Common Oceanic Procedures for Controllers
From IVAO North Atlantic Wiki
Revision as of 19:50, 12 December 2020 by Shaun.ellis
- 1 Airspace
- 2 Oceanic Control Procedures
- 3 Oceanic Radio Procedures
- 4 Datalink Oceanic Route Clearance Authorisation (ORCA)
- 5 Trackwise
All ATC is provided via position reporting only, as there is no radar available over the Atlantic. Furthermore all airspace between FL285 and FL420 is designated HLA airspace. Basically, this imposes far more rigorous navigation limitations on aircraft and imposes the use of pre-defined North Atlantic Tracks (NATs) as opposed to random tracks (here).
Because of the vast distances to be covered, the lack of navigational aids and the weather conditions over the North Atlantic, a system of daily tracks exists. North Atlantic Tracks: dynamic airways which change location and direction twice daily to facilitate traffic flow across the North Atlantic. In the real world you will find most flights from America to Europe (Eastbound) will take place during the night, whilst Europe to America (westbound) tends to occur during the day. On IVAO, flights in both directions are permitted at all times and the semi-circular rule is applied.
All pilots are urged to consult the current tracks to plan their route across the Atlantic. The current NATs are available here.
NATs are only within HLA airspace. Aircraft flying above or below this airspace must file a random route.
The hours of validity of the two Organized Track Systems (OTS) are normally:
day-time OTS (westbound): 1130z – 1900z night-time OTS (eastbound): 0100z – 0800z The hours of validity are specified in the track message.
The most northerly track of a day OTS is designated as NAT Alpha; the adjacent track to the south as NAT Bravo; etc. For the night OTS, the most southerly track is designated as NAT Zulu; the adjacent track to the north as NAT Yankee; etc. Flight levels are allocated for use within the OTS and in most cases, details of domestic entry and exit routings associated with individual tracks are provided in the NAT Message.
Random Track System
Random tracks are basically handmade routes across the North Atlantic, using Lat/Lon waypoints, just like the NATs. Random tracks are used for routes where the NATs are not suitable. However random tracks which cross through, or come within 120 miles of the NATs, will not be accepted. Aircraft flying these routes are expected to file a NAT.
Examples: For a westbound flight during the night you have to file a random routing For a eastbound flight during the day you have to file a random routing For flights above F400 (eastbound) and/or F390 (westbound) you have to file a random routing
Before attempting to connect to any oceanic position all controllers, regardless of division of origin, must complete oceanic training which is offered by the oceanic team.
Oceanic Control Procedures
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.
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.
Note: A time limitation is only given if the aircraft's ETA at the NAT needs to be altered. In the below 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.
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.
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.
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.
Minimum longitudinal separation for aircraft on the same track is ten (10) minutes flying time.
Aircraft on crossing tracks at the same level must be fifteen (15) minutes apart at the point where their tracks cross.
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.
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.
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.
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.
Communication with Aircraft
Communication with aircraft over the North Atlantic shall be made by relay through the FSS stations.
Oceanic Radio Procedures
Description of Position
The FSS position is responsible for relaying communications between the OCC and aircraft over the North Atlantic, as well as entering position updates into the OCMS. Up to three flight service specialists may work as Gander FSS. The area of coverage for each sector will depend on actual traffic, and shall be decided by the FSS supervisor , S sector (or the EGGX-Staff) Typically N serves traffic north of 50W, S serves traffic south of 50W and W traffc west from 50W onwards.
All communications take place HF frequencies. As the current pilot/controller software doesn’t support HF frequencies a modified decimal system has been arranged where the frequency 12237 kHz is entered as 122.37 in IvAc. Phaseology for the said frequency remains “one two two three seven kilohertz”
SELCAL shall be used whenever aircraft are equipped. On initial call-up SELCAL should be verified. Subsequent communications shall always be initiated with a SELCAL signal. To transmit a SELCAL signal enter .selcal [callsign] in the IvAc comm. box and transmit. If the SELCAL check fails the aircraft should be advised to monitor the frequency continuously.
Aircraft will transmit position reports to Gander or/and Shanwick FSS at each waypoint along their route, or every 45 minutes, whichever is shorter. Upon receiving the report Gander FSS or/and Shanwick FSS shall enter the estimate time as well as any remarks/requests into the OCMS flight strip.
If any portion of the aircraft’s transmission is unreadable, or if parts are omitted reconfirm with the aircraft before reading back the position report.
Position Report Phraseology
Relay of Requests
Aircraft will make all requests on FSS frequencies. These shall be relayed to the OCC controller:
Datalink Oceanic Route Clearance Authorisation (ORCA)
Aircraft Communication Addressing and Reporting System (ACARS) equipped arcraft may request and receive their Oceanic clearance via datalink, utilising the Oceanic Route Clearance Authorisation system (ORCA). This system should not be used by aircraft within 30 minutes of entry to Oceanic airspace; RTF should then be used.
Aircraft will request clearance using the web-based FMC, following the included instructions. When a clearance request is made a flight-strip will appear in the Pending bay on the ORCA ATC page. The flight should be checked for conflict with the aircraft in the relevant FL/Track section on the Cleared bay. If required, the FL, ETA or track can be changed before clearing the aircraft. Alternatively, ATC can request negotiation with the flight by pressing the DENY button. The pilot will then receive a message requesting radio contact.
Aircraft in the Cleared bay can have their details changed by clicking on the callsign.
If you are interested in the real procedures and workflow the video below might be what you are looking for: