Control Of Traffic - S1 - C4

Question 1

What are the contents of a clearance? (5)

Answer 1

• Aircraft identification as shown in the flight plan;
• Clearance limit;
• Route, where prescribed in MATS Part 2;
• Levels 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 approach or departure manoeuvres, communications and the time of expiry of the clearance.

Note: The time of expiry of the clearance indicates the time after which the clearance will be automatically cancelled if the flight has not been commenced.

Question 2

What is a clearance limit?

Answer 2

A clearance limit is the point to which an aircraft is granted an ATC clearance and shall be specified by naming:
- an aerodrome;
- a reporting point; or
- a controlled or advisory airspace boundary.
An aircraft shall be cleared for the entire route to the aerodrome of first intended landing when:
- it has planned to remain within controlled or advisory airspace throughout the flight; and
- there is reasonable assurance that prior co ordination 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.
If the clearance for the levels covers only part of the route, it is important to specify that part to enable the pilot to comply with the radio failure procedures.

Question 3

What is an amendment to a clearance?

Answer 3

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.
Similar care must be exercised when a controller issues a clearance, which amends the vertical profile of an aircraft on a SID. For example, “climb now FL120” automatically cancels the vertical profile of the SID. If the profile contains a restriction that provides vertical separation from conflicting traffic on another SID, the restriction must be reiterated, e.g. “climb now FL120 cross XYZ 5,000 feet or above”, unless separation is ensured by other means.
Similarly, when controllers issue instructions which amend the SID route, they are to confirm the level profile to be followed, e.g. “fly heading 095, climb now FL80” or “route direct EFG, stop climb at altitude 5,000 feet”.

Question 4

What is flight priorities?

Answer 4

Normally requests for clearances shall be dealt with in the order in which they are received and issued according to the traffic situation.
However, certain flights are given priority over others and the following table shows the categorisation.
When two or more flights of different categories request clearance the flight with the highest category shall be dealt with first.

Question 5

Flight priorities
Minimum Fuel & Fuel Shortage

Answer 5

A pilot’s declaration of “MINIMUM FUEL” indicates that no further fuel diversion options are available where the aircraft is committed to land at the pilot’s nominated aerodrome of landing with not less than ‘final reserve fuel’.

Note: Final reserve fuel is typically fuel for 30 minutes of flight for turbine powered aircraft or 45 minutes for piston powered aircraft. (ICAO)

Question 6

Flight priority
A

Answer 6

A

Aircraft in emergency (e.g. engine fault, fuel shortage, seriously ill passenger).
Aircraft which have declared a ‘Police Emergency’.
Ambulance/Medical/Search and Rescue aircraft when the safety of life is involved. (See note).

Question 7

Flight Priorty
B

Answer 7

B
Flights operating for Search and Rescue or other humanitarian reasons.
Police flights under normal operational priority.
Other flights authorised by the CAA, including Open Skies Flights.

Question 8

Flight Priorty
C

Answer 8

Royal Flights
Flights carrying visiting Heads of State

Question 9

Flight Priorty
D

Answer 9

Flights carrying the:
- Prime Minister,
- Chancellor of the Exchequer,
- Home Secretary, or
- Secretary of State for Foreign, Commonwealth and Development Affairs.

Flights carrying visiting Heads of Government notified by the CAA.

Question 10

Flight Priorty
E

Answer 10

HEMS/Search and Rescue positioning flights.
Other flights authorised by the CAA, including flight check aircraft engaged on, or in transit to, time or weather critical calibration flights.

Question 11

Flight Priority
NORMAL FLIGHTS

Answer 11

• 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”)

Question 12

Flight Priorty
Z

Answer 12

• Training, non-standard and other flights.

Question 13

Transfer of control

Answer 13

Transfer of control is achieved when a flight, which is operating in accordance with the co-ordination, has reached the position or level agreed between the transferring and accepting units.

Question 14

Transfer of communication

Answer 14

Transfer of control must not be confused with transfer of communication.
Transfer of communication may be permitted so that instructions, which become effective later,
can be issued. It is emphasised that an accepting ATC unit which is in communication with an aircraft not having yet reached the stage of transfer of control shall not alter the clearance without the approval of the transferring unit.

Question 15

Where does transfer of control take place?

Answer 15

Transfer of control normally takes place:
- At an agreed reporting point;
- On an estimate for an FIR boundary;
- At or passing an agreed level; or
- While the aircraft is climbing or descending to a previously agreed level, provided that the transferring controller has ensured that standard separation will exist between the transferred aircraft and all others for the remainder of the climb or descent.