3.2.4 Air traffic control clearances
3.2.4.1 Air traffic control clearances shall be based solely on the following requirements for providing air traffic control service:
- Clearances shall be issued solely for expediting and separating air traffic and be based on known traffic conditions which affect safety in aircraft operation. Such traffic conditions include not only aircraft in the air and on the manoeuvring area over which control is being exercised, but also any vehicular traffic or other obstructions not permanently installed on the manoeuvring area in use.
- ATC units shall issue such ATC clearances as necessary to prevent collisions and to expedite and maintain an orderly flow of air traffic.
- ATC clearances shall be issued early enough to ensure that they are transmitted to the aircraft in sufficient time for it to comply with them.
3.2.4.2 Operation subject to clearance
3.2.4.2.1 An air traffic control clearance shall be obtained prior to operating a controlled flight, or a portion of a flight as a controlled flight. Such clearance shall be requested through the submission of a flight plan to an air traffic control unit.
3.2.4.2.2 The pilot-in-command of an aircraft shall inform ATC if an air traffic control clearance is not satisfactory. In such cases, ATC will issue an amended clearance, if practicable.
3.2.4.2.3 Whenever an aircraft has requested a clearance involving priority, a report explaining the necessity for such priority shall be submitted, if requested by the appropriate air traffic control unit.
3.2.4.2.4 Potential reclearance in flight. If, prior to departure, it is anticipated that, depending on fuel endurance and subject to reclearance in flight, a decision may be taken to proceed to a revised destination aerodrome, the appropriate air traffic control units shall be so notified by the insertion in the flight plan of information concerning the revised route (where known) and the revised destination.
3.2.4.2.5 An aircraft operated on a controlled aerodrome shall not taxi on the manoeuvring area without clearance from the aerodrome control tower and shall comply with any instructions given by that unit.
3.2.4.2.6 When vectoring or assigning a direct routing not included in the flight plan, which takes an IFR flight off published ATS route or instrument procedure, an air traffic controller providing ATS surveillance service shall issue clearances such that the prescribed obstacle clearance exists at all times until the aircraft reaches the point where the pilot re-joins the flight plan route or joins a published ATS route or instrument procedure.
3.2.4.3 Clearances for transonic flight
3.2.4.3.1 The air traffic control clearance relating to the transonic acceleration phase of a supersonic flight shall extend at least to the end of that phase.
3.2.4.3.2 The air traffic control clearance relating to the deceleration and descent of an aircraft from supersonic cruise to subsonic flight shall seek to provide for uninterrupted descent at least during the transonic phase.
3.2.4.4 Contents of clearances
3.2.4.4.1 An air traffic control clearance shall indicate:
- aircraft identification as shown in the flight plan;
- clearance limit;
- route of flight, …
- the route of flight shall be detailed in each clearance when deemed necessary; and
- the phrase ‘cleared via flight planned route’ shall not be used when granting a re-clearance;
- level(s) of flight for the entire route or part thereof and changes of levels if required;
- any necessary instructions or information on other matters such as ATFM departure slot if applicable, approach or departure manoeuvres, communications and the time of expiry of the clearance.
3.2.4.5 Read-back of clearances, instructions and safety-related information
3.2.4.5.1 The flight crew shall read back to the air traffic controller safety-related parts of ATC clearances and instructions which are transmitted by voice. The following items shall always be read back:
- ATC route clearances;
- clearances and instructions to enter, land on, take off from, hold short of, cross, taxi and backtrack on any runway; and
- runway-in-use, altimeter settings, SSR codes, newly assigned communication channels, level instructions, heading and speed instructions; and
- transition levels, whether issued by the controller or contained in ATIS broadcasts.
3.2.4.5.2 Other clearances or instructions, including conditional clearances and taxi instructions, shall be read back or acknowledged in a manner to clearly indicate that they have been understood and will be complied with.
3.2.4.5.3 The controller shall listen to the read-back to ascertain that the clearance or instruction has been correctly acknowledged by the flight crew and shall take immediate action to correct any discrepancies revealed by the read-back.
3.2.4.6 Changes in clearance regarding route or level
3.2.4.6.1 When issuing a clearance covering a requested change in route or level, the exact nature of the change shall be included in the clearance.
3.2.4.6.2 When traffic conditions will not permit clearance of a requested change, the word ‘UNABLE’ shall be used. When warranted by circumstances, an alternative route or level shall be offered.
3.2.4.7 Clearance related to altimetry
3.2.4.7.1 For flights in areas where a transition altitude is established, the vertical position of the aircraft shall, except as provided for in 3.2.4.7.5 below, be expressed in terms of altitudes at or below the transition altitude and in terms of flight levels at or above the transition level. While passing through the transition layer, the vertical position shall be expressed in terms of flight levels when climbing and in terms of altitudes when descending.
3.2.4.7.2 The flight crew shall be provided with the transition level in due time prior to reaching it during descent.
3.2.4.7.3 Except when it is known that the aircraft has already received the information in a directed transmission, an QNH altimeter setting shall be included in:
- the descent clearance, when first cleared to an altitude below the transition level;
- the approach clearance or the clearance to enter the traffic circuit;
- the taxi clearance for departing aircraft.
3.2.4.7.4 A QFE altimeter setting shall be provided to aircraft on request or on a regular basis in accordance with local arrangements.
3.2.4.7.5 When an aircraft has been given clearance to land or where an aircraft has been informed that the runway is available for landing at AFIS aerodromes and that aircraft is completing its approach using atmospheric pressure at aerodrome elevation (QFE), the vertical position of that aircraft shall be expressed in terms of height above aerodrome elevation during that portion of its flight for which QFE may be used, except that it shall be expressed in terms of height above runway threshold elevation:
- for instrument runways if the threshold is 2 m (7 ft) or more below the aerodrome elevation; and
- for precision approach runways.
3.2.4.8 Conditional clearances
3.2.4.8.1 Conditional phrases, such as ‘behind landing aircraft’ or ‘after departing aircraft’, shall not be used for movements affecting the active runway(s), except when the aircraft or vehicles concerned are seen by the appropriate controller and pilot. The aircraft or vehicle causing the condition in the clearance issued shall be the first aircraft/vehicle to pass in front of the other aircraft concerned. In all cases, a conditional clearance shall be given in the following order and consist of:
- the call sign;
- the condition;
- the clearance; and
- a brief reiteration of the condition.
3.2.4.9 Coordination of clearances
3.2.4.9.1 An air traffic control clearance shall be coordinated between air traffic control units to cover the entire route of an aircraft or a specified portion thereof as described in provisions 3.2.4.9.2 to 3.2.4.9.6.
3.2.4.9.2 An aircraft shall be cleared for the entire route to the aerodrome of first intended landing:
- when it has been possible, prior to departure, to coordinate the clearance between all the units under whose control the aircraft will come; or
- when there is reasonable assurance that prior coordination will be effected between those units under whose control the aircraft will subsequently come.
3.2.4.9.3 When coordination as in 3.2.4.9.2 has not been achieved or is not anticipated, the aircraft shall be cleared only to that point where coordination is reasonably assured; prior to reaching such point, or at such point, the aircraft shall receive further clearance, holding instructions being issued as appropriate.
3.2.4.9.4 When prescribed by the ATS unit, aircraft shall contact a downstream air traffic control unit, for the purpose of receiving a downstream clearance prior to the transfer of control point.
- Aircraft shall maintain the necessary two-way communication with the current air traffic control unit whilst obtaining a downstream clearance.
- A clearance issued as a downstream clearance shall be clearly identifiable as such to the pilot.
- Unless coordinated, downstream clearances shall not affect the aircraft’s original flight profile in any airspace, other than that of the air traffic control unit responsible for the delivery of the downstream clearance.
3.2.4.9.5 When an aircraft intends to depart from an aerodrome within a control area to enter another control area within a period of thirty minutes, or such other specific period of time as has been agreed between the area control centres concerned, coordination with the subsequent area control centre shall be effected prior to issuance of the departure clearance.
3.2.4.9.6 When an aircraft intends to leave a control area for flight outside controlled airspace, and will subsequently re-enter the same or another control area, a clearance from the point of departure to the aerodrome of first intended landing may be issued. Such clearance or revisions thereto shall apply only to those portions of the flight conducted within controlled airspace.
3.2.5 Adherence to flight plan
3.2.5.1 Except as provided for in 3.2.5.2 and 3.2.5.4 an aircraft shall adhere to the current flight plan or the applicable portion of a current flight plan submitted for a controlled flight unless a request for a change has been made and clearance obtained from the appropriate air traffic control unit, or unless an emergency situation arises which necessitates immediate action by the aircraft, in which event as soon as circumstances permit, after such emergency authority is exercised, the appropriate air traffic services unit shall be notified of the action taken and that this action has been taken under emergency authority.
3.2.5.1.1 Unless otherwise authorised by the competent authority, or directed by the appropriate air traffic control unit, controlled flights shall, in so far as practicable:
- when on an established ATS route, operate along the defined centre line of that route; or
- when on any other route, operate directly between the navigation facilities and/or points defining that route;
- when in FRALB airspace, operate directly between the FRA entry point via the intermediate points to the FRA exit point.
3.2.5.1.2 Unless otherwise authorised by the competent authority, or directed by the appropriate air traffic control unit, an aircraft operating along an ATS route segment defined by reference to very high frequency omnidirectional radio ranges shall change over for its primary navigation guidance from the facility behind the aircraft to that ahead of it at, or as close as operationally feasible to, the changeover point, where established.
3.2.5.1.3 Deviation from the requirements in point 3.2.5.1.1 shall be notified to the appropriate ATS unit.
3.2.5.2 Inadvertent changes. In the event that a controlled flight inadvertently deviates from its current flight plan, the following action shall be taken:
- Deviation from track: if the aircraft is off track, action shall be taken forthwith to adjust the heading of the aircraft to regain track as soon as practicable.
- Variation in true airspeed: if the average true airspeed at cruising level between reporting points varies or is expected to vary by plus or minus 5 per cent of the true airspeed, from that given in the flight plan, the appropriate air traffic services unit shall be so informed.
- Deviation from Mach number/true airspeed: if the sustained Mach number/true airspeed at cruising level varies by plus or minus Mach 0.02 or more, or plus or minus 19km/h (10kt) true airspeed or more from the current flight plan, the appropriate air traffic services unit shall be so informed.
- Change in time estimate: if the time estimate for the next applicable reporting point, flight information region boundary or destination aerodrome, whichever comes first, is found to be in error in excess of 2 minutes from that notified to ATS or such other period of time as prescribed by the competent authority, a revised estimated time shall be notified as soon as possible to the appropriate ATS unit.
3.2.5.3 Intended changes. Requests for flight plan changes shall include information as indicated hereunder:
3.2.5.3.1 Change of cruising level: aircraft identification; requested new cruising level and cruising speed at this level, revised time estimates (when applicable) at subsequent flight information region boundaries.
3.2.5.3.2 Change of route:
- Destination unchanged: aircraft identification; flight rules; description of new route of flight including related flight plan data beginning with the position from which requested change of route is to commence; revised time estimates; any other pertinent information.
- Destination changed: aircraft identification; flight rules; description of revised route of flight to revised destination aerodrome including related flight plan data, beginning with the position from which requested change of route is to commence; revised time estimates; alternate aerodrome(s); any other pertinent information.
3.2.5.4 Weather deterioration below the VMC. When it becomes evident that flight in VMC in accordance with its current flight plan will not be practicable, a VFR flight operated as a controlled flight shall:
- request an amended clearance enabling the aircraft to continue in VMC to destination or to an alternative aerodrome, or to leave the airspace within which an ATC clearance is required; or
- if no clearance in accordance with a) can be obtained, continue to operate in VMC and notify the appropriate ATC unit of the action being taken either to leave the airspace concerned or to land at the nearest suitable aerodrome; or
- if operated within a control zone, request authorisation to operate as a special VFR flight; or
- request clearance to operate in accordance with the instrument flight rules.
3.2.6 Position reports3.2.6.1 Unless exempted by the competent authority or by the appropriate air traffic services unit under conditions specified by that authority, a controlled flight shall report to the appropriate air traffic services unit, as soon as possible, the time and level of passing each designated compulsory reporting point, together with any other required information. Position reports shall similarly be made in relation to additional points when requested by the appropriate air traffic services unit. In the absence of designated reporting points, position reports shall be made at intervals prescribed by the competent authority or specified by the appropriate air traffic services unit.
3.2.6.1.1 When a controlled flight has been exempted from the requirement to report at compulsory reporting points, pilots shall, unless automated position reporting is in effect, resume voice position reporting:
- when so instructed;
- when advised that the ATS surveillance service has been terminated; or
- when advised that the ATS surveillance identification is lost.
3.2.6.1.2 The format of position reports shall be in accordance with Point A, Appendix 5 of SERA.
3.2.7 Termination of control3.2.7.1 A controlled flight shall, except when landing at a controlled aerodrome, advise the appropriate ATC unit as soon as it ceases to be subject to air traffic control service.
3.2.8 Communications3.2.8.1 An aircraft operated as a controlled flight shall maintain continuous air-ground voice communication watch on the appropriate communication channel of, and establish two-way communication as necessary with, the appropriate air traffic control unit, except as may be prescribed by the relevant ANSP in respect of aircraft forming part of aerodrome traffic at a controlled aerodrome.
3.2.8.2 Communication failure. If a communication failure precludes compliance with 3.2.8.1, the aircraft shall comply with the voice communication failure procedures of Annex 10, Volume II, and with such of the following procedures as are appropriate. The aircraft shall attempt to establish communications with the appropriate air traffic control unit using all other available means. In addition, the aircraft, when forming part of the aerodrome traffic at a controlled aerodrome, shall keep a watch for such instructions as may be issued by visual signals.
3.2.8.2.1 If in visual meteorological conditions, the aircraft shall:
- continue to fly in visual meteorological conditions; land at the nearest suitable aerodrome; and report its arrival by the most expeditious means to the appropriate air traffic services unit;
- if considered advisable, complete an IFR flight in accordance with 3.2.8.2.2.
3.2.8.2.2 If in instrument meteorological conditions or when the pilot of an IFR flight considers it inadvisable to complete the flight in accordance with 3.2.8.2.1 a), the aircraft shall:
- unless otherwise prescribed on the basis of regional air navigation agreement, in airspace where radar is not used in the provision of air traffic control, maintain the last assigned speed and level, or minimum flight altitude if higher, for a period of 20 minutes following the aircraft’s failure to report its position over a compulsory reporting point and thereafter adjust level and speed in accordance with the filed flight plan;
- in airspace where radar is used in the provision of air traffic control, maintain the last assigned speed and level, or minimum flight altitude if higher, for a period of 7 minutes following:
- the time the last assigned level or minimum flight altitude is reached; or
- the time the transponder is set to Code 7600; or
- the aircraft’s failure to report its position over a compulsory reporting point;
whichever is later, and thereafter adjust level and speed in accordance with the filed flight plan;
- when being radar vectored or having been directed by ATC to proceed offset using area navigation (RNAV) without a specified limit, rejoin the current flight plan route no later than the next significant point, taking into consideration the applicable minimum flight altitude;
- proceed according to the current flight plan route to the appropriate designated navigation aid or fix serving the destination aerodrome and, when required to ensure compliance with e) below, hold over this aid or fix until commencement of descent;
- commence descent from the navigation aid or fix specified in d) at, or as close as possible to, the expected approach time last received and acknowledged; or, if no expected approach time has been received and acknowledged, at, or as close as possible to, the estimated time of arrival resulting from the current flight plan;
- complete a normal instrument approach procedure as specified for the designated navigation aid or fix; and
- land, if possible, within 30 minutes after the estimated time of arrival specified in e) or the last acknowledged expected approach time, whichever is later.
Note: The provision of air traffic control service to other flights operating in the airspace concerned will be based on the premise that an aircraft experiencing communication failure will comply with the rules in 3.2.8.2.2.