher stages of the high -lift devices ( flaps ) generate this not only increased buoyancy, but also intentionally a high air resistance. The glide of typically 3 ° can then be met only by the administration of additional thrust. The speed can now be very effectively influenced by the combination of shear and trim and kept constant. A further advantage of the jet is the fact that in case of a go-around maneuver, the acceleration time of the engine is significantly reduced. With most machines, the landing thrust is about 45-65 % N1. When feeding Abfangbogens the thrust is reduced usually on idle.

Under the interception (Round Out, Break) is defined as the transition ( flaring ) from the approach ( descent ) in a parallel flight along the ground.

In the subsequent flare airspeed is gradually reduced in light aircraft, and the aircraft is achieved at minimum ride on. Decreasing flight speed of the lift is increased by increasing the angle of attack. Since this also increases the resistance to the wings, the angle of attack must be increased more rapidly with decreasing ride.

An airliner is flown with the approach speed VAPP. After passing the runway threshold at 50 feet height ( B ) is reduced the rate of descent in a dependent on the aircraft type Abfanghöhe with a slight increase in angle of attack and the aircraft is out of the flare with the resulting from the break pitch ( slope of the airplane's longitudinal axis ) on.

To mount on the water, there is inconsistent recommendations.

The larger the stall speed of the aircraft, the higher the corresponding seating velocity and thus, the remaining energy, which has to be removed at the bottom.

Depending on this, the required landing distance ( distance from the touchdown point to a standstill ). To shorten this, in large aircraft generously sized and cooled disc brakes are used. The aerodynamic resistance of the extended flaps will still stay effective. In order to prevent the aircraft due to the high coefficient of lift ( by the flap deflection ) again stands out shortly (jump landing), are activated immediately when putting the so-called spoiler to destroy the buoyancy and increase the resistance even further. For commercial aircraft, the spoilers are controlled by a complex logic to check different conditions, depending on aircraft type. There is also the possibility of the thrust reverser to increase the braking effect in many propeller and jet engines. Rarely brake shields are used instead.

When landing a military aircraft on an aircraft carrier there is no intercept and no flare. The approach ends at touchdown and goes directly into the ground run. A rope that can be hooked into the catch of the hook of the carrier aircraft, the aircraft withdraws its kinetic energy. However, you have to give when putting full thrust to durchzustarten should you have missed the rope. This aircraft and pilot at the abrupt braking maneuvers learn an enormous deceleration.

A landing can be (except in gliders ) aborted in nearly every phase. This is referred to by starting ( go-around ). Even after putting during coasting can still be started as long as activated yet no reverse thrust ( if available). As a maneuver is called then the Touch and Go ( Touch and Go). When landing on an aircraft carrier, the engine is brought up to full power in order to shorten the time in case you need a go-around until the engine responds and delivers the full power just before touchdown. Accesses the catch hook a rope that the aircraft is decelerated, and the pilot throttles the engines immediately. A landing attempt, in which the safety rope is missed and a go-around is necessary Bolter ( rivet ) is called.

At high approach speeds, the landing distance ( distance from the beginning of interception to touchdown ) can be significantly larger than the landing distance. This depends not only on the speed, but also the weight and the wind. Pilots, who have to make do with very small land areas ( bush pilot ), apply special short landing techniques. Usually, this means reducing the reference speed to just above the minimum speed. A carelessness on the landing approach means strong sagging and in the worst case, tipping over one of the two wings. Brief landings require high concentration and not to unsteady wind.

Commercial aircraft to land after a standard landing technique, which always is aiming for a point 1,000 feet beyond the runway threshold.

For take-offs and landings of all air sports equipment and aircraft is in Germany airport duty free, with the exception of balloons. For sailplanes an outside landing permission is normally granted.

Alternate landing

An alternate landing is the normal landing of an aircraft that is not carried out at the destination aerodrome, but at the alternate aerodrome. Reasons for this may be a short-term blocking of the destination aerodrome or deteriorating weather. In the event of a possible alternate landing a fuel reserve must for all flights, whether private or commercial, are carried which is the normal route from the destination airport to the alternate aerodrome 30 minutes. The alternate landing is rarely an emergency landing, which presupposes an air emergency during flight.

Field landing

From an outside landing one speaks generally, whenever the ground contact of a landing aircraft or parachutist not on an approved runway (or the landing site ) or is performed outside of the available landing distance of an operating airfield, but for example in the outdoor area, on a road or on a closed airfield.

When skydiving adverse wind conditions are usually responsible for ensuring that the target field can not be achieved; there other hand, there also planned external charges, but these must be booked in advance.

When gliding field landings are not unusual since gliders can be used as the driving power only their height, they usually reach about updrafts. Find a glider at low altitude off an airfield no more headwind, it must end up outside and is later picked up by a vehicle. This is often referred to in the report as inaccurate emergency landing.

Precautionary landing

A precautionary landing is when the pilot decides for a landing in order to avoid an imminent crisis, but which is not yet in place at the time of this decision. So the pilot has enough time to fly to an adequate aerodrome or to find a suitable site for a field landing.

Reasons for a precautionary landing can be:

• Unexpected weather phenomena which call for further flying or reversing impossible
• Instrument failure
• Unusual behavior of the engine (but no engine failure yet)
• During the flight, it is found that the fuel is no longer enough to the planned airfield
• During a visual flight without night rating is determined that the next airfield can not be reached before nightfall
• Failure of one engine in a multi-engine machines
• Case of illness without danger to life
• Malaise of a pilot
• At the bottom there are people that are in great danger and need help

A precautionary landing must not be hindered. An approval of the aeronautical authorities for a restart is explicitly not required. The owner of the land on which was landed, the restart should not hinder. However, the pilot has over the property owner an obligation to provide information ( information on the holder and insurance certificate acc. § 25 LuftVG ).

Emergency landing

To make an emergency landing is when a landing was forced by an emergency. Reasons for this may be:

• Fire on board
• Severe or not to classify defects or damage to the aircraft, which are detected during the flight
• Acute fuel shortage
• Storms and turbulence
• Serious engine problems
• Failure of all engines
• Acute life-threatening illness or injury of a passenger or crew member
• Malaise of both pilots

The emergency landing made ​​in the best case on an airfield, often in an open area ( field landing ) or as ditching on water surfaces. It is sometimes accompanied by comprehensive measures of the emergency services on the ground. After an emergency landing is a restart permitted only after authorization by the competent national aviation authority (as opposed to precautionary landing ), § 25, Section 2, No. 2, sentence 2 LuftVG.

A special kind of emergency landing, the " medical emergency landing " dar. deteriorates during transport of a patient with a rescue helicopter, his condition significantly, the helicopter must land between possibly to allow a better treatment. The restart is necessary in that case no approval.

Target landing

A target landing is a landing without engine power (ie, gliding ) from a specified level (usually 2000 ft above ground level) to a fixed landing field. It is a good exercise for Foreign Affairs and emergency landings, is required in the exam for pilots and afterwards gladly performed by pilots for training purposes. In particular, the assessment and classification of the available height is practiced for a gliding flight: The flight path must be chosen so after feeling that it ends exactly at the specified touchdown point.

In the test for pilots landing the target is within a specified range 150m of the runway must be done.

Belly landing

A belly landing is a landing with landing gear retracted, which can lead to severe damage of the aircraft underside. It can be performed with a damaged or faulty landing gear landing gear control.

Experience shows that it comes with gliders repeatedly landing without landing gear because the pilot forgot to extend the landing gear. Usually it comes only too low damage when landed on a grass runway, on a runway, however, the damage is immense. Therefore, many gliders have a warning device ( " landing gear warning "), which warns the pilot by an audible signal when the brakes (which are almost exclusively used for landing ) are activated, but the landing gear is retracted yet. If the brake flaps used only late during the landing approach, but there is a risk that the pilot himself, while trying, at low altitude nor extend the landing gear is not sufficiently focused on the landing, causing damage that is much larger than that would have been caused by a belly landing. Therefore, some pilots or associations consciously avoid a landing gear warning.

Stopover

An intermediate landing is a temporary stay between a source and a destination. It is used either to transfer air passengers, for transshipment of cargo or for refueling of fuel. Some airlines suspend their flights regularly to cost to refuel kerosene.

Long landing

For traffic reasons sometimes wish the pilot or air traffic control for a long landing (English long landing ). That is the fitting far behind the officially designated touchdown point. This requires a sufficiently long runway. Of course, the reduced response to incidents security because the tolerance is increased. In the commercial aviation will always landed in the defined landing zone. If necessary, it can be stretched by rolling out fuel efficient use of brakes.

The traffic-related reasons for a long landing can be:

• Rapid reaching the turnoff for the roll-off
• Shortening of the taxi route to the terminal, thus saving time and fuel savings
• Faster clearing the central portion of the runway, which is to be crossed by other aircraft
• Flight over wake vortex, which has generated a previously landed plane

Crosswind landing

If crosswind landings, the pilot must maintain the alignment of the runway and continued on the runway baseline against the lateral drift by the wind. Crosswind landings generally provide higher demands on the skill of the pilots and landings without significant crosswind.

Three-point landing

The three-point landing is a landing technique for Spornradflugzeuge. In this case, the aim is the same set up with all three wheels on the ground. The advantage of this landing technique is that ( aircraft nose is pointing up ) because of the high angle of attack is placed at the lowest possible speed and roll distance is therefore very short.

The more common today Bugradflugzeuge contact the main landing gear on first. In Spornradflugzeugen then one speaks of a wheel landing, which offers advantages in strong crosswinds.

Landing a spacecraft

Hard Landing

As a hard landing is called the unbridled impact of a missile ( lunar or planetary probe ) on the solid surface of a celestial body. In general, the missile is destroyed in the process and can provide only during the descent phase data. Penetrators, which survive even a hard landing followed by penetration into heaven body function, are under development and initial tests were unsuccessful.

In the first lunar probes the USA and the USSR several times a hard landing on Earth's satellite was planned, but instead it just came to a flyby. The accuracy at the start ( final speed and direction of the uppermost stage rocket ) was not sufficient and was not enough for the meeting of the moon on the necessary curved path.

• Propaganda success ( especially on the part of the Soviet Union during the Cold War )
• Advancement of technology and the orbital maneuvers
• First exploration of celestial bodies (eg close-ups of Ranger 7 to 9)
• Study of their atmospheres and magnetic fields
• Impactors and preparation of subsequent gentle landings
• From the 1990s incomplete braking or atmospheric braking
• Discontinuation of a penetrator on a minor planet or comet.

Soft landing

In the soft landing, the probe or her special lander is braked before the impact and protected during the impact itself (eg by an inflatable envelope ). For braking are braking rockets or existing atmosphere used parachutes. The missile remains intact and can perform tasks on the surface of the celestial body. Therefore, the soft landing is the preferred option today. On Venus, the parachute was in countries because of the dense atmosphere often dropped already at high altitude and the lander hit only slowed down by air resistance with 30 km / h on the surface. Thus can also be very hard a soft landing for our circumstances.

When returning to the earth missiles are divided into a landing on the mainland and a splashdown.

Others

Landing craft and air cushion vehicles can land on the banks and shores. Vessels enter ports to land on piers, jetties and piers, passengers and cargo.