AIM
4/3/14
7−3−7
Wake Turbulence
2.
Pilots of aircraft that produce strong wake
vortices should fly as closely as possible to the
approach course centerline or to the extended
centerline of the runway of intended landing as
appropriate to conditions.
f.
Pilots operating lighter aircraft on visual
approaches in−trail to aircraft producing strong wake
vortices should use the following procedures to assist
in avoiding wake turbulence. These procedures apply
only to those aircraft that are on visual approaches.
1.
Pilots of lighter aircraft should fly on or
above the glidepath. Glidepath reference may be
furnished by an ILS, by a visual approach slope
system, by other ground−based approach slope
guidance systems, or by other means. In the absence
of visible glidepath guidance, pilots may very nearly
duplicate a 3−degree glideslope by adhering to the
“3 to 1” glidepath principle.
EXAMPLE
−
Fly 3,000 feet at 10 miles from touchdown, 1,500 feet at
5 miles, 1,200 feet at 4 miles, and so on to touchdown.
2.
If the pilot of the lighter following aircraft has
visual contact with the preceding heavier aircraft and
also with the runway, the pilot may further adjust for
possible wake vortex turbulence by the following
practices:
(a)
Pick a point of landing no less than
1,000 feet from the arrival end of the runway.
(b)
Establish a line−of−sight to that landing
point that is above and in front of the heavier
preceding aircraft.
(c)
When possible, note the point of landing
of the heavier preceding aircraft and adjust point of
intended landing as necessary.
EXAMPLE
−
A puff of smoke may appear at the 1,000
−foot markings of
the runway, showing that touchdown was that point;
therefore, adjust point of intended landing to the
1,500
−foot markings.
(d)
Maintain the line−of−sight to the point of
intended landing above and ahead of the heavier
preceding aircraft; maintain it to touchdown.
(e)
Land beyond the point of landing of the
preceding heavier aircraft.
3.
During visual approaches pilots may ask ATC
for updates on separation and groundspeed with
respect to heavier preceding aircraft, especially when
there is any question of safe separation from wake
turbulence.
7
−
3
−
9. Air Traffic Wake Turbulence
Separations
a.
Because of the possible effects of wake
turbulence, controllers are required to apply no less
than specified minimum separation for aircraft
operating behind a heavy jet and, in certain instances,
behind large nonheavy aircraft (i.e., B757 aircraft).
1.
Separation is applied to aircraft operating
directly behind a heavy/B757 jet at the same altitude
or less than 1,000 feet below:
(a) Heavy
jet behind heavy jet−4 miles.
(b) Large/heavy
behind B757 − 4 miles.
(c) Small
behind B757 − 5 miles.
(d) Small/large
aircraft behind heavy jet −
5 miles.
2.
Also, separation, measured at the time the
preceding aircraft is over the landing threshold, is
provided to small aircraft:
(a) Small
aircraft landing behind heavy jet −
6 miles.
(b) Small
aircraft landing behind B757 −
5 miles.
(c) Small
aircraft landing behind large
aircraft− 4 miles.
REFERENCE
−
Pilot/Controller Glossary Term
− Aircraft Classes.
3.
Additionally, appropriate time or distance
intervals are provided to departing aircraft:
(a)
Two minutes or the appropriate 4 or 5 mile
radar separation when takeoff behind a heavy/B757
jet will be:
(1)
From the same threshold.
(2)
On a crossing runway and projected
flight paths will cross.
(3)
From the threshold of a parallel runway
when staggered ahead of that of the adjacent runway
by less than 500 feet and when the runways are
separated by less than 2,500 feet.
NOTE
−
Controllers may not reduce or waive these intervals.