Parachute Dropping
Unless a discrete code has already been assigned, pilots of transponder equipped aircraft should select Code 0033, together with Mode C, five minutes before the drop commences until the parachutists are estimated to be on the ground.
Aerobatic Manoeuvres
The use of Special Purpose Code 7004 shall be for solo or formation aerobatics, whilst displaying, practising or training for a display or for aerobatics training or general aerobatic practice. Any civil or military pilot may use this code whilst conducting aerobatic manoeuvres.
Unless a discrete code has already been assigned, pilots of transponder equipped aircraft should select Code 7004, together with Mode C, five minutes before commencement of their aerobatic manoeuvres until they cease and resume normal operations.
Pilots are encouraged to contact ATCUs and advise them of the vertical, lateral and temporal limits within which they will be operating and using the SSR Code 7004.
Controllers are reminded that SSR Code 7004 must be considered as unvalidated and the associated Mode C unverified. Traffic information will be passed to aircraft receiving a service as follows: ‘Unknown aerobatic traffic, (number) o’clock (distance) miles opposite direction/crossing left/right indicating (altitude) unverified (if Mode C displayed)’.
Mode S Aircraft Identification
To ensure that you comply with ICAO airborne equipment requirements and for the latest details on Mode S please refer to ENR 1.6.
Transponder Failure
Failure before intended departure
If the transponder fails before intended departure and cannot be repaired pilots shall:
(a) plan to proceed as directly as possible to the nearest suitable aerodrome where repair can be made;
(b) inform ATS as soon as possible preferably before the submission of a flight plan. When granting clearance to such aircraft, ATC will take into account the existing and anticipated traffic situation and may have to modify the time of departure, flight level or route of the intended flight;
(c) insert in item 10 of the ICAO flight plan under SSR the letter N for complete unserviceability of the transponder or in the case of partial failure, the letter corresponding to the remaining transponder capability as specified in ICAO Doc 4444, Appendix 2.
Failure after departure
If the transponder fails after departure or en-route, ATS Units will endeavour to provide for continuation of the flight in accordance with the original flight plan. In certain traffic situations this may not be possible particularly when the failure is detected shortly after take-off. The aircraft may then be required to return to the departure aerodrome or to land at another aerodrome acceptable to the operator and to ATC. After landing, pilots shall make every effort to have the transponder restored to normal operation. If the transponder cannot be repaired then the above failure prior to departure provisions – (a) to (c) – should be applied.
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本文链接地址：Guide to Visual Flight Rules (VFR) in the UK(33)
