(1) ATM - SSR Identification

Question 1

What is Radar contact? (1)

Answer 1

The situation which exists when the radar position symbol of a particular aircraft is seen and identified on a situation display

Question 2

What is Identification? (1)

Answer 2

The act of correlating a particular position indication with a specific aircraft target by means of laid down procedures

Question 3

What is Validation? (2)

Answer 3

• The task of checking that the correct code has been selected by the pilot and is shown on the situation display
• It is possible to achieve identification and validation simultaneously

IF YOU ALLOCATE A SQUAWK YOU MUST VALIDATE AND VERIFY IT!

Question 4

What is Correlation? (1)

Answer 4

• By means of a radar processor, SSR data may be correlated with stored flight plan data, enabling a code / callsign conversion to take place
• Unless correct validation procedures are carried out, the resulting correlation could give rise to incorrect data being displayed

Question 5

What is Verification? (1)

Answer 5

A check to confirm that the aircrafts Mode C read out is accurate within agreed parameters

Question 6

What is Mode A? (3)

Answer 6

• Squawk allocated to identify and aircraft
• ATCO shall inform pilot of identification (if outside CAS)
• It is no longer required to pass a position to the pilot unless the ATCO considers it necessary

Question 7

How may an Aircraft be identified using SSR and/or MLAT? (5)

Answer 7

• Recognition of the aircraft identification in an SSR and/or MLAT label; (nb #1)
• Direct recognition of the aircraft identification of a Mode S-equipped aircraft in an SSR and/or MLAT label
• By transfer of identification
• Observation of compliance with an instruction to set a specific code
• Observation of compliance with an instruction to squawk IDENT

Question 8

Can an Aircraft be identified when using an Conspicuity code? (1)

Answer 8

No

So no possible simultaneous identifications of multiple aircraft

Question 9

If the SSR code does not correlate with the assigned code, what would instruct the Pilot to do? (1)

Answer 9

Reset the code

Question 10

What shall the Pilot be instructed to do when an SSR code error exists and persists (2)

Answer 10

• To squawk A0000
• Tell the Pilot to turn the Transponder off

Question 11

How may a Mode A code be deemed validated? (1)

Answer 11

When the code set can be recognised by the Code Assignment Plan to have been assigned by an ATC unit capable of validating the code, providing the code has not been notified as being corrupt

Question 12

How can Mode C be assumed verified? (2)

Answer 12

• If associated with a deemed validated Mode A code
• May be achieved with assistance of another ATSU

Question 13

What will an ATCO do if an aircrafts Mode C shows an error and persists?

Answer 13

• Request the pilot to “check altimeter setting and confirm level”
• “Stop Squawk Altitude” or “Stop squawk Altitude, wrong indication” or “Squawk 0000” – to indicate a data error
  (if independent switching of Mode C is not possible)

Question 14

When is an aircraft maintaining an assigned level? (2)

Answer 14

Mode C readout indicates:
- ± 200ft - In RVSM (FL290 - 410)
- ± 300ft - Other airspace (But not less than ± 200ft)

Question 15

When has an aircraft vacated a level? (2)

Answer 15

• When instructed to climb or descend
• Mode C readout shows a change of more than 300ft from its previously occupied level and is continuing in the anticipated direction

Question 16

What is passing a level in climb / descent? (1)

Answer 16

An aircraft in climb or descent is considered to have crossed a level when the Mode C information indicates that it has passed this level in the required direction by more than 300 ft

Question 17

What is Reached an assigned level? (3)

Answer 17

Considered reached when (whichever is the greater):

• The elapsed time of 3 display updates
• 3 sensor updates
• 15 seconds

Since the Mode C information has indicated that it is within the appropriate tolerances of the assigned level

Question 18

How is transfer of identification effected? (8)

Answer 18

1. Designation by automated means, provided that only one position indication is indicated with no possible doubt of correct identification
2. Notification of the aircraft’s discrete SSR code or aircraft address
3. Notification that the aircraft is SSR Mode S / ADS-B-equipped with an aircraft identification feature when SSR Mode S coverage is available
4. Notification that the aircraft is ADS-B-equipped with an aircraft identification feature when compatible ADS-B coverage is available
5. Direct designation (pointing with the finger) of the position indication, if the two situation displays are adjacent or if a common “conference” type of situation display is used
6. Designation of the position indication by reference to bearing and distance from a geographical position or nav facility, together with the track of the observed position indication if the route of the aircraft is not known to both controllers
7. Instructing an aircraft to change SSR code by the transferring controller and the observation of the change by the accepting controller
8. Issuance of an instruction to the aircraft by the transferring controller to ‘squawk IDENT’ and observation of this response by the accepting controller

Question 19

When should an A/C be informed of its position? (5)

Answer 19

1. Upon identification, except when the identification is established:

• Based on the pilot’s report of the aircraft position
• Within 1nm of the runway upon departure (and the observed position on the situation display is consistent with the aircraft’s time of departure
• By use of either ADS-B / SSR Mode S aircraft ident or assigned discrete SSR codes and the location of the position indication is consistent with the CPL of the aircraft
• By transfer of identification

2. When the pilot requests this info
3. When a pilot’s estimate differs significantly from the controller’s estimate based on the observed position
4. When the pilot is instructed to resume own navigation after vectoring if the current instructions had diverted the aircraft from a previously assigned route
5. Immediately before termination of ATS surveillance service, if the aircraft is observed to deviate from its intended route

Question 20

What type of position information shall be passed to A/C? (5)

Answer 20

1. As a well-known geographical position
2. Magnetic track and distance to a significant point, an en-route navigation aid, or an approach aid
3. Direction (using points of the compass) and distance from a known position
4. Distance to touchdown, if the aircraft is on final approach
5. Distance and direction from the centre line of an ATS route