Section 4. Longitudinal Separation
6-4-1. APPLICATION
Separate aircraft longitudinally by requiring them to
do one of the following, as appropriate:
a. Depart at a specified time.
b. Arrive at a fix at a specified time.
PHRASEOLOGY-
CROSS (fix) AT OR BEFORE (time).
CROSS (fix) AT OR AFTER (time).
c. Hold at a fix until a specified time.
d. Change altitude at a specified time or fix.
REFERENCE-
FAAO JO 7110.65, Para 4-5-7, Altitude Information.
6-4-2. MINIMA ON SAME, CONVERGING,
OR CROSSING COURSES
Separate aircraft on the same, converging, or crossing
courses by an interval expressed in time or distance,
using the following minima:
a. When the leading aircraft maintains a speed at
least 44 knots faster than the following aircraft -
5 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, or 3 minutes between other aircraft
if, in either case, one of the following conditions is
met:
1. A departing aircraft follows a preceding
aircraft which has taken off from the same or adjacent
airport. (See FIG 6-4-1.)
FIG 6-4-1
Minima on Same Course
44 Knots or More Separation
2. A departing aircraft follows a preceding
en route aircraft which has reported over a fix serving
the departure airport. (See FIG 6-4-2.)
FIG 6-4-2
Minima on Converging Courses
44 Knots or More Separation
3. An en route aircraft follows a preceding en
route aircraft which has reported over the same fix.
(See FIG 6-4-3.)
FIG 6-4-3
Minima on Crossing Courses
44 Knots or More Separation
b. When the leading aircraft maintains a speed at
least 22 knots faster than the following aircraft -
10 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; or 5 minutes between other aircraft
if, in either case, one of the following conditions
exists:
1. A departing aircraft follows a preceding
aircraft which has taken off from the same or an
adjacent airport. (See FIG 6-4-4.)
FIG 6-4-4
Minima on Same Course
22 Knots or More Separation
2. A departing aircraft follows a preceding
en route aircraft which has reported over a fix serving
the departure airport. (See FIG 6-4-5.)
FIG 6-4-5
Minima on Converging Courses
22 Knots or More Separation
3. An en route aircraft follows a preceding
en route aircraft which has reported over the same fix.
(See FIG 6-4-6.)
FIG 6-4-6
Minima on Crossing Courses
22 Knots or More Separation
c. When an aircraft is climbing or descending
through the altitude of another aircraft:
1. 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- 10 miles, if the descending aircraft
is leading or the climbing aircraft is following.
(See FIG 6-4-7 and FIG 6-4-8.)
FIG 6-4-7
Descending Through Another Aircraft's
Altitude DME Separation
FIG 6-4-8
Climbing Through Another Aircraft's
Altitude DME Separation
2. Between other aircraft- 5 minutes, if all of the
following conditions are met:
(See FIG 6-4-9 and FIG 6-4-10.)
(a) The descending aircraft is leading or
climbing aircraft is following.
(b) The aircraft are separated by not more
than 4,000 feet when the altitude change started.
(c) The change is started within 10 minutes
after a following aircraft reports over a fix reported
over by the leading aircraft or has acknowledged a
clearance specifying the time to cross the same fix.
3. Between RNAV aircraft that are operating
along an RNAV route that is eight miles or less in
width- 10 miles provided the following conditions
are met:
(a) The descending aircraft is leading or the
climbing aircraft is following.
(b) The aircraft were separated by not more
than 4,000 feet when the altitude change started.
FIG 6-4-9
Descending Through Another
Aircraft's Altitude Timed Separation
FIG 6-4-10
Climbing Through Another
Aircraft's Altitude Timed Separation
d. When the conditions of subparas a, b, or c
cannot be met- 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; or 10 minutes
between other aircraft.
(See FIG 6-4-11, FIG 6-4-12, FIG 6-4-13,
FIG 6-4-14, FIG 6-4-15, and FIG 6-4-16.)
FIG 6-4-11
Minima for Same Course Separation
FIG 6-4-12
Minima for Crossing Courses Separation
FIG 6-4-13
Minima for Same Course Separation
FIG 6-4-14
Minima for Crossing Courses Separation
FIG 6-4-15
Climbing Through Another
Aircraft's Altitude Separation
FIG 6-4-16
Descending Through Another
Aircraft's Altitude Separation
e. Between aircraft, when one aircraft is using
DME/ATD and the other is not- 30 miles if both the
following conditions are met:
(See FIG 6-4-17 and FIG 6-4-18.)
FIG 6-4-17
Minima for Same Course Separation
FIG 6-4-18
Minima for Crossing Courses Separation
1. The aircraft using DME/ATD derives distance information by reference to the same NAVAID
or waypoint over which the aircraft not using
DME/ATD has reported.
2. The aircraft not using DME/ATD is within
15������minutes of the NAVAID.
6-4-3. MINIMA ON OPPOSITE COURSES
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.)
FIG 6-4-19
Minima for Opposite Courses Separation
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.
a. Both aircraft have reported passing NAVAIDs,
DME fixes, or waypoints indicating they have passed
each other. (See FIG 6-4-20.)
FIG 6-4-20
Minima for Opposite Courses Separation
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.
b. Both aircraft have reported passing the same
intersection/waypoint and they are at least 3 minutes
apart.
c. Two RNAV aircraft have reported passing the
same position and are at least 8 miles apart if
operating along a route that is 8 miles or less in width;
or 18 miles apart if operating along an expanded
route; except that 30 miles must be applied if
operating along that portion of any route segment
defined by a navigation station requiring extended
usable distance limitations beyond 130 miles.
d. An aircraft utilizing RNAV and an aircraft
utilizing VOR have reported passing the same
position and the RNAV aircraft is at least 4 miles
beyond the reported position when operating along a
route that is 8 miles or less in width; 9 miles beyond
the point when operating along an expanded route;
except that 15 miles must be applied if operating
along that portion of any route segment defined by a
navigation station requiring extended usable distance
limitation beyond 130 miles; or 3 minutes apart
whichever is greater.
NOTE-
Except for GNSSequipped aircraft /G, /L, /S, and /V, not on
a random impromptu route, Paragraph 551, Application,
requires radar separation be provided to RNAV aircraft
operating at and below FL450 on Q routes or random
RNAV routes, excluding oceanic airspace.
6-4-4. SEPARATION BY PILOTS
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.
PHRASEOLOGY-
MAINTAIN AT LEAST ONE ZERO MINUTES/TWO ZERO MILES SEPARATION FROM (ident).
6-4-5. RNAV AIRCRAFT ALONG VOR
AIRWAYS/ROUTES
Advise the pilot to use DME distances when applying
DME separation to an RNAV aircraft operating along
VOR airways/routes.
PHRASEOLOGY-
USE DME DISTANCES.
NOTE-
ATD derived from area navigation devices having
slant-range correction will not coincide with the direct
DME readout.
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