ATS Surveillance Systems 4 Flashcards
According to MATS 1, how are Mode-C responses used to apply vertical separation? Include in your answer when Mode-C cannot be used to apply vertical separation, but do NOT include the occasions when the intentions of Mode-C transponding aircraft are unknown.
When SSR is used to assess vertical separation the Mode C responses are to be continually monitored to ensure that the vertical distance is never less than the prescribed minimum.
Vertical separation using Mode C is not applied against aircraft transponding A0000.
Minimum vertical separation may be applied between verified Mode C transponding aircraft provided the intentions of both aircraft are known to a controller because either:
1) They are under his control
2) They have been coordinated or,
3) They are operating in accordance with established agreements
As stated in MATS 1:
a) Describe when and how controllers are to verify the accuracy of Mode-C data
b) Detail when a Mode-C readout can be assumed to have been verified
c) What action must a controller take if he observes a discrepancy involving a Mode-C readout?
a) Controllers are to verify the accuracy of Mode C data, once the aircraft has been identified and the Mode A validated, by checking that the readout indicated 200 feet or less from the level reported by the pilot. If the aircraft is climbing or descending, the pilot is to be instructed to give a precise report as the aircraft passes through a level. Verification may be achieved with assistance of an ATSU with which the aircraft is in contact.
b) A Mode C readout can be assumed to have been verified if it is associated with a deemed validated Mode A code.
c) There is no requirement to monitor level readouts when Mode C information is not being used to provide vertical separation. However, if a controller observes a discrepancy the pilot is to be asked to confirm his altimeter setting and level. If the discrepancy remains, the pilot is to be instructed to switch-off Mode C. If independent switching of Mode C is not possible the pilot is to be instructed to select A0000.
According to MATS 1, how is level occupancy assessed using Mode-C? Include in your answer when an aircraft has reached, left, passed and is maintaining a level and how this information may be displayed?
The following criteria apply when assessing the vertical position of a Mode C transponding aircraft:
1) An aircraft may be considered to be at an assigned level provided that the Mode C readout indicates 200 feet or less from that level
2) An aircraft which is known to have been instructed to climb or descend may be considered to have left a level when the Mode C readout indicates a change of 400 feet or more from that level and is continuing in the anticipated direction.
3) An aircraft climbing or descending may be considered to have passed through a level when the Mode C readout indicates that the level has been passed by 400 feet or more and continuing in the required direction.
4) An aircraft may be considered to have reached an assigned level when three successive Mode C readouts indicate 200 feet or less from that level.
Mode C information is normally displayed as a Flight Level but on some ground equipment the vertical position of an aircraft flying below a pre-determined datum is displayed as an altitude.
As stated in MATS 1, what are the minimum terrain clearance requirements when assigning levels to IFR flights in receipt of a Radar Control Service? Exclude the phases of flight for within the defined approach area and within the Surveillance Minimum Altitude Area.
Within 30 miles of the radar antenna associated with the unit providing the service:
1,000 feet above any fixed obstacle within:
1) 5 miles of the aircraft and
2) 15 miles ahead and 20 degrees either side of the aircraft’s track
When the aircraft is within 15 miles of the antenna, and provided a SMAC or approved procedure has been notified, the 5 miles in (1) and the 15 miles in (2) may be reduced to 3 and 10 miles respectively.
Outside the phases above:
1,000 feet above any fixed obstacle:
1) Which lies within 15 miles of the centreline of any airway or
2) Within 30 miles of the aircraft (for all other flights)
In sections of airways where the base is defined as a flight level, the lowest usable level normally provides not less than 1,500 feet terrain clearance.
As a radar controller, what would be your actions in the event of a surveillance system failure, according to MATS 1? Do not detail the return to service of a previously failed surveillance system.
In the event of surveillance system failure, the controller shall inform aircraft under control of the failure and apply local contingency procedures, which shall be detailed in MATS Part 2. Reduced vertical separation of half the applicable vertical separation (e.g. 500 feet where a controller would normally apply 1,000 feet vertical separation and 1,000 feet where a controller would normally apply 2,000 feet vertical separation) may be employed temporarily if standard separation cannot be provided immediately. When reduced vertical separation is employed, pilots shall be informed and essential traffic information passed as necessary.
According to the AIP, detail the pilots’ responsibilities with regard to SSR operating procedures for codes other than special purpose codes, 7000, 0033 and 7004.
Pilots shall:
1) If proceeding from an area where a specific Mode-A code has been assigned to the aircraft by an ATS unit, maintain that code setting unless otherwise instructed.
2) Select or reselect Mode-A codes, or switch off equipment when airborne only when instructed by an ATS unit
3) Acknowledge Mode-A code setting instructions by reading back the code to be set.
4) Select Mode-C pressure altitude reporting mode of the transponder simultaneously with Mode-A unless otherwise instructed by an ATS unit
5) When reporting levels under routine procedures, or when requested by ATC, state the current altimeter reading to the nearest 100ft. This is to assist in the verification of Mode-C pressure altitude reporting data transmitted by the aircraft.
ISASW
According to the AIP, what are the pilots responsibilities and actions when an aircraft transponder fails before departure and cannot be repaired? Include ATC considerations in your answer, but not the temporary failure of Mode-C alone.
If the transponder fails before intended departure and cannot be repaired, pilots shall:
1) Plan to proceed, as directly as possible, to the nearest suitable aerodrome where a repair can be made.
2) Inform ATS as soon as possible, preferably before the submission of a flight plan. When granting clearances 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.
3) 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, including unserviceability of any Mode-S functionality.
According to the AIP, what are the actions and responsibilities of ATS units when an aircraft transponder fails after departure? Include in your answer the pilot’s responsibilities where appropriate, but not the temporary failure of Mode-C alone.
If the transponder fails after departure, or en-route, ATS Units will endeavour to provide for the continuation of the flight in accordance with its original flight plan. In certain traffic situations this may not be possible, particularly when the failure is detected shortly after the 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 provisions for failure before departure apply.
