Oceanic Control (OCC) procedures

3.1 Description of position

The OCC position is responsible for maintaining required separation within the Oceanic Control area by using the position reports relayed by FSS. OCC shall also approve/deny all requests for altitude and/or speed changes as relayed by FSS.
IvAc shall only be used to communicate via text to other pilots and controllers.

The OCC shall process and approve all oceanic clearances. ORCA may be used in lieu of voice. ORCA procedures are located in section 7.

There are two (2) Oceanic Control Centres. One located in Gander and one Located in Prestwick. See sections 5 and 6 respectively for unit-specific procedures.

3.2 Oceanic Clearance

Flights planned through Oceanic airspace must obtain a separate Oceanic Clearance. The request is made between 30 and 90 minutes prior to the ETA of the Oceanic Entry point (via Voice or Datalink). It is the responsibility of the Oceanic Controller to ensure that all aircraft enter oceanic airspace properly spaced and remain spaced throughout the crossing.


  • Pilot: "Good evening Gander Center, Speedbird 188”
  • ATC: "Speedbird 188, Gander Center, Good evening pass your message"
  • Pilot: "Speedbird 188 requesting clearance to London Heathrow via track WHISKEY, Flight Level 380, Mach .83. Estimating COLOR at 0246 zulu. TMI068"
  • ATC: "Speedbird 188 cleared to London Heathrow, Track WHISKEY, FL380, Mach .83, cross VIXUN latest at 0248 zulu"
  • Pilot: "Speedbird 188 cleared to London Heathrow, Track WHISKEY, FL380, Mach .83, crossing VIXUN latest at 0248 zulu,"
  • ATC: "Speedbird 188, your readback is correct, return to previous frequency."

Note: A time limitation is only given if the aircraft's ETA at the NAT needs to be altered. In the above example BAW188 was cleared via the requested route. If this isn't the case the route would be modified. (It's a good idea to let the pilot know if this is the case before issuing the clearance so you won't have to repeat it because the pilot wasn't properly prepared)

Before issuing clearance the controller shall insert the flight into ORCA and confirm positive spacing exists and will be maintained throughout the crossing. It is the OCC controller’s responsibility to co-ordinate routing and/or altitude changes with domestic units.

Actual clearance to change course and/or altitude will always be given by the domestic unit. It is not necessary to pass entry times as the domestic units have a dedicated monitor.

3.3 Minimum separation

3.3.1 Vertical

Minimum vertical separation within HLA airspace is 1,000 feet up to and including FL410, and 2,000 feet above that.
Supersonic flights require 4,000 feet vertical separation from all other traffic if no other form of separation exists. This applies at any level for aircraft at supersonic speeds.

3.3.2 Lateral

Minimum lateral separation is sixty (60) Nautical Miles.
Parallel tracks which are spaced apart by one (1) degree, and which change latitude by no more than two (2) degrees over a longitude of ten (10) degrees are deemed to be separated.

Example: tracks from 50N020W to 52N030W and 49N020W to 51N030W are separated. 52N010W to 55N020W and 51N010W to 54N020W are not separated.

NATs are normally defined so that they do not change latitude by more than 2 degrees for each 10 degrees longitude difference thereby ensuring separation.

3.3.3. Longitudinal

Minimum longitudinal separation for aircraft on the same track is ten (10) minutes flying time.

Example: An aircraft passing 49N040W at FL380 must not be followed by another at the same level on the same track until ten minutes have elapsed after the first one passed that point.

Aircraft on crossing tracks at the same level must be fifteen (15) minutes apart at the point where their tracks cross.

3.3.4 Speed differences

Aircraft with different speeds on the same track/FL will gradually get closer or further apart. It is imperative to monitor this change of spacing closely for loss of separation. Aircrafts are requested to maintain the cleared speed given with the oceanic clearance.

When calculating initial spacing use the following formula: Slow followed by fast: Add one (1) minute to the standard for every increase of 0.01 Mach number of the second aircraft.

Example: M0.80 followed by M0.84 requires FOURTEEN minutes at ocean entry same track same level.

Fast followed by slow. Subtract one (1) minute from the standard for every decrease of 0.02 Mach number of the second aircraft. The minimum is 5 minutes at Oceanic entry.

Example: M0.84 followed by M0.80 requires a minimum of EIGHT minutes separation at ocean entry same track same level.

If two aircraft at different speeds are entering Oceanic Airspace at the same point but following tracks which will be separated by no less than sixty (60) nautical miles, or ten (10) degrees of longitude after entry the increase above is not required. The reduction above may still be applied.
If this situation occurs inside Oceanic Airspace (as opposed to at entry) then they are considered to be on crossing tracks and the fifteen (15) minute rule applies. There is no reduction to the fifteen minute rule for fast followed by slow on crossing tracks.

3.3.5 Opposite direction

The following is included in order to determine the separation requirement for aircraft wishing to climb/descend through the level of another aircraft opposite direction, whether on the same track or crossing tracks opposite direction.

Vertical separation must be established by a position calculated to be thirty (30) minutes flying time before the position/time at which it is estimated that they will pass one another, and must continue to exist until 30 minutes after they are estimated to have passed. If it can be positively established that they have passed, by both having reported passing the same Oceanic Reporting Point then the separation may be reduced to 10 minutes after they are known to have passed each other.

Example: Two aircrafts,
            A: routing 55N010W 56N020W 57N030W
            estimates 56N020W at 1234Z and 57N030W at 1304Z
            B: routing 56N030W 56N020W 56N010W.
            estimates 56N030W at 1224Z and 56N020W at 1254Z.

Inspection and calculation indicates that they will both be approximately one third of the way from 20W to 30W (or two thirds of the way from 30W to 20W) at approximately the same time (1244Z). So vertical separation must exist from 1214Z until 1314Z. Once (B) has reported coordinate 20W the pass will have been established and one or other may climb/descend through the other aircraft's level after 1304 (ten minutes after they are known to have passed).

3.4 Communication with aircraft

Communication with aircraft over the North Atlantic shall be made by relay through the FSS stations. See sections 5 and 6 for Gander and Shanwick intercom procedures.