AIM
8/15/19
7
−
3
−
6
Wake Turbulence
9. En route VFR (thousand
−
foot altitude plus
500 feet).
Avoid flight below and behind a large
aircraft’s path. If a larger aircraft is observed above on
the same track (meeting or overtaking) adjust your
position laterally, preferably upwind.
7
−
3
−
7. Helicopters
In a slow hover taxi or stationary hover near the
surface, helicopter main rotor(s) generate downwash
producing high velocity outwash vortices to a
distance approximately three times the diameter of
the rotor. When rotor downwash hits the surface, the
resulting outwash vortices have behavioral character-
istics similar to wing tip vortices produced by fixed
wing aircraft. However, the vortex circulation is
outward, upward, around, and away from the main
rotor(s) in all directions. Pilots of small aircraft
should avoid operating within three rotor diameters
of any helicopter in a slow hover taxi or stationary
hover. In forward flight, departing or landing
helicopters produce a pair of strong, high
−
speed
trailing vortices similar to wing tip vortices of larger
fixed wing aircraft. Pilots of small aircraft should use
caution when operating behind or crossing behind
landing and departing helicopters.
7
−
3
−
8. Pilot Responsibility
a.
Research and testing have been conducted, in
addition to ongoing wake initiatives, in an attempt to
mitigate the effects of wake turbulence. Pilots must
exercise vigilance in situations where they are
responsible for avoiding wake turbulence.
b.
Pilots are reminded that in operations con-
ducted behind all aircraft, acceptance of instructions
from ATC in the following situations is an
acknowledgment that the pilot will ensure safe
takeoff and landing intervals and accepts the
responsibility for providing wake turbulence separa-
tion.
1.
Traffic information.
2.
Instructions to follow an aircraft; and
3.
The acceptance of a visual approach
clearance.
c.
For operations conducted behind
super
or
heavy
aircraft, ATC will specify the word “
super
” or
“
heavy
” as appropriate, when this information is
known. Pilots of
super
or
heavy
aircraft should
always use the word “
super
” or “
heavy
” in radio
communications.
d.
Super, heavy, and large jet aircraft operators
should use the following procedures during an
approach to landing. These procedures establish a
dependable baseline from which pilots of in
−
trail,
lighter aircraft may reasonably expect to make
effective flight path adjustments to avoid serious
wake vortex turbulence.
1.
Pilots of aircraft that produce strong wake
vortices should make every attempt to fly on the
established glidepath, not above it; or, if glidepath
guidance is not available, to fly as closely as possible
to a “3
−
1” glidepath, not above it.
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.
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.
e.
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.