Airfield traffic pattern

The traffic pattern is a standardized approach and departure procedures for flights under visual flight rules ( VFR). It is used, for example, the introduction of a safe landing approach, but also to protect noise-sensitive areas around the airfield. As a special feature in Germany and Austria, there are special approach plates on which the flight path and flight level is specified in the traffic pattern. Abroad, usually the standard traffic pattern is considered by ICAO ( adjacent sketch ). The pilot may deviate from the traffic pattern when the safe operation of the aircraft required (eg, conflicting traffic, clouds, performance of the aircraft, etc.).

Place rounds only be published at uncontrolled aerodromes. In controlled places this would limit the freedom of action of the tower controller too much.

Unless specified differently from the competent aviation authority, place rounds at a distance of approximately 1 NM (nautical miles ) from the runway and left ( counterclockwise) flown so that the left seated pilot to keep the runway during the entire maneuver in the eye can. Place rounds are usually abandoned after the start via the crosswind leg or downwind and fly to land on the downwind leg.

Regulations for the circling traffic is found in the NfL II 37 /2000.

The traffic pattern consists of five parts.

Hang gliders and paragliders fly instead of the space round a landing Volte.

Departure ( engl. departure )

The plane takes off in launch configuration. For airplanes with retractable landing gear is retracted from reaching a safe climb speed. In about 500 feet ( 150 m ) above the ground takes place the retraction of the flaps. You may be here also (on some airfields prescribed at startup) landing lights off again. After about 1 NM turning into the crosswind leg.

Gliders, which start on the winch are brought after the release of the winch cable in the normal flight position ( horizontal flight ).

Crosswind leg (English crosswind )

This is so called because the further departure 90 ° takes place across the web. During powered flight, climb to the specified in the approach chart circuit altitude. It is usually in the 1,000 feet (ft, 300 m ) reached by the current aerodrome elevation. The cross- departure followed about 1 NM. Then turn to the downwind leg.

Downwind (English downwind )

The downwind (wind, at best, in the back ) is to return from sinking or cruise to the landing preparation of the aircraft. Purpose (unless already done in the previous descent ) is turned on the carburetor heat when the engine airplanes. In diesel aircraft or aircraft with fuel injection engines you do not need to do that. In the downwind leg, the speed is reduced, so that the flaps can be extended gradually danger. There are on the airspeed indicator a corresponding mark (white sheet ).

This increase in lift is also associated with an increase in induced drag. The pilot can compensate for this by increasing engine power or simply use as a braking effect.

When gliding, however, is different. Glider pilots even increase the airspeed before landing and check the landing check, for example, if the flaps are retracted.

Before you join the traffic round an approaching aircraft on the airfield radio logs in and usually flies into the downwind leg of the traffic pattern. Through the radio message, both the Flight Director of the landing site as well as other pilots who fly to space, provides information about its position and intentions. In general, the downwind leg is flown parallel to the runway alignment until the runway threshold at the back of the pilot is about 1 NM (or about 45 ° behind the aircraft ). This Vorgehensart is only recommended for relatively slow aircraft. Pilots with faster aircraft start abeam the touchdown point the stopwatch and fly downwind for another 30 seconds. This guarantees a sufficiently long final approach that matches the speed of the aircraft. From the downwind leg is eingekurvt base leg.

Abeam the touchdown point in the downwind leg, the position ( engl. low key ). The glider should be completed when leaving the position all the land preparation. In addition, the land registration is issued at this time.

In the gliding training starting various flight maneuvers are practiced in training from the downwind leg. Before landing is again flown into the downwind leg and initiated the landing.

Base leg (English base)

In the base leg idea is to reduce speed and altitude by the gas to take back with the engine airplanes, the landing gear would eject when aircraft with retractable landing gear at the latest at this point again and the flap extends further as needed. Here ft is usually of 1000 decreased above ground above ground ft on the downwind leg at 500. The base leg ends with the last curve (English Final Turn, also called " fourth curve "). When gliding is used depending on the current altitude of the base leg to ensure a safe final approach.

Final Approach (English final)

After the last curve to start a continuous descent from 500 ft above ground level for the touchdown, the final approach. In this case, the aircraft should ( with possibly turned on landing lights ) and are stabilized with the right approach and descent on the extended center line (English Centerline ), that is, in the extension of the runway. Approach and descent are usually coordinated so that the descent (eg 500 ft per minute at 100 knots) at engine aircraft at an angle is carried out from 3 ° to the horizontal. After the final approach, the landing is performed. Here the (landing ) flaps serve to let fly the plane as slow as possible: By gradually extending the flaps, the wing area is increased, whereby the buoyancy is increased. For large aircraft so that a retraction of the slats is simultaneously connected, which additionally modifies the surface profile. You bet on with the least possible, but safe speed. This can vary due to weather conditions.

When gliding the last curve to be completed at a height of at least 100 m above the current field elevation. The final approach is begun with a safety reserve (height and speed). With the help of spoilers that are not buoyancy aids by a glider, (and possibly maneuvers, such as the Slip) is a safe landing at the intended touchdown always possible, because it targeted speed and descent rate can be influenced.

In practice, most traffic patterns in the training of powered flight pilots are flown for practicing takeoff and landing one after the other.

Instead of a final landing (English full -stop landing ) you can also put on and take off ( a Touch -and-go flying), in which one final glide at full throttle just after touchdown and starts again, the flaps remain initially extended and later be gradually retracted with increasing airspeed ( a premature retraction of the flaps at the even lower airspeed a slump would result because of the buoyancy for this speed would be too small, see also stall ). Depending on the recommendation of the manufacturer of the airplane type a retraction of the flaps is provided to the starting position while taxiing on the ground, because they would not rise enough with flaps fully extended due to air resistance. Another variation of this would be the deep overflight (low approach), in which a simulated landing approach is flown without touching the runway ( landing ). The last landing after a series of circling flights is the final landing (full -stop landing ).

Planes that are traveling under visual flight rules to fly, either at predetermined points in the approach charts or ( in cases where such marks are not specified ) in the downwind leg in the traffic circuit on or off. The actual landing is as described above.

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