Traffic pattern
The traffic pattern is a standardized approach and departure procedure for flights under visual flight rules (VFR). It serves z. B. the initiation of a safe landing approach, but also the protection of noise-sensitive areas around the airfield . There are VFR approach charts for every airport, on which the flight path and the flight altitude are shown in the traffic pattern. Otherwise, the standard ICAO traffic pattern applies (sketch opposite). The pilot may only deviate from the traffic pattern if the aircraft is required to operate safely (e.g. in emergencies) or if the responsible ground radio station allows him to do so, otherwise he will commit an administrative offense according to the LuftVG . Hang-gliders and paragliders fly a Landevolte instead of the traffic pattern .
Traffic laps are only determined and published for uncontrolled airfields. In controlled courts conduct air traffic controllers of the air traffic control aerodrome traffic.
Unless otherwise stipulated by the responsible aviation authority, traffic patterns are flown at a distance of approx. 1.5 km from the runway and to the left (counterclockwise) so that the pilot sitting on the left can keep an eye on the runway during the entire maneuver . Traffic laps are normally left after take-off via the cross take-off or the counter-approach and approached for landing via the counter-approach.
In the case of location reports in the traffic area via aircraft , the information about the radio call sign and location must be given.
The traffic pattern consists of five parts.
Departures ( English departure )
The aircraft takes off in take-off configuration. In aircraft with retractable landing gear, the landing gear is retracted once a safe rate of climb has been reached. The landing flaps are retracted about 150 m above the ground and the landing lights are switched off again. After about 1.5 km, turn into cross departure.
Gliders that take off on the winch are brought into normal flight position (level flight) after the winch cable has been released.
Transverse departure ( English crosswind )
This is so called because the further departure takes place 90 ° across the runway. In powered flight, you climb to the traffic lane height specified in the approach map. It is typically reached approximately 250 m (800 feet) above the airfield level. The transverse take-off is followed for about 1.5 km. Then you turn into the opposite approach.
Counter approach ( English downwind )
The counter approach (wind at best in the rear) serves as the transition from descent or cruising flight to preparing the aircraft for landing. For this purpose, the carburetor preheating is switched on (if not already done in the previous descent) in powered aircraft . You do not need to do this in diesel aircraft or aircraft with injection engines. On the counter-approach, the speed is reduced to such an extent that the flaps can safely be extended in stages. There is a corresponding marking on the airspeed indicator (white arc).
This increase in lift is also associated with an increase in the induced drag. The pilot can compensate for this with increased engine power or simply use it as a braking effect.
With gliding, however, it is different. Glider pilots even increase the airspeed before the landing approach and check whether the flaps are retracted during the take-off check. Since the spoilers on gliders (often incorrectly referred to as airbrakes in colloquial terms) are only used to lower the aircraft. The sink rate is controlled with the spoilers.
At least five minutes before entering the traffic pattern, an approaching aircraft registers at the airfield via radio and normally flies into the opposite approach of the traffic pattern. The radio message informs both the flight controller of the landing site and other pilots who are approaching the site of his position and his intentions. In general, the counter approach is flown parallel to the runway alignment until the runway threshold is about 1.5 km behind the pilot (or about 45 ° behind the aircraft). However, this type of procedure is only recommended for comparatively slow aircraft. Pilots with faster aircraft start the stopwatch abeam the touchdown point and fly for another 30 seconds on a counter-approach. This guarantees a sufficiently long final approach that matches the speed of the aircraft. From the opposite approach, a curve is made into the transverse approach.
The position ( low key ) is located across from the touchdown point on the opposite approach . In gliding, when leaving the position, all landing preparations should be completed. In addition, the landing registration is canceled at this time.
In glider training, various flight maneuvers are practiced starting from the opposite approach. Before landing, the opposite approach is flown in again and the landing is initiated.
Transverse approach ( English base )
In the transverse approach it is important to reduce speed and altitude by taking the throttle back on motorized aircraft, extending the landing gear again at this point at the latest and extending the flaps if necessary. Here it is usually 800 ft above ground on the counter approach to 500 ft above ground. The base leg ends with the last turn (Engl. Final Turn , also called "fourth curve"). When gliding, depending on the current altitude, the transverse approach is used to ensure a safe final approach.
Final approach ( English final )
After the last curve , you begin a continuous descent from 500 ft above ground to the touchdown point, the final approach. The aircraft should stabilize (with the landing lights switched on if necessary ) and at the correct approach and descent speed on the approach baseline ( centerline ), i.e. H. are in the extension of the runway. Approach and descent speeds are usually coordinated with one another in such a way that the descent (e.g. 500 ft per minute at 100 knots) is carried out in powered aircraft at an angle of 3 ° to the horizontal. Some airfields have approach aids such as PAPI , which visually indicate to the pilot that the approach angle is being adhered to. The landing is carried out after the final approach. Here the (landing) flaps are used to let the aircraft fly as slowly as possible: By extending the flaps, the lift is increased. In some aircraft, this also involves extending the slats , which also changes the surface profile. You touch down with the lowest possible but safe speed. This can vary depending on the weather.
When gliding, the last curve should end at a height of at least 100 m above the current height of the field. The final approach is started with a safety reserve (altitude and speed). With the help of the spoilers , which are not a buoyancy aid on a glider (and possibly flight maneuvers such as the slip ), a safe landing at the intended touchdown point is always possible, because this can specifically influence the rate of descent. Depending on the aircraft, the spoilers have little or no influence on the flown speed.
During pilot training, several traffic loops are often flown one after the other as training for take-off and landing. Instead of a final landing ( full-stop-landing ), a restart takes place after touch-down ( English touch-and-go ). Depending on the type of aircraft, the flaps initially either remain extended and are later retracted gradually with increasing airspeed or while taxiing on the ground (see also stall ).
Another approach variant is the low approach , in which a simulated landing approach is flown without touching the runway (for landing). The last landing after a series of circular flights is the full-stop landing.
Individual evidence
- ↑ Aviation regulations, LuftVo § 22
- ↑ a b NfL II 37 2000. (pdf) Regulation of air traffic. In: News for Aviators . German air traffic control , April 20, 2000, accessed on August 7, 2016 .
- ↑ Deutsche Flugsicherung (Ed.): Aviation Handbook . August 4, 2016, ENR 1-56.