Section 3, Chapter 1 - Approach Control

Question 1

What types of Approach Control Services are provided within the UK FIRs and how do they vary by airspace classification?

Answer 1

Approach Control Services within the UK FIRs consist of surveillance and non-surveillance based ATS. The type of ATS provided depends on the airspace classification:

• Class A, C, D: Air Traffic Control Service (with or without surveillance) and Alerting Service. Aircraft must comply with air traffic control instructions.
• Class E: Air Traffic Control Service (with or without surveillance) to IFR flights and Alerting Service; Traffic or Basic Service and Alerting Service to participating VFR flights. Participating VFR flights receive UK FIS in accordance with CAP 774.
• Class G: Procedural Service, Deconfliction Service, Traffic Service, Basic Service, and Alerting Service. Participating flights receive UK FIS in accordance with CAP 774.

Additionally, an Approach Control unit may be combined with an Aerodrome Control unit or a Zone Control unit, or share the Zone Control function with an Area Control unit.

Question 2

What ATC Services are provided by an Approach Control unit at an aerodrome within controlled airspace?

Answer 2

An Approach Control unit at an aerodrome within controlled airspace provides ATC Services to aircraft according to the classification of the airspace, under the following conditions:

• Arriving Aircraft: From the time and place at which they are released by Area Control until control is transferred to Aerodrome Control.
• Approaching Aircraft from Outside Controlled Airspace: From the time they place themselves under Approach Control until control is transferred to Aerodrome Control.
• Departing Aircraft: From the time they are taken over from Aerodrome Control until:
• They are transferred to Area Control, or
• They are clear of controlled airspace.
• Overflying Aircraft: When they are within the relevant controlled airspace.

Additionally, Approach Control shall:
* Provide standard separation between Special VFR and IFR flights and between Special VFR flights unless reduced separation is approved by the CAA.
* Provide participating VFR flights in Class E airspace with either Traffic Service or Basic Service, subject to controller workload, in accordance with CAP 774 – UK Flight Information Services.

Question 3

What ATS are provided by an Approach Control unit at an aerodrome outside controlled airspace?

Answer 3

An Approach Control unit at an aerodrome outside controlled airspace provides ATS to aircraft as determined by the Aerodrome Operator and approved by the CAA under the following conditions:

• Arriving Aircraft: From the time and place they place themselves under Approach Control until control is transferred to Aerodrome Control.
• Departing Aircraft: From the time they are taken over from Aerodrome Control until they no longer wish to receive a service or are 10 minutes flying time away from the aerodrome, whichever comes first.
• Overflying Aircraft: From the time they place themselves under Approach Control until they are clear of the approach pattern and either no longer wish to receive a service or are 10 minutes flying time away from the aerodrome, whichever comes first.

Additionally:
* Aircraft within an Aerodrome Traffic Zone (ATZ) must comply with instructions from the ATC unit.
* IFR/VFR flight within Class F/G airspace outside the ATZ is permitted without an ATC clearance, but controllers will act on the assumption that pilots will comply fully with their instructions to ensure a safer operating environment for all airspace users.

Question 4

What type of flight information is provided to aircraft by Approach Control?

Answer 4

Approach Control provides flight information to aircraft under its control, especially regarding any failure or irregular functioning of the aerodrome lighting system or approach aid.

Question 5

What information does Approach Control provide to Aerodrome Control?

Answer 5

Approach Control provides the following information to Aerodrome Control:
* Pertinent data on all relevant flights, including the type of flight (IFR or VFR), the level of arriving aircraft, and ETA.
* The anticipated order in which control of aircraft is to be transferred.
* The anticipated delay to departing IFR flights along with the reason for the delay.

Question 6

What information does the approach controller provide to the approach surveillance controller?

Answer 6

The approach controller provides the following information to the approach surveillance controller as required:

• The current weather report, including Runway Visual Range (RVR).
• Any other significant information, such as aerodrome and lighting unserviceabilities, runway changes, etc.

Question 7

What information does Approach Control provide to Area Control regarding IFR flights?

Answer 7

Approach Control provides the following data on IFR flights to Area Control:

• Lowest level at the holding facility available for use by Area Control.
• The average time interval between successive approaches.
• Revisions of expected approach times issued by Area Control when Approach Control calculations show a variation of 5 minutes or more.
• Arrival times over the holding point if these vary from the estimate by 3 minutes or more.
• Missed approaches when re-routing is entailed, to ensure subsequent action is coordinated.
• Departure times of aircraft.
• All available information relating to overdue aircraft.

Note: Any of these items can be deleted from routine practice by agreement with Area Control.

Question 8

What co-ordination occurs between Approach Control and Aerodrome Control?

Answer 8

Approach Control coordinates with Aerodrome Control:

• Aircraft approaching to land, requesting clearance if necessary.
• Arriving aircraft to be cleared to visual holding points.
• Aircraft routeing through the traffic circuit.

Aerodrome Control coordinates with Approach Control:

• Departing IFR flights.
• Arriving aircraft making their first call on the tower frequency, unless transferred to Approach Control.

Question 9

What co-ordination is required between Area Control and Approach Control for arriving aircraft?

Answer 9

Area Control must co-ordinate with Approach Control for arriving aircraft that need to be cleared to an aerodrome holding facility or a visual holding point, instead of the normal holding facility.

Question 10

Under what circumstances may IFR flights operating with visual reference to the surface be transferred by Approach Control to Aerodrome Control?

Answer 10

IFR flights operating with visual reference to the surface may be transferred by Approach Control to Aerodrome Control in the following circumstances:

1. When an aircraft carrying out an instrument approach has become ‘number 1 to land’, and for following aircraft when they are established on final approach and have been provided with the appropriate separation from preceding aircraft.
2. Aircraft operating in the traffic circuit.
3. Aircraft approaching visually below all cloud when the reported aerodrome visibility is 10 km or more. When the reported visibility consists of two values, the lower value shall be used to determine whether an aircraft may be transferred.

Note: For cases 2 and 3, the volume of traffic and Aerodrome Control workload must allow the use of one of the reduced separations permitted in the vicinity of aerodromes. To clear other aircraft to descend through the cloud formation, it is necessary for the aircraft approaching underneath to be kept more than 1,000 ft below all cloud, or for horizontal separation to be provided.

Question 11

What information must be supplied when Approach Control delegates its functions to Approach Surveillance Control?

Answer 11

When Approach Control delegates its functions to Approach Surveillance Control, the following information must be supplied:

• Callsign, type, level, route, ETA (or position), and frequency.
• Expected approach time, if appropriate.
• Service required.
• Release and contact instructions issued by Area Control.
• Information on conflicting traffic.
• Actual time of departure of outbound aircraft.

Note: Approach Control may also delegate the responsibility for co-ordination to Approach Surveillance Control.

Question 12

Under what conditions may Approach Control delegate its functions to Aerodrome Control for IFR flights?

Answer 12

At certain aerodromes, Approach Control may delegate its functions to Aerodrome Control for certain categories of IFR flights operating in the vicinity of the aerodrome, provided the aerodrome controller holds a valid Approach Control rating for that aerodrome. The details of the extent of the permitted delegation will be published in MATS Part 2.

Question 13

When may Approach Control instruct IFR flights to establish communication with Aerodrome Control, and what are the limitations?

Answer 13

Approach Control may instruct IFR flights to establish communication with Aerodrome Control for landing clearance and essential aerodrome information when the aircraft has become number one to approach, and for following aircraft, when they are established on final approach and have been provided with appropriate separation.

Until such aircraft are flying with visual reference to the surface, the responsibility for separation between them remains with Approach Control. Aerodrome Control shall not issue any instructions or advice that would reduce the separation established by Approach Control.

Question 14

What procedures does Approach Control follow for VFR flights?

Answer 14

Approach Control follows these procedures for VFR flights:

Control and Coordination:

• Retain control of arriving VFR flights until traffic information on IFR and other VFR flights is provided and coordination with Aerodrome Control is completed.
• Ensure VFR flights are transferred in time for Aerodrome Control to provide additional local traffic information.

Monitoring and Advising:

• Watch for VFR flights approaching sectors with aircraft on instrument approaches or where sequencing is active.
• Avoid giving VFR flights clearance for straight-in approaches in such cases and advise pilots to avoid initial and final approach areas.

Use of Visual Reference Points (VRPs):

• VRPs assist in routing VFR traffic and integrating with IFR flights.
• Controllers should not instruct holding over VRPs outside controlled airspace unless within controlled airspace where a known traffic environment exists.

Meteorological Conditions in Class D Airspace:

• If visibility drops below 5 km and/or cloud ceiling below 1500 ft, inform VFR pilots and request clearance type.
• Do not issue VFR clearances under these conditions except for specific helicopter operations (e.g., Police, HEMS, SAR) with valid exemptions.

Specific Notes:

• UK General Permission ORS4 No. 1477: Permits VFR flight at night.
• UK General Exemption ORS4 No. 1576: Exempts certain helicopter operations from specific requirements under low visibility conditions.
• UK General Exemption ORS4 No. 1577: Exempts certain inspection flights from specific requirements.
• Accredited Observers: Pilots with valid licenses or students with meteorology knowledge exams can act as observers for meteorological conditions.

Visibility Reporting:

• Use the lower value when reported visibility consists of two values to determine procedures.

Subsidiary Aerodromes:

• Procedures are detailed in MATS Part 2.

Question 15

What are the procedures for ensuring terrain clearance for arriving aircraft?

Answer 15

The procedures for ensuring terrain clearance for arriving aircraft are:

Initial Clearance Levels:

• The assigned level in initial clearances should normally not be below the appropriate minimum sector altitude or the highest minimum sector altitude if not known.
• If a pilot is flying at or has requested a lower level, or can accept a lower level ATC clearance, a reminder of the highest sector altitude should be issued.

Specific Route Altitudes:

• This instruction does not apply to routes with altitudes specifically approved by the CAA.

Clearance Relay by FIS Personnel:

• If clearance is relayed by FIS personnel at an ACC, the approach controller must include the minimum sector altitude in the clearance message.

Question 16

What are the procedures for releasing inbound aircraft from Area Control to Approach Control?

Answer 16

The procedures for releasing inbound aircraft from Area Control to Approach Control are:

Passing Estimates and Releasing Aircraft:

• Area Control shall pass estimates and release inbound aircraft to Approach Control.
• Inbound estimates should be passed at least 15 minutes prior to the aircraft’s arrival at the designated approach fix.

Release Messages:

• Release messages should be timely as specified in MATS Part 2 and include:
  1. Aircraft identity, type, and SSR code (if applicable).
  2. Point of departure.
  3. Release point.
  4. Estimated time and level at the holding facility, or arrival time and level at the holding facility if the release is given after arrival.
  5. Expected Approach Time (EAT).
  6. Contact point.

Clearance to Holding Facility:

• Area Control should clear arriving aircraft to the holding facility if remaining within airspace Classes A to F, and give holding instructions if necessary, including an EAT in the clearance.

Instructions by Approach Control:

• Approach Control may issue instructions to an aircraft released by Area Control, but the aircraft must not be instructed to climb above or stop its descent to the level at the holding point agreed with Area Control without prior coordination.

Release Restrictions:

• Unless approved by the CAA, Area Control shall not release arriving aircraft to Approach Control at FL195 or above. When approved, MATS Part 2 will detail the area and conditions under which these procedures may be used.

Alternative Clearance:

• After coordination, Area Control may clear an arriving aircraft to an aerodrome facility or a visual holding point instead of the normal holding facility.

Question 17

What is the procedure for controlling an aircraft subject to a ‘radar release’?

Answer 17

When an aircraft is subject to a ‘radar release’, the approach controller shall not control the aircraft until the approach radar controller reports that it is clear of the conflicting traffic.

Question 18

What are Aerodrome Operating Minima and what factors influence them?

Answer 18

Aerodrome Operating Minima are criteria used by pilots to determine whether they may land or take off from any runway at night or in Instrument Meteorological Conditions (IMC). They consist of:

Take-offs:

• Runway Visual Range (RVR) and/or visibility, and if necessary, cloud conditions.

Approach and Landings:

• Decision height or minimum descent height, RVR, and/or visibility, and if necessary, cloud conditions applicable for the type of approach.

Factors Influencing Aerodrome Operating Minima:

1. Type of aircraft and its navigation equipment.
2. Flight crew composition, competence, experience, and flight techniques used.
3. Runway dimensions and characteristics.
4. Availability and performance of visual and non-visual ground aids.
5. Obstacles in the approach, missed approach, and climb out areas.
6. Obstacle clearance height for the instrument procedures.
7. Means to determine and report meteorological conditions.
8. Special provisions pertinent to low visibility procedures.

Additional Note:
Controllers are not responsible for determining, passing, or enforcing a pilot’s Aerodrome Operating Minima, but should report any occurrences that could endanger an aircraft, its occupants, or any other person as specified in Section 6 Chapter 3.

Question 19

What information must Approach Control provide to arriving aircraft and keep them updated on?

Answer 19

Initial Information Provided by Approach Control:

After an arriving aircraft places itself under Approach Control, the following information must be passed as soon as practicable (except when ATIS is used):

• Runway in use.
• Current meteorological information with time of observation:
  1. Surface wind direction (magnetic) and speed, including maximum wind speed if 10 knots or more above mean, and extremes in direction if variation is 60 degrees or more and mean speed exceeds 3 knots.
  2. Visibility.
  3. Present weather.
  4. Significant cloud amount and height of base.
  5. Appropriate barometric pressure setting.
  6. Relevant information reported by other pilots (e.g., vertical wind shear, severe icing, severe turbulence).
  7. Significant meteorological information (e.g., thunderstorms, hail).
  8. Warnings of marked temperature inversion.
  9. Any other relevant information.
  10. RVR (Runway Visual Range) as per Chapter 3 procedures.
  11. Note: For VMC flights below cloud, information may be reduced to surface wind, barometric pressure setting, and significant pilot-reported information.
• Current runway surface conditions when appropriate.
• Any changes in the operational status of essential visual and non-visual aids for approach and landing.
• Low Visibility Procedures (LVP) in operation.

Updates Provided Until Landing:

• Significant changes in meteorological and runway conditions.
• Further reports from other pilots.
• Further changes in the operational status of approach and landing aids.
• Implementation or cancellation of LVP.

Question 20

What precautions should controllers take when approving self-positioning of aircraft to final approach?

Answer 20

Controllers should take the following precautions when approving self-positioning of aircraft to final approach:

• Exercise caution and avoid initiating reference to the ‘Centrefix’ or any other locally used term.
• If there is any doubt about the location of the ‘Centrefix’ or the position referred to by a pilot, ask the pilot to define this position and consider this definition when performing their controlling duties.

Question 21

What are the procedures for controllers when transmitting meteorological information to pilots?

Answer 21

Controllers must follow these procedures when transmitting meteorological information to pilots:

Conforming to Requests:

• Ensure the supplied information conforms to the request (e.g., do not provide a report in place of a forecast).

General Rule:

• Only transmit meteorological information supplied or agreed by the Meteorological Office, with the following exceptions:
  1. Indicated wind direction (degrees magnetic) and speed from control room anemometer indicators.
  2. RVR (Runway Visual Range) observations.
  3. Sudden or unexpected deteriorations needing immediate warnings for safety, with subsequent consultation with the Meteorological Office.
  4. Information from an aircraft in flight can be shared with other aircraft if useful, stating the source and time of observation. Severe icing or turbulence reports affecting safety must always be passed to affected aircraft and communicated to the duty meteorological forecaster.
  5. Cloud echoes observed on the situation display (Section 1, Chapter 6 covers the use of ATS surveillance systems for weather reporting and avoidance).
  6. Observations by ATS staff with a meteorological observer certificate.
  7. Observations at aerodromes without accredited observers are not official reports and must be prefixed with: “Unofficial observation from (name of aerodrome) at (time) UTC gives (observation)”.

Recording Observations:

• Record observations of visibility and RVR passed to aircraft when visibility is less than 1500 meters. These records must be available to the CAA on request.

Relaying SIGMET Messages:

• Relay SIGMET messages to affected aircraft with the least possible delay, without prejudicing the control of aircraft in flight.

Meteorological Information:

• Meteorological information supplied by a Meteorological Office is detailed in Section 7.

Question 22

What are the key aspects of ATIS messages as described in CAP 493?

Answer 22

• Purpose: Provides pilots with necessary information for approach, landing, or take-off decisions.
• Transmission: Sent on a published VHF frequency or selected VORs to reduce RTF loading; ideally under 30 seconds.
• Departure ATIS: Used only by ground aircraft due to limited range; combined ATIS can be used both on ground and in air.
• Coding: Messages are consecutively coded using the phonetic alphabet; changes are passed to pilots until acknowledged.
• Weather Changes: Indicate on RTF if rapid weather changes prevent inclusion in ATIS.
• Read-back: Departure ATIS requires read-back of altimeter settings unless included in start-up or taxi clearance.
• Acknowledgement: Departing pilots need not acknowledge unless requested; arriving pilots must acknowledge on initial contact with Approach Control.

Further Information: Detailed requirements and elements found in CAP 670 ATS Safety Requirements.

Question 23

What are the conditions and procedures for authorizing a visual approach in IFR flights according to CAP 493?

Answer 23

Conditions for Authorization:
* Pilot reports visual reference to the surface.
* Cloud ceiling is at or above the initial approach segment level, or
* Pilot reports visibility permits a visual approach and landing with reasonable assurance.

Minimum RVR:
* Visual approach not cleared if RVR is less than 800 m.
* If requested by the pilot with RVR < 800 m, inform the pilot of unavailability and request intentions.

Controlled Airspace:
* Standard separation maintained between IFR and Special VFR aircraft.

Outside Controlled Airspace:
* IFR flights may be authorized for visual approach under UK FIS.
* Deconfliction advice and traffic information depend on the service provided:
1. Procedural Service: No change in service level.
2. Deconfliction Service: Change to Traffic Service when descending below terrain safe level.
3. Traffic Service: Maintain surveillance identity, no service level change.
4. Basic Service: No service level change.

Wake Turbulence:
* Inform pilots of any recommended wake turbulence separation minima.

Caution for Unfamiliar Pilots:
* Exercise caution if flight crew may not be familiar with the aerodrome and terrain.

Question 24

What are the key procedures for instrument approaches according to CAP 493?

Answer 24

Notification and Pilot Familiarity:
* Official instrument approach procedures are notified by the CAA.
* Pilots are expected to be familiar with these procedures but can request information if needed.

Information Transmission:
* On initial contact:
1. Approach procedure details for category A aircraft.
2. Arrival level (if necessary).
3. Reversal manoeuvre details (outbound track, time/distance, level, procedure turn direction).
* On commencing final reversal:
1. Intermediate and final approach track.
2. Intermediate and final approach fixes with level instructions, stepdown fixes, and OCH.
3. Missed approach point and procedure (if required).

Straight-in Approaches:
* Items (1)(b) and (1)(c) can be omitted.

Pilot Copying Information:
* Procedure can be passed in one message if the pilot is copying it down.

Completion of Procedure:
* Pilots typically complete the procedure even if visual reference is established early.
* Pilots may request a visual approach to break-off the instrument procedure.
* Separation from other traffic is maintained unless the pilot cancels the IFR plan.

Question 25

What are the key holding procedures as described in CAP 493?

Answer 25

Procedure Compliance:
* Holding must follow notified procedures.
* ATC describes procedures if not known to the pilot.

Level Assignment:
* Aircraft are assigned levels to approach in correct order.
* First aircraft over the facility is at the lowest level, with subsequent aircraft at higher levels.

Departure Timing:
* Based on desired time interval between landings.
* Interval may be increased in poor weather for safe landing.

Alternative Procedures:
* Pilots may request alternative holding or communication procedures.
* Approval given if traffic conditions permit.

Question 26

What are the key aspects of establishing the approach sequence according to CAP 493?

Answer 26

Establishing Sequence:
* Facilitate maximum aircraft arrival with minimal delay.
* Priority given to certain aircraft as per Section 1.

Airborne Holding:
* If delay < EAT threshold, instruct pilots to hold at specific reporting point with delay estimate.

Expected Approach Times (EATs):
* Issued in advance to allow pilots to adjust flight paths.

Descending and Approaching:
* First aircraft descends from lowest holding level and starts approach when instructed.
* Second aircraft descends to vacated level after first reports vacating, or 1,000 ft below in severe turbulence.
* Second aircraft leaves holding when separation is established and normal landing assured.

Question 27

What are the key procedures for calculating and communicating Expected Approach Times (EATs) according to CAP 493?

Answer 27

Calculation of EATs:
* Approach Control calculates EATs for aircraft likely to be delayed before intermediate approach.

Communication of EATs:
* Controllers pass EATs to aircraft they are in contact with.
* EATs typically not issued for delays less than 20 minutes.
* Use “no delay expected” only if it accurately reflects the situation.
* Provide a general indication of delay if requested by the pilot, based on available information.

Question 28

What are the procedures for holding for weather improvement as per CAP 493?

Answer 28

Pilot Election to Hold:
* Pilots may choose to hold for weather improvement.
* Controllers provide routine weather reports and other relevant meteorological information.

First Aircraft in Holding Pattern:
* Advised with “no traffic delay expected.”
* No instruction to leave until pilot indicates intent to land.

Subsequent Aircraft:
* Advised with “delay not determined (number) aircraft holding for weather improvement.”
* Controllers should establish pilot intentions if not already stated.

Approach Intentions:
* Pilots wishing to approach are given routing instructions to descend clear of other traffic.
* Return to holding facility above other approaching aircraft.
* Provided with an expected approach time and placed in the normal landing sequence.

Missed Approaches:
* Consider the possibility of missed approaches in poor weather.
* Keep the lowest holding level vacant for such eventualities.

Question 29

What are the procedures for handling diversions as per CAP 493?

Answer 29

Liaison and Information Sharing:
* Controllers at aerodromes maintain close liaison with operating companies and the supervisor at the parent ACC.
* Pass pertinent information frequently to anticipate diversions and maintain smooth traffic flow.

Action During Diversions:
* Hold aircraft in the vicinity of the aerodrome.
* Inform ACC Watch Supervisor of the selected diversion aerodrome or seek advice if none is selected.
* Obtain and pass clearance instructions and other relevant instructions to aircraft.
* Pass diversion messages to aircraft.
* Provide alternate aerodrome weather reports if required.
* Advise the operating company or nominated addressee as per instructions in Section 1.

Question 30

What are the procedures for aerodromes receiving diversions according to CAP 493?

Answer 30

Informing Aerodrome Operator:
* Ensure full details of incoming diversions are passed to the Aerodrome Operator.

Post-Landing Actions:
* Send an arrival signal to:
1. Aerodrome of departure.
2. Point of first intended landing.
3. ACCs serving the original planned route.
4. LTCC Route charges section (EGTTYTYR).

Non-24-Hour Aerodromes:
* Maintain close liaison with Aerodrome Operator and parent ACC before closing watch if diversions are likely.
* Procedures for watch extensions agreed with Aerodrome Operator and published in MATS Part 2.

Question 31

What are the procedures for ATC clearances for departing aircraft according to CAP 493?

Answer 31

Clearance Specifications:
* Turn after take-off.
* Track before turning to desired heading.
* Initial level to fly.
* Time, point, and/or rate for level changes.

Clearance Expiry:
* Must not be later than the time issued by Area Control.

Separation Responsibility:
* Approach Control ensures separation from inbound aircraft after release point.

Pre-Release Point:
* Outbound clearances must account for inbound traffic separation unless using fixed procedures or RSYD restriction.

RSYD Restriction:
* Approach Control accepts separation responsibility.
* Must have release message or full details of conflicting aircraft.
* Ensure separation before transferring outbound aircraft to Area Control.

Pilot Requirements:
* On first contact, pilots must state callsign, SID designator (if applicable), current/passing level, and cleared level.
* Confirm correct initial level or clear to climb higher if needed.

Question 32

What should controllers do when an aircraft requests to enter controlled airspace but clearance cannot be issued immediately?

Answer 32

• Advise the pilot to remain outside controlled airspace.
• Inform the pilot when to expect clearance.
• Provide the pilot with a time check.