Separate aircraft longitudinally by requiring them to do one of the following, as appropriate:
Separate aircraft on the same, converging, or crossing courses by an interval expressed in time or distance, using the following minima:
Separate aircraft traveling opposite courses by assigning different altitudes consistent with the approved vertical separation from 10 minutes before, until 10 minutes after they are estimated to pass. Vertical separation may be discontinued after one of the following conditions is met: (See FIG 6-4-19.)
NOTE: RNAV route segments that have been expanded in the proximity to reference facilities for slant-range effect are not to be considered “expanded” for purposes of applying separation criteria in this paragraph.
NOTE: It is not intended to limit application of this procedure only to aircraft operating in opposite directions along the same airway or radial. This procedure may also be applied to aircraft established on diverging airways or radials of the same NAVAID.
NOTE: Except for GNSS-equipped aircraft /G, /L, /S, and /V, not on a random impromptu route, Paragraph 5-5-1, Application, requires radar separation be provided to RNAV aircraft operating at and below FL450 on Q routes or random RNAV routes, excluding oceanic airspace.
When pilots of aircraft on the same course in direct radio communication with each other concur, you may authorize the following aircraft to maintain longitudinal separation of 10 minutes; or 20 miles between DME equipped aircraft; RNAV equipped aircraft using ATD; and between DME and ATD aircraft provided the DME aircraft is either 10,000 feet or below or outside of 10 miles from the DME NAVAID.
Advise the pilot to use DME distances when applying DME separation to an RNAV aircraft operating along VOR airways/routes.
NOTE: ATD derived from area navigation devices having slant-range correction will not coincide with the direct DME readout.