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AIM 

6/17/21 

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. 

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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. 

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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. 

Wake Turbulence 

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