Longitudinal Separation in Oceanic Control

Vocabulary flashcards covering longitudinal separation standards for same and opposite direction aircraft, including time-based, distance-based, and airspace reservation criteria as of 2025.

Longitudinal Separation Minima (Same Direction)

The spacing maintained between the estimated positions of aircraft flying along the same direction tracks throughout the period where lateral separation does not exist.

Common Point (Automated Conflict Prediction)

A real or system-calculated point used to center longitudinal separation calculations for same direction aircraft where automated conflict prediction capability exists.

5-Minute Time-Based Separation Criteria

Applied if aircraft are RNP 4, RCP 240, and RSP 180 approved, with ADS-C position reports at FOM 6 or higher, and no reports more than $6\,\text{minutes}$ overdue.

BIRD Data Link Transition Tolerance

A temporary period of approximately $10\,\text{minutes}$ allowed for establishing a data link connection after an aircraft enters BIRD before another form of separation must be applied.

5-Minute GNSS Climbing/Descending Separation

Applied between GNSS equipped aircraft if the level change begins within $10\,\text{minutes}$ of the second aircraft reporting over a common point and vertical separation is $\le 4000\,\text{feet}$.

9-Minute Mach Number Technique

Required longitudinal separation when the preceding aircraft is Mach $0.02$ faster than the following aircraft.

8-Minute Mach Number Technique

Required longitudinal separation when the preceding aircraft is Mach $0.03$ faster than the following aircraft.

7-Minute Mach Number Technique

Required longitudinal separation when the preceding aircraft is Mach $0.04$ faster than the following aircraft.

6-Minute Mach Number Technique

Required longitudinal separation when the preceding aircraft is Mach $0.05$ faster than the following aircraft.

5-Minute Mach Number Technique

Required longitudinal separation when the preceding aircraft is Mach $0.06$ faster than the following aircraft.

Domestic Area Longitudinal Minimum

$10\,\text{minutes}$ between aircraft at the same altitude.

10-Minute ADS-C Separation

Applicable for aircraft on same or intersecting tracks with ADS-C periodic contracts of a maximum $20\,\text{minutes}$ reporting interval.

ADS-C Report Action Timeframes

The controller must take action within $3\,\text{minutes}$ of a missed ADS-C periodic report and apply alternative separation if communication isn't established within $6\,\text{minutes}$.

20 NM Distance-Based Separation

A GNSS/DME minimum applied when both aircraft are in direct VHF contact and utilize the same on-track DME station, collocated waypoint, or the same waypoint.

10 NM Distance-Based Separation

A GNSS/DME minimum applied if one aircraft maintains a level and the relative angle between tracks is less than $45$ degrees.

Opposite Direction Longitidinal Separation

A requirement where vertical separation is provided during a period equal to the appropriate minimum prior to and after aircraft are estimated to meet.

15-Minute Opposite Direction Separation

The vertical separation interval required before and after the estimated passing time for opposite direction aircraft that have not reported over a common point.

5 NM Opposite Direction Distance Separation

A surveillance-based minimum allowing the discontinuation of vertical separation once reports demonstrate aircraft have passed with a relative track angle between $136$ and $224$ degrees.

10 NM Opposite Direction Distance Separation

A DME/GNSS minimum allowing the discontinuation of vertical separation once reports from a common point show aircraft have passed with a relative track angle between $136$ and $224$ degrees.

Airspace Reservation (ALTRV) Minimum

A longitudinal separation of $60\,\text{minutes}$ maintained between moving airspace reservations.

AVANA (ALTRV Void if Aircraft Not Airborne by)

A time used to calculate longitudinal separation where $60\,\text{minutes}$ must be maintained between the latest time of the first reservation and the earliest time of the second.