Basic Written

Question 0

According to MATS 1 what are the meaning of the following standard speech abbreviations:

Acknowledge
Freecall
Roger
Correction
Negative
Contact

Answer 0

Acknowledge
Let me know that you have received and understood this message

Freecall
Call (unit) Your details have not been passed

Roger
I have received all your last instruction. Under no circumstances to be used in reply to a question requiring a direct answer in the affirmative (Affirm) or negative (Negative)

Correction
An error has been made in this transmission (or message indicated). The correct version is…..

Negative
No, or permission not granted, or that is not correct or not capable

Contact
Establish communications with…. (your details have been passed)

Question 1

As detailed in MATS 2 name all the airfields (including the 4 letter designator) contained within or on the boundary of the Tyne sector

Answer 1

Airfield Designator Airfield Name
EGGL Lissett
EGGS Seaton
EGMB Blyton
EGMP Polebrook
EGVM Metfield
EGXL Longtown

Question 2

According to MATS 1 between which flights shall standard separation (vertical or horizontal) be provided? Do not include arrangements for aircraft in classes F and G airspace.

Answer 2

Standard vertical or horizontal separation shall be provided, unless otherwise specified, between:

a) All flights in Class A airspace;
b) IFR flights in Class C, D and E airspace;
c) IFR flights and VFR flights in Class C airspace;
d) IFR flights and Special VFR flights;
e) Special VFR flights.

Question 3

As detailed in MATS 2 state the vertical sectorisation (upper and lower limits) and frequencies of the following sectors:

Chiltern
Fisher High
Fisher Low
Medway TC
Medway Upper
Peaks
Wight Low
Wight Upper

Answer 3

Sector Upper & Lower Limits Frequency
Chiltern FL175 - 255 132.600
Fisher High FL 305+ 132.050
Fisher Low DB - FL305 135.650
Medway TC DB - FL175 123.900
Medway Upper FL255 - 660 130.875
Peaks DB - FL660 131.200
Wight Low DB - FL255 128.275
Wight Upper FL255 - 660 134.450

Question 4

As detailed in MATS 2 and the lesson handout what classes of airspace exist in the Tyne sector? Include where these different classes of airspace exist.

Answer 4

Class A - Airways below FL195
Class C - All airspace above FL195
Class D - Seaton CTR/CTA
Class G - All airspace below FL195 outside controlled airspace

Question 5

As listed in the AIP state what the following SSR codes signify:

0023
0030
0033
0037
1177
2000
7000
7007
7500
7600
7700

Answer 5

Code Meaning
0023 Aircraft engaged in actual SAR ops
0030 FIR lost
0033 Aircraft Para dropping
0037 Royal flight - helicopter
1177 Aircraft in receipt of FIS from”London AC
(Swanwick) FIS”
2000 Aircraft from non SSR environment
7000 Conspicuity code
7007 Open skies observation aircraft
7500 Hi-jack (unlawful interference)
7600 Radio failure
7700 Emergency

Question 6

As listed in MATS 1 Appendix E list the 9 items of operationally significant information to which controllers must ensure they receive a read back during telephone and intercom coordination messages:

Answer 6

Levels
Headings
Speed Restrictions
Airways or route instructions
Runway in use
SSR Codes
Pressure Settings, including units when value is below 1000hPa
Frequencies
Release and contact points

Question 7

According to MATS 1 how is lateral separation applied and how is it achieved?

Answer 7

Lateral separation shall be applied so that the distance between aircraft is never less than a specified amount. It is achieved by requiring aircraft to fly on different tracks or in different geographical locations as determined by visual observations or by use of navigational aids.

Question 8

According to MATS 1 how is longitudinal separation applied and how is it achieved?

Answer 8

Longitudinal separation based on either time or distance shall be applied so that the spacing between the estimated positions of the aircraft being separated is never less than a prescribed minima. It is achieved by requiring aircraft to:

a) Depart at a specified time;
b) Lose or gain time to arrive at a geographical location at a specified time; or
c) Hold over a geographical location until a specified time.

Question 9

As stated in MATS 1, describe the circumstances when pilots should and may be informed of their position.

Answer 9

A pilot is to be informed as soon as his aircraft has been identified. When operating inside controlled airspace, the pilot of an aircraft need only be so informed if the identification is achieved by the turn method.

Question 10

As stated in MATS 1 Appendix E, what items contained in RTF messages, from an area control perspective, are required to be read back in full?

Answer 10

Level Instructions
Heading Instructions
Speed Instructions
Airways or Route Clearances
SSR Operating Instructions
Altimeter Settings, including units when value is below 1000hPa
Runway in Use
Type of ATS
Frequency Changes

Question 11

Define the term “exact reporting point” according to MATS 1.

Answer 11

An “exact reporting point” is a position established by a navigational facility which is:

⚫Overhead a VOR
⚫Overhead an NDB
⚫A position notified as a reporting point and which is established by the intersection of VOR radials, or of a VOR radial and a bearing from an NDB
⚫A position established by a VOR radial combined with a range from a co-located or associated DME

Question 12

As stated in MATS 1 under what circumstances may a controller consider a Mode A code to be deemed validated?

Answer 12

Controllers may deem Mode A codes to be validated when it can be ascertained from the Code Assignment Plan that an observed Mode A code has been assigned by a unit capable of validating the code, unless:

a) The code is promulgated as being unvalidated; or
b) The controller has been notified that the code is corrupt.

Question 13

According to MATS 1 what may surveillance systems be used to provide, whether or not the aircraft has been identified?

Answer 13

Surveillance systems may also be used to provide the following, whether or not the aircraft has been identified:

a) Information on the position of aircraft likely to constitute a hazard
b) Avoiding action
c) Information about observed weather for pilots and other controllers
d) Assistance to aircraft in an emergency

Question 14

As described in MATS 1 when is it not necessary to inform the pilot of an aircraft that the identification of his aircraft is lost.

Answer 14

When using SSR, controllers may be temporarily unable to read the data blocks associated with aircraft due to overlapping or garbling e.g. in holding areas. Although this constitutes a loss of identification, the pilot need not be advised that identification has been lost if the controller anticipates that identification will be re-established immediately the overlapping or garbling ceases.

Question 15

What are the vertical separation minima as described in MATS 1?

Answer 15

The vertical separation minima are:

a) Between aircraft flying subsonic:

Up to FL 290 apply 1000 feet;
Above FL290 apply 2000 feet;
Except that between FL290 and FL410 inclusive, 1000 feet may be applied between RVSM approved aircraft operating in airspace designated as being notified for the application of this separation standard.

b) Between aircraft flying supersonic, and between aircraft flying supersonic and aircraft flying subsonic:

Up to FL450 = 2000 feet;
Above FL 450 = 4000 feet.

Question 16

As described in MATS 1, detail how position information shall be passed to aircraft.

Answer 16

Position information shall be passed in one of the following forms:

a) A well known geographical position;
b) Bearing (using points of the compass) and distance from a known position;
c) Magnetic track and distance to a location displayed on the situation display that is a reporting point, an en route navigational aid, or an approach aid;
d) Latitude and Longitude (by specific units only when authorised in MATS Part 2); or
e) Distance from touchdown if the aircraft is on final approach.

Question 17

As detailed in MATS 1 describe the departing aircraft method of identification.

Answer 17

By observing and correlating the Position Indication of a departing aircraft to a known airborne time. Identification is to be achieved within one mile of the end of the runway unless otherwise authorised by the CAA.

Particular care should be taken to avoid confusion with aircraft overflying the aerodrome, making a missed approach, departing from an adjacent runway or holding overhead the aerodrome.

Question 18

According to MATS 1:

i) What is the purpose of an ATC clearance, how are such clearances based and when are they required? Do not go into detail with regards to the manoeuvring area and vehicular traffic
ii) What items shall be included in an ATC clearance and what items are to be added as necessary?

Answer 18

i) An ATC clearance authorises an aircraft to proceed under conditions specified by an ATC unit. Clearances are based solely on known traffic conditions and are required for any flight, or portion of a flight, which is provided with an ATC or advisory service.
ii) An ATC clearance shall include the following items:

⚫Aircraft identification
⚫Clearance limit
⚫Route
⚫Levels of flight and changes of levels

The following items are to be added to a clearance as necessary:

⚫ATFM slot
⚫Time restrictions
⚫Communications instructions
⚫Any special instructs e.g. approach and departures manoeuvres

Question 19

According to MATS 1, what is the standard phraseology for traffic information on known traffic?

Answer 19

Traffic (number) o’clock (distance) miles opposite direction/crossing left to right/right to left (number) thousand feet above/below

Question 20

According to MATS 1, what is the correct phraseology for “avoiding action” in the lateral plane?

Answer 20

(A/c identity) avoiding action, turn left/right immediately heading (three digits) traffic ([left/right] number) o’clock (distance) miles opposite direction/crossing left to right/right to left (level information)

Question 21

In the context of applying longitudinal separation, define the following terms as per MATS 1:

a) Same track
b) Reciprocal track
c) Crossing track

Answer 21

a) When the track of one aircraft is separated from the track of the other by less than 45*
b) When the track of one aircraft is separated from the reciprocal of the other by less than 45*
c) Intersecting tracks which are not classed as “same” or “reciprocal”

Question 22

According to MATS 1:

a) How are cruising levels normally allocated to aircraft with reference to flight planned levels and priorities?
b) What level must not be allocated?

Answer 22

a) Normally, the cruising level requested in the flight plan is to be allocated. If the flight planned level is not available, the nearest appropriate vacant level is to be allocated

When two or more aircraft are at the same cruising level, the preceding aircraft shall normally have priority.

An aircraft at a cruising level shall normally have priority over other aircraft requesting that level.

b) FL195 must not be allocated as a cruising level.

Question 23

As detailed in MATS 2 list all the reporting points in the correct order that an aircraft would fly over on the following routes. Include the reporting point immediately preceding the Tyne sector and the first reporting point after the aircraft has left the Tyne sector.

L17
L17/T45
T45
L173
L17/L173
T45/L173
T45/L17
UY96

Answer 23

L17 SEV-DAR-TYN-OLIVE
L17/T45 SEV-DAR-TYN-SWALO-RYE
T45 CHE-SHARK-PEWSI-TYN-SWALO-RYE
L173 HAYLE-STONE-PEWSI-CHARD-TAV-TEMMS
L17/L173 SEV-DAR-TYN-STONE-HAYLE
T45/L173 RYE-SWALO-TYN-CHARD-TAV-TEMMS
T45/L17 CHE-SHARK-PEWSI-TYN-OLIVE
UY96 SWIFT-TYN-STONE-HAYLE

Question 24

As given in MATS 1, state the definition of the following, together with explanations:

a) Transition Altitude
b) Transition Level

Answer 24

a) Transition altitude is the altitude at or below which the vertical position of an aircraft is normally controlled by reference to altitude. Wherever possible there is a common transition altitude for aerodromes within a control zone. Unless otherwise notified the transition altitude for civil aerodromes is 3000 feet.
b) Transition level is the lowest flight level available for use above the transition altitude. It is determined from the table in Appendix A as follows:

i) Within controlled airspace by the controlling authority and it will normally be based on the QNH of the major aerodrome
ii) Outside controlled airspace by the Aerodrome Operator and based on the aerodrome QNH

Question 25

According to MATS 1, what are the instructions and considerations relating to the amendments to clearances? Do not include references to SID profiles/routes.

Answer 25

When an amendment is made to a clearance the new clearance shall be read in full to the pilot and shall automatically cancel any previous clearance. Controllers must be aware, therefore, that if the original clearance included a restriction e.g. “cross ABC FL150 or below” then the issue of a revised clearance automatically cancels the earlier restriction, unless it is reiterated with the revised clearance.

Question 26

As stated in MATS 1:

i) What do surveillance services comprise of?
ii) What shall a controller do before providing any of the above services, and what does this action not imply?

Answer 26

i) Surveillance services comprise:

a) Separation of arriving, departing and en route traffic;
b) Vectoring;
c) Position information to assist in the navigation of aircraft;
d) Monitoring traffic to provide information to the procedural controller;
e) Assistance to aircraft crossing controlled airspace.

ii) Before a controller provides any of the above services he shall either:

a) Identify the aircraft, using a method appropriate to the surveillance system in use; or
b) Have had the identity of the aircraft transferred from another controller.

The act of identifying an aircraft does not imply that a surveillance service is being given.

Question 27

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 not known.

Answer 27

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:

a) They are under his control;
b) They have been coordinated;
c) They are operating in accordance with established agreements.

Question 28

According to MATS 1:

a) How are Mode C responses used to assess vertical separation?
b) When can Mode C not be used to apply vertical separation?
c) What conditions apply to the use of Mode C for minimum vertical separation?
d) For both aircraft under a Radar Control Service and aircraft under a Deconfliction Service, what are the vertical separation conditions if aircraft intentions are not known and/or if Mode C is unverified?

Answer 28

a) 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.
b) Vertical separation using Mode C is not applied against aircraft transponding A0000.
c) 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:

i) They are under his control;
ii) They have been coordinated; or
iii) They are operating in accordance with established agreements.

d) Aircraft under Radar Control Service:

If the intentions of Mode C transponding aircraft are not known, the minimum separation must be increased to 5000 feet. Unverified Mode C data may be used for separation purposes provided a minimum vertical separation of 5000 feet is maintained and radar returns, however presented, are not allowed to merge.

Aircraft under Deconfliction Service:

If the intentions of the Mode C transponding aircraft are not known , the vertical deconfliction minima must be increased to 3000 feet, and unless the SSR Mode 3A indicates that the Mode C data has been verified, the surveillance returns, however presented, should not merge.

Question 29

According to MATS Part 1, when:

i) May a pilot file a flight plan?
ii) Must a pilot file a flight plan?
iii) Is a pilot advised to file a flight plan?

Answer 29

i) A pilot may file a flight plan for any flight.

ii) a pilot is required to file a flight plan:
a) For all flights within controlled airspace, which are conducted in accordance with IFR;
b) For flights within Class C and D airspace conducted in accordance with VFR;
c) When he wishes to receive an ATAS (Class F airspace);
d) For all flights which will cross a UK international FIR boundary;
e) For any flight where the destination is more than 40km from the aerodrome of departure and the aircraft’s maximum total weight authorised exceeds 5700kg.

iii) A pilot is advised to file a flight plan:
a) If his flight involves flying over the sea more than 10miles from the UK coast or flying over sparsely populated areas where SAR operations would be difficult; or
b) If he intends to fly into an area in which SAR operations are in progress. The flight plan should include the expected times of entering and leaving the area and the details must also be passed to the parent ACC. The ACC is to notify the ARCC concerned.

Question 30

As detailed in MATS 1:

i) Define the term clearance limit and how it can be specified
ii) When shall an aircraft be cleared for its entire route and what is the clearance limit when this is not possible?

Answer 30

i) A clearance limit is the point to which an aircraft is granted an ATC clearance and shall be specified by naming:

a) An aerodrome;
b) A reporting point; or
c) A controlled or advisory airspace boundary.

ii) An aircraft shall be cleared for the entire route to the aerodrome of first intended landing when:
a) It has planned to remain within controlled or advisory airspace throughout the flight; and
b) There is reasonable assurance that prior coordination will be effected ahead of the passage of the aircraft.

The clearance limit for all other flights shall be the boundary of controlled or advisory airspace.

Question 31

As stated in MATS 1, what is a loss of separation and what are a controller’s actions when faced with this situation?

Answer 31

If, for any reason, a controller is faced with a situation in which two or more aircraft are separated by less than the prescribed minima, e.g. ATC errors or differences in the pilot’s estimated and actual times over reporting points, he is to:

a) Use every means at his disposal to obtain the required minimum with the least possible delay; and
b) When considered practicable, pass traffic information if an ATS surveillance service is being provided, otherwise pass essential traffic information.

Question 32

According to MATS 1:

a) When are pilots to make position reports, and what additional information may these reports contain?
b) When are controllers to instruct pilots to make position reports?

Answer 32

a) In order to reduce RTF communication, a pilot will make a position report only:

i) On first transfer of communication from another ACC or sector. This report will contain aircraft identification and flight level only. Subsequent reports will contain aircraft identification, position and time;
ii) On reaching the limit of the ATC clearance;
iii) When instructed to by ATC.

b) Controllers are to instruct pilots to make position reports:

i) When the aircraft is outside ATS surveillance system cover;
ii) Before identification has been achieved; and
iii) As detailed in MATS Part 2.

Question 33

a) What is coordination and when is it affected? Give any provisos for responsibility.
b) What conditions and/or precautions need to be taken into account when agreeing coordination between controllers or on behalf of another controller?

Answer 33

a) Coordination is the act of negotiation between 2 or more parties each vested with the authority to make executive decisions appropriate to the task being discharged. Coordination is effected when the parties concerned, on the basis of known intelligence, agree a course of action. Responsibility for obtaining the agreement and for ensuring implementation of the agreed course of action may be vested in one of the controllers involved.
b) A controller may carry out coordination on behalf of another controller, provided that the traffic situation and time available are such that the controller being represented can put into effect any agreed action

Question 34

According to MATS:

a) Define Essential Traffic Information
b) When passed to an aircraft, what shall it include?

Answer 34

Essential traffic is traffic which is separated for any period by less than the specified standard separation. It is normally passed in situations when ATS surveillance systems are not available.

Essential traffic information passed to an aircraft shall include:

a) Direction of flight of conflicting aircraft;
b) Type of conflicting aircraft;
c) Cruising level of conflicting aircraft and ETA for the reporting point, or for aircraft passing through the level of another with less than the normal separation; the ETA for the reporting point nearest to where the aircraft will cross levels; and
d) Any alternative clearance.

Question 35

According to MATS 1 when:

i) Shall standard separation be increased?
ii) May standard separation be reduced? (Ignore in the vicinity of aerodromes)

Answer 35

i) Separation standards are minima and shall be increased when:

a) Requested by the pilot
b) A controller considers it necessary
c) Directed by the CAA

ii) In addition to the following paragraphs, standard separation may be reduced when authorised by the CAA and published in MATS Part 2.

Standard separation may be reduced when a SAR aircraft is escorting an aircraft in an emergency. A minimum is not laid down in UK FIRs and separation may be reduced to that which can be maintained visually or with airborne radar.

Reduced vertical separation may be applied during surveillance system failure as detailed in Section 1 Chapter 5, paragraph 20.

Question 36

According to MATS 1:

a) As described in MATS 1, what fundamental coordination requirement between ACCs or sectors is laid down for aircraft receiving an ATC or advisory service? Include details of responsibility for initiation of coordination.
b) As stated in MATS 1, which information must be recoordinated if changes occur and by when?

Answer 36

a) Aircraft receiving an ATC or advisory service from one ACC or sector must not be permitted to penetrate the airspace of another ACC or sector unless prior coordination has taken place. The responsibility for initiating coordination rests with the controller of the unit or sector transferring control, who shall comply with any conditions specified by the accepting controller.
b) Subsequent changes in flight level, routing or revisions of 3 minutes or more are to be recoordinated by the transferring controller and agreement reached before transfer of communication takes place.

Question 37

As detailed in MATS 1 describe the turn method of establishing identification. Include any conditions and precautions to be taken. (19)

Answer 37

An aircraft may be identified by ascertaining its heading and, following a period of track observation, correlating the observed movement of a particular Position Indication with:

⚫The acknowledged execution of an instruction to alter heading by at least 30*;

⚫One or more changes of heading of at least 30*, as instructed by another controller;

⚫One or more changes of heading of at least 30* reported by the pilot.

A turn for identification does not constitute the provision of a surveillance service. However, controllers should take into consideration terrain, other surveillance returns, PSR coverage and the RoA before instructing an aircraft to alter heading.

In using the turn method the controller shall:

⚫Verify that the movements of not more than one Position Indication correspond with those of the aircraft;

⚫Exercise caution particularly when employing this method in areas where changes of aircraft heading are commonly made as navigational routine.

Question 38

State the minimum time separations (as specified in MATS 1) that may be used between aircraft at the same cruising level and on the same track, and detail any associated provisions. (14)

Answer 38

2 minutes Provided the 2 minute departure separation has been applied (see
separate table)

3 minutes When specifically authorised by the CAA provided both aircraft
are:
i) Equipped with functioning transponders; and
ii) Continuously monitored by radar and the actual distance
between them is never less than 20 miles

5 minutes Provided the preceding aircraft has filed an airspeed of 20 knots
or more faster than the following aircraft

5 minutes When specifically authorised by the CAA, provided both aircraft
are:
i) Equipped with functioning transponders; and
ii) Monitored by radar and the actual distance between them is
never less than 30 miles

10 minutes All others

Question 39

According to MATS 1, detail the types of Air Traffic Services which can be provided according to the class of airspace within which the aircraft is flying. Include the remarks relevant to aircraft compliance with ATC instructions. (14)

Answer 39

Airspace Services Provided Remarks

Class A to E ⚫ Air Traffic Control service Aircraft are required to
(Controlled) with or without surveillance comply with air traffic
⚫ Alerting Service control instructions

Class F Participating Traffic: Instructions issued by
(Advisory) ⚫ Procedural Service or controllers to pilots
⚫ Deconfliction Service operating outside
⚫ Alerting Service controlled airspace are
not mandatory
Non Participating Traffic: HOWEVER
⚫ Procedural Service or The services rely upon
⚫ Deconfliction Service or pilot compliance with the
⚫ Traffic Service or specified terms and
⚫ Basic Service conditions so as to
⚫ Alerting Service promote a safer
operating environment
for all airspace users

Class G ⚫ Procedural Service or Instructions issued by
⚫ Deconfliction Service or controllers to pilots
⚫ Traffic Service or operating outside
⚫ Basic Service controlled airspace are
⚫ Alerting Service not mandatory
HOWEVER
The services rely upon
pilot compliance with the
specified terms and
conditions so as to
promote a safer
operating environment
for all airspace users

Question 40

According to the AIP, what are the pilot’s responsibilities and actions when an aircraft transponder fails before intended departure and cannot be repaired? Include ATC considerations in your answer, but not the temporary failure of Mode C alone. (8)

Answer 40

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, including unserviceability of any Mode S functionality, as specified in ICAO Doc 4444, Appendix 2.

Question 41

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 pilots responsibilities where appropriate, but not the temporary failure of Mode C alone. (7)

Answer 41

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 provisions in paragraph 4.1.1 apply.

Question 42

According to MATS 1:

a) Give full details of the methods that may be used to achieve coordination
b) When is coordination deemed to have been achieved? (16)

Answer 42

a) Coordination may be achieved by one of the following methods:

⚫Tactical Coordination

The coordination of individual aircraft to which the coordinating controllers are providing, or are about to provide, an ATS. It is achieved either verbally (face to face or over a landline) or silently using an electronic data communications system. Silent coordination procedures are to be detailed in MATS 2 and Unit Military Procedures.

⚫ Standing Coordination

Coordination which is implemented automatically, on a permanent basis, without communication between the controllers involved. It is effected in accordance with a written agreement between the units or sectors involved, and is only valid for the aircraft and circumstances specified in the MATS 2.

b) When approved by the CAA, coordination is deemed to have been achieved if an estimated message has been passed and the accepting ATC unit has raised no objection.

Question 43

As stated in MATS 1, describe the different types of Mode A codes that controllers are to adding to aircraft, as detailed in the Code Assignment Plan. Include in your answer the actions of controllers at SSR equipped units when allocating such a code. (9)

Answer 43

Controllers are to assign Mode A codes to aircraft according to the Code Assignment Plan, which comprises:

a) Discrete codes comprising:
i) Domestic codes which are assigned to aircraft flying within the areas of responsibility of a unit;
ii) ORCAM codes which are assigned to international flights and will normally be retained beyond the area of responsibility of the assigning unit.

b) Special purpose codes allocated internationally.
c) Conspicuity codes, allocated nationally, or to specific users/units.

When providing a surveillance service to an aircraft, controllers operating at SSR equipped units should allocate that flight with a discrete code in accordance with the SSR assignment plan. Unless otherwise directed by an ATC unit, Mode C will be selected in conjunction with Mode A. Controllers must, therefore, verify the accuracy of the Mode C readout when assigning discrete codes to aircraft.

Question 44

Listed below are various types of flight as stated in MATS 1. List the Flight Priority for each (note some may be duplicated). (11)

Answer 44

Category A:

⚫ Aircraft in emergency (e.g. engine fault, fuel shortage, seriously ill passenger)
⚫ Aircraft which have declared a “Police Emergency”
⚫ Ambulance/Medical aircraft when the safety of life is involved

Category B:

⚫ Flights operating for search and rescue or other humanitarian reasons
⚫ Post-accident flight checks
⚫ Other flights, including Open Skies Flights, authorised by the CAA
⚫ Police flights under normal operational priority

Category C:

⚫ Royal Flights
⚫ Flights carrying visiting Heads of State which have been notified by NOTAM/temporary supplement

Category D:

⚫ Flights notified by the CAA carrying Heads of Government or very senior government ministers

Category E:

⚫ Flight check aircraft engaged on, or in transit to, time or weather critical calibration flights
⚫ Other flights authorised by the CAA

Normal Flights:

⚫ Flights which have filed a flight plan in the normal way and conforming with normal routing procedures
⚫ Initial instrument flight tests conducted by the CAA Flight Examining Unit (RTF callsign “EXAM”)

Category Z:

⚫ Training, non-standard and other flights

Question 45

As a radar controller, what would be your actions in the events of a surveillance system failure, according to MATS 1? Do not detail the return to service of a previously failed system. (5)

Answer 45

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 1000 feet vertical separation and 1000 feet where a controller would normally apply 2000 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.

Question 46

As specified in MATS 1 under what conditions may an aircraft be instructed to climb or descend to a level previously occupied by another aircraft? Include any precautions. (12)

Answer 46

An aircraft may be instructed to climb or descend to a level previously occupied by another aircraft provided that:

a) Vertical separation already exists;
b) The vacating aircraft is proceeding to a level that will maintain vertical separation; and

c) Either:
i) The controller observes that the vacating aircraft has left the level; or
ii) The pilot has reported vacating the level

If severe turbulence is known to exist, instructions shall be delayed until the vacating aircraft is known to be at, or through, another level separated by the required minimum.

Controllers shall exercise caution when instructing an aircraft to climb or descend to a previously occupied level. Consideration shall be given to the fact that aircraft may climb or descend at markedly different rates and, if necessary, additional measures such as specifying a maximum or minimum climb or decent rate for each aircraft shall be applied to ensure that the required separation is maintained. This is particularly relevant when the aircraft concerned are established in the same holding pattern.

Question 47

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. (14)

Answer 47

The following criteria apply when assessing the vertical position of a Mode C transponding aircraft:

a) 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;
b) 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;
c) 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;
d) 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.

Question 48

According to MATS 1:

a) How are Mode C responses used to assess vertical separation?
b) When can Mode C not be used to apply vertical separation?
c) What conditions apply to the use of Mode C for minimum vertical separation?
d) For both aircraft under a radar control service and aircraft under a deconfliction service, what are the vertical separation conditions if aircraft intentions are not known/or if Mode C is unverified? (14)

Answer 48

a) 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.
b) Vertical separation using Mode C is not applied against aircraft transponding A0000.
c) The following criteria apply when assessing the vertical position of a Mode C transponding aircraft:
i) 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;
ii) 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;
iii) 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;
iv) 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.

d) Aircraft under radar control service:
If the intentions of Mode C transponding aircraft are not known, the minimum separation must be increased to 5000 feet. Unverified Mode C data may be used for separation purposes provided a minimum vertical separation of 5000 feet is maintained and radar returns, however presented, are not allowed to merge.

Aircraft under a deconfliction service:
If the intentions of the Mode C transponding aircraft are not known, the vertical deconfliction minima must be increased to 3000 feet, and unless the SSR Mode 3A indicates that the Mode C data has been verified, the surveillance returns, however presented, should not merge.

Question 49

As stated in MATS 1, fully describe the method of identification using SSR and when such methods are to be used. Include any precautions to be taken. (9)

Answer 49

When using Mode A to identify aircraft, one of the following methods is to be employed:

a) Observing 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 aircraft callsign. When code/callsign conversion procedures are in use and 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 SPI transmissions within the same area may result in misidentification. Aircraft displaying the conspicuity code 7000 are not to be identified by this method