Clearance, Instruction and readback[PDF]
- 1 Introduction
- 2 Scope
- 3 Clearances and instructions
- 4 Rules
- 5 Read back requirements
- 6 See also
- 7 Reference
- 8 Author
Traffic includes aircraft in the air, aircraft on the manoeuvring area and vehicular traffic and other obstructions not permanently installed on the manoeuvring area.
ATC = Air traffic controller.
Clearances and instructions
- A clearance uses the term cleared
- An instruction will use an action verb in the imperative mood.
Examples of action verbs in the imperative mood: Taxi, stop, follow, descend, climb, turn, reduce, expedite, maintain…
There are other types of messages which are not clearances and instructions:
- ATC advises an expect-approach-clearance time, delay, traffic information
- ATC suggests any advice to an aircraft
- ATC requests any information from an aircraft.
When the controllers use the term “expect” in communication, this is never a clearance or instruction. It’s information (or advice). With the term “expect”, the pilot shall not proceed as if it were a clearance or instruction, but prepare his aircraft for this future instruction.
SAU2455, expect ILS approach runway 35.
Here, the pilot shall locate the ILS runway 35 approach chart and start his preparation for this approach. This communication shall not clear the pilot to the ILS approach runway 35. Pilot must hold at the last point of the previous clearance and not continue on the procedure given.
The clearances which allow a pilot to do something are:
- Landing clearance
- Take-off clearance
- Initial departure clearance
- Final approach clearance
- Oceanic clearance
Example ATC clearance:
DEHBA, cleared for take-off runway 01
DEHBA, cleared to land runway 33
DEHBA, cleared to Berlin, ATALO3N departure, FL110, Squawk 1000
DEHBA, cleared ILS approach runway 14R
Here are examples of instructions to be executed without delay by the pilot after receiving it:
- taxi instruction
- crossing runway
- backtracking runway
- climbing instruction
- descending instruction
- turning right or left to a heading instruction
- route instruction
Example ATC intructions:
DEHBA, taxi holding point runway 01DEHBA, route direct BEBIX
DEHBA, cross runway 25
DEHBA, maintain position taxi Alpha
DEHBA, line-up runway 17
DEHBA, backtrack runway 12
DEHBA, climb 3000ft
DEHBA, descent FL210
DEHBA, turn heading 240
- Aircraft identification.
- Clearance limit.
- Departure, en route, approach, or holding instructions.
- Special instructions or information.
- Traffic information.
At least 5 minutes before an aircraft reaches its clearance limit, the ATC shall issue:
- A further clearance;
- An approach clearance
- A holding clearance.
When the destination aerodrome is outside controlled airspace, the ATC unit responsible for the last controlled airspace shall issue the appropriate clearance for the flight to the limit of that controlled airspace.
Horizontal speed control instruction
Speed control shall not be applied to aircraft entering or establishing in a holding pattern Speed adjustment should be limited to those necessary to establish and/or maintain a desired separation minimum or spacing.
At levels at or above FL250 (7600m), speed adjustments should be expressed in multiples of 0.01 Mach. At levels below FL250 (7600m), speed adjustments should be expressed in multiples of 10kt (20km/h) based on the indicated airspeed.
Aircraft shall be advised when a speed control restriction is no longer required.
An arriving aircraft may be instructed to maintain its maximum speed, its minimum clean speed, its minimum speed or a specified speed.
Arriving aircraft should be permitted to operate in a clean configuration for as long as possible. Below 15000ft, FL150 or 4550m, speed reductions for a turboject aircraft shall not be less than 220Kt or 410 km/h IAS.
Only minor speed adjustments not exceeding ±20kt or ±40km/h IAS should be used for aircraft on intermediate and final approach.
Vertical speed control instruction
Vertical speed control may be applied between two climbing aircraft or two descending aircraft in order to establish or maintain a specific vertical separation minimum.
Vertical speed adjustments should be limited to those necessary to establish and/or maintain a desired separation minimum.
Aircraft shall be advised when a rate of climb or a rate of descent restriction is no longer required.
Route of flight
- the previously filed route has not been changed
- the aircraft will be radar-monitored until past the first compulsory reporting point.
You may instruct an aircraft to follow a specified track or heading for a specified time, to a location, or to an altitude, provided the instruction does not prevent the aircraft from clearing all obstructions and terrain in accordance with the specified minimum.
PROCEED VIA/REMAIN ON (specified radial or course) UNTIL (time or location).
CLIMB/DESCEND TO (altitude) ON (specified radial or course).
You should inform a high-performance aircraft if you anticipate that it may be required to hold en route or during descent.
An ATC unit can issue, with the holding clearance, an expected approach clearance time, expected further clearance time, or the time to depart the fix, and revise it as necessary.
EXPECT APPROACH CLEARANCE AT (time)
EXPECT FURTHER CLEARANCE AT (time)
DEPART (fix) AT (time).
Use the prefix “RNAV” in radio communications concerning RNAV(GPS) approaches.
Aircraft subject to ATC for part of flight
When an aircraft is uncontrolled in the airspace currently flown, and the aircraft will enter in airspace subject to ATC, the aircraft shall be advised to obtain its clearance from the ATC unit in which area the controlled flight will be commenced.
When an aircraft is subject to ATC in the airspace currently flown, and the aircraft will enter in an uncontrolled airspace, the aircraft shall normally be cleared to the point at which the controlled flight terminates.
Rules to know as a controller
- ATC units shall issue such ATC clearances and instructions as are necessary to prevent collisions and to expedite and maintain an orderly flow of air traffic.
- ATC units shall issue clearances and instructions that ensure an aircraft will remain within controlled airspace unless the aircraft requests otherwise.
- ATC units shall issue clearances and instructions with the least possible delay.
- ATC units shall identify and correct any error made during the transmission of a clearance or instruction.
- ATC units shall cancel and restate the clearance in full if there is any possibility of misunderstanding (readback).
You may issue a clearance amending a previous clearance:
Example: CDN92, CLEARED TO THE WINNIPEG AIRPORT VIA PRINCETON, J504 LUMSDEN, REMAINDER OF ROUTE UNCHANGED
When a flight plan specifies that the first portion of a flight will be subject to air traffic control and the subsequent portion will be uncontrolled, the aircraft shall normally be cleared to the point at which the controlled flight terminates.
Rules to know as a pilot
- If an air traffic control clearance is not suitable to the pilot-in-command of an aircraft, the flight crew may request and, if practicable, obtain an amended clearance.
- ATC clearance does not constitute authorisation to violate the applicable regulations for promoting the safety of flight operation or for any other purpose.
- When a flight will be partially uncontrolled, aircraft shall be advised to obtain its clearance from the ATC unit in which area the controlled flight will be commenced.
What can I do if, as a pilot-in-command, I do not receive any further clearance?
What can I do if, as a pilot-in-command, I cannot contact the air traffic controller?
Rule linked with TCAS resolution advisory (TA/RA)
Become aware that an aircraft has deviated from an ATC clearance or instruction as a result of an ACAS/TCAS or GPWS/TAWS resolution advisory manoeuvre.
Do not assume that other aircraft in the vicinity of an aircraft that is responding to an RA instruction are aware of its intended manoeuvres unless you are advised by them that they are also responding to an ACAS/ TCAS or GPWS/TAWS RA.
An ATC unit shall re-assume the responsibility for separation after an aircraft has responded to an ACAS/TCAS or GPWS/ TAWS RA when the aircraft informs you that:
- the manoeuvre is complete
- it has returned to its assigned altitude
- it is following an alternate clearance
Read back requirements
The following shall always be read back:
- ATC route clearances
- clearances and instructions to enter, land on, take off from, hold short of, cross and backtrack on any runway
- runway-in-use, altimeter settings, SSR codes, level instructions, heading and speed instructions
- transition level
- ICAO Documentation 4444 - Air Traffic Management - 16th Edition 2016 - Chapter 6.3
- ICAO Documentation Annex 11 - Air Traffic Services - 14th Edition - July 2016 - Chapter 3.7
- VID 150259 - Creation
- VID 150259 - Wiki integration
DATE OF SUBMISSION
- 00:12, 14 May 2021
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- The content of this documentation is intended for aviation simulation only and must not be used for real aviation operations.