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AIM

10/12/17

7−3−6

Wake Turbulence

below the larger aircraft’s flight path. Abandon the

approach unless a landing is ensured well before

reaching the intersection.

6. Departing behind a larger aircraft. Note

the larger aircraft’s rotation point and rotate prior to

the larger aircraft’s rotation point. Continue climbing

above the larger aircraft’s climb path until turning

clear of the larger aircraft’s wake. Avoid subsequent

headings which will cross below and behind a larger

aircraft. Be alert for any critical takeoff situation

which could lead to a vortex encounter.

7. Intersection takeoffs− same runway. Be

alert to adjacent larger aircraft operations, particular-

ly upwind of your runway. If intersection takeoff

clearance is received, avoid subsequent heading

which will cross below a larger aircraft’s path.

8. Departing or landing after a larger

aircraft executing a low approach, missed

approach, or touch−and−go landing. Because

vortices settle and move laterally near the ground, the

vortex hazard may exist along the runway and in your

flight path after a larger aircraft has executed a low

approach, missed approach, or a touch−and−go

landing, particular in light quartering wind condi-

tions. You should ensure that an interval of at least

2 minutes has elapsed before your takeoff or landing.

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. Government and industry groups are making

concerted efforts to minimize or eliminate the

hazards of trailing vortices. However, the flight

disciplines necessary to ensure vortex avoidance

during VFR operations must be exercised by the pilot.

Vortex visualization and avoidance procedures

should be exercised by the pilot using the same degree

of concern as in collision avoidance.

b. Wake turbulence may be encountered by

aircraft in flight as well as when operating on the

airport movement area.

REFERENCE−

Pilot/Controller Glossary Term− Wake Turbulence.

c. Pilots are reminded that in operations conducted

behind all aircraft, acceptance of instructions from

ATC in the following situations is an acknowledg-

ment that the pilot will ensure safe takeoff and

landing intervals and accepts the responsibility for

providing wake turbulence separation.

1. Traffic information.
2. Instructions to follow an aircraft; and
3. The acceptance of a visual approach

clearance.

d. 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.

e. 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.