8-10-3. LONGITUDINAL SEPARATION
In accordance with Chapter 8, Offshore/Oceanic Procedures, Section 3, Longitudinal Separation, apply the following:
- Minima based on time:
- 15 minutes between turbojet aircraft.
- The prescribed minima in accordance with Paragraph 8-3-3, Mach Number Technique.
- 20 minutes between other aircraft.
- Clear an aircraft for an ADS-B In Trail Procedure (ITP) climb or descent provided the following conditions are satisfied:
- The ITP climb or descent has been requested by the pilot;
- The aircraft identification of each reference aircraft in the ITP request exactly matches the Item 7 - aircraft identification of the corresponding aircraft’s filed flight plan;
- The reported ITP distance between the ITP aircraft and any reference aircraft is 15 NM or more;
- Both the ITP aircraft and reference aircraft are either on:
- (a) same identical tracks and any turn at a waypoint shall be limited to less than 45 degrees; or
- (b) same tracks with no turns permitted that reduce required separation during the ITP.
NOTE: Same identical tracks are where the angular difference is zero degrees.
- No speed or route change clearance shall be issued to the ITP aircraft until the ITP climb or descent is completed;
- The altitude difference between the ITP aircraft and any reference aircraft shall be 2000 ft or less;
- No instruction to amend speed, altitude or route shall be issued to any reference aircraft until the ITP climb or descent is completed;
- The maximum closing speed between the ITP aircraft and each reference aircraft shall be Mach 0.06; and
- The ITP aircraft shall not be a reference aircraft in another ITP clearance.
NOTE: ATOP is designed to check for the above criteria prior to allowing the minima to be provided.
- Minima based on distance using Automatic Dependent Surveillance - Contract (ADS-C) in the Anchorage Oceanic and Anchorage Continental CTAs only:
NOTE: The minima described in this paragraph are not applicable within airspace in the Anchorage Arctic CTA.
- Apply the minima as specified in TBL 8-10-1 between aircraft on the same track within airspace in the Anchorage Oceanic and Anchorage Continental CTAs designated for Required Navigation Performance (RNP), provided:
- (a) Direct controller/pilot communication via voice or Controller Pilot Data Link Communications (CPDLC) is established, and
- (b) The required ADS-C periodic reports are maintained and monitored by an automated flight data processor (for example, ATOP).
TBL 8-10-1 ADS-C Criteria
||Maximum ADS-C Periodic Reporting Interval
- Aircraft on reciprocal tracks in the Anchorage Oceanic and Anchorage Continental CTAs may be cleared to climb or descend to or through the altitude(s) occupied by another aircraft provided:
- (a) An ADS-C position report on at least one of the aircraft has been received beyond the passing point, and
- (b) The aircraft have passed each other by the applicable separation minimum.
NOTE: ATOP has been designed to check for the above criteria prior to allowing the minima to be provided.
- When an ADS-C periodic or waypoint change event report is overdue by 3 minutes, the controller must take action to obtain an ADS-C report.
- If no report is received within 6 minutes of the time the original report was due, the controller must take action to apply another form of separation.
- Aircraft on the same track may be cleared to climb or descend through the level of another aircraft provided:
- (a) The longitudinal distance between the aircraft is determined from near simultaneous ADS C demand reports and the ATOP software is used to ensure the following conditions are met;
- (b) The longitudinal distance between the aircraft, as determined in (a) above, is not less than:
- (1) 15 NM when the preceding aircraft is at the same speed or faster than the following aircraft; or
- (2) 25 NM when the following aircraft is not more than Mach 0.02 faster than the preceding aircraft.
- (c) The altitude difference between aircraft is not more than 2000 ft;
- (d) The clearance is for a climb or descent of 4000 ft or less;
- (e) Both aircraft are filed as single flights not flying in formation with other aircraft;
- (f) Both aircraft are in level flight at a single altitude;
- (g) Both aircraft are same direction;
- (h) Neither aircraft are on a weather deviation;
- (i) Neither aircraft have an open CPDLC request for a weather deviation;
- (j) Neither aircraft are on an offset with a rejoin clearance; and
- (k) The clearance is issued with a restriction that ensures vertical separation is re-established within 15 minutes from the first demand report request.
- Minima based on DME/RNAV:
Apply the following DME/RNAV minima in Control 1234H, Control 1487H, and the Norton Sound High Control areas to turbojet aircraft established on or transitioning to the North Pacific (NOPAC) Route System.
- 30 NM between aircraft when DME reports or radar observations are used to establish the distance, otherwise at least 40 NM based on RNAV must be applied; and
- Unless both aircraft are radar identified, both aircraft must provide DME/RNAV distance reports via direct voice that indicates the appropriate separation exists; and
- Application of DME/RNAV separation without direct voice communications may not continue for more than 90 minutes; and
- The preceding aircraft is assigned the same or greater Mach number than the following aircraft; and
- Both aircraft must be advised of the other aircraft involved, including the distance relative to the flights.
- “Maintain Mach point eight four, same direction traffic,twelve o’clock, three five miles.”