8. SSR GENERAL Flashcards
What are the methods of identification when using SSR data?
AS may be identified by one or more of the following methods:
a. Observation of the pilot’s compliance with the instruction to select a discrete four-digit code.
b. Recognising a validated four digit code previously assigned to an AS callsign. When code/callsign conversion procedures are in use an the code/callsign pairing can be confirmed, the callsign displayed in the data block may be used to establish and maintain identity.
c. Observing an IDENT feature when it has been requested. Caution must be exercised when employing this method because simultaneous requests for transmissions within the same area may result in misidentification. AS displaying the conspicuity code 7000 are not to be identified by this method.
What are the rules concerning validation of Mode 3A?
a. A controller assigning any Mode 3A code should validate that code by checking as soon as possible, either by direct reference to his surveillance display or with the assistance of another controlling agency, that the data displayed corresponds with the code which has been assigned.
b. If this is not the case, the pilot should be instructed to reset the assigned code. Where this fails to achieve display of the assigned code then he should be instructed to select 3A 0000.
c. If a corrupt code still exists, the pilot should normally be instructed to switch off the transponder. However, where approved by local procedure and providing that Mode C has been verified, the corrupt code may be retained to assist identification and tracking. Associated ATS units should be informed of the retention of the corrupt data.
d. At units where code callsign conversion equipment is in use, procedures to ensure the correct correlation of the callsign with the assigned code should be utilised by controllers and included in Local/Unit Orders.
e. Where a controller can ascertain from the Code Allocation Plan that a discrete Mode 3A code has been assigned by a unit capable of validating the code, and has not been notified that the code is corrupt, then that code should be deemed validated.
When and how should Mode C data be verified?
Controllers should verify Mode C data transmitted by an AS for accuracy on initial contact once the AS has been positively identified. Mode C data should be verified by one of the following methods:
a. By a visual check of the data readout immediately on receipt of a pilot’s report giving his present or passing level. Particular care must be exercised when assessing the accuracy of the Mode C readout if the AS is climbing or descending.
b. By co-ordination with another unit.
What are the criteria for assessing level occupancy when using verified Mode C data:
a. In Level Flight?
b. Vacating an Assigned Level?
c. Passing a Level?
d. Reaching a Level?
a. In Level Flight. An AS should be considered to be at an assigned level provided that the Mode C readout indicates 200ft or less from that level.
b. Vacating an Assigned Level. An AS that has been cleared to leave a level should be considered to have done so when the Mode C readout indicates a change of 400ft or more in the anticipated direction.
c. Passing a Level. An AS climbing or descending should be considered to have passed through a level when the Mode C readout indicates that the level has passed by 400ft or more in the required direction.
d. Reaching a Level. An AS should be considered to have reached an assigned level when 3 successive Mode C readouts indicate 200ft or less from that level.
What is the procedure if Mode C data is found to be outside permitted limits?
If on verification or during the subsequent provision of an ATS a discrepancy of more than 200ft is observed, the controller should ask the pilot to confirm his altimeter setting and level. If the discrepancy remains the pilot should be instructed to switch off Mode C. If independent switching of Mode C is not possible, the pilot should be instructed to select SSR Code 0000 to indicate a transponder malfunction.
What SSR code should be used by AS operating into and out of the UKLFS?
a. FW ASs. On entering, and throughout the duration of flight within the UKLFS, FW ASs are to transmit SSR Code 7001 with Mode C. On exiting the UKLFS, either:
(1) If a radar service is required, retain SSR Code 7001 with Mode C until alternative instructions are passed by an ATC Unit.
(2) If a radar service is not required, when possible after climbing through 2000ft MSD, change to SSR Code 7000 with Mode C.
b. RW AS. On entering, and throughout the duration of flight within the UKLFS, RW ASs are to transmit SSR Code 7000 with Mode C (if fitted). On exiting the UKLFS, should a radar service be required, change to SSR Code 7001 with Mode C (if fitted).
What factors should units consider when developing SSR alone procedures?
a. Surveillance Radar coverage of adjacent units in order handover AS being provided with an ATS.
b. The potential to deploy controllers to adjacent units.
c. Local airspace agreements.
d. Agreements with local aerodrome and airspace activity providers (e.g. parachuting or paragliding organisations).
e. Management of IFR procedures to mitigate the impact of hazardous areas (e.g. adjusting instrument procedures to avoid known gliding sites).
f. The scheduling of PSR maintenance programmes.
