AIM Text
- A wake turbulence encounter can range from negligible to catastrophic. The impact of the encounter depends on the weight, wingspan, size of the generating aircraft, distance from the generating aircraft, and point of vortex encounter. The probability of induced roll increases when the encountering aircraft's heading is generally aligned with the flight path of the generating aircraft.
- AVOID THE AREA BELOW AND BEHIND THE WAKE GENERATING AIRCRAFT, ESPECIALLY AT LOW ALTITUDE WHERE EVEN A MOMENTARY WAKE ENCOUNTER COULD BE CATASTROPHIC.
- Pilots should be particularly alert in calm wind conditions and situations where the vortices could:
- Remain in the touchdown area.
- Drift from aircraft operating on a nearby runway.
- Sink into the takeoff or landing path from a crossing runway.
- Sink into the traffic pattern from other airport operations.
- Sink into the flight path of VFR aircraft operating on the hemispheric altitude 500 feet below.
- Pilots should attempt to visualize the vortex trail of aircraft whose projected flight path they may encounter. When possible, pilots of larger aircraft should adjust their flight paths to minimize vortex exposure to other aircraft.
Source: FAA Aeronautical Information Manual · current edition · paragraph 7-4-5.
The short answer
AIM 7-4-5 is FAA advisory guidance on wake turbulence problem areas. It warns that encounters worsen below and behind the generating aircraft, especially at low altitude, and lists scenarios—calm wind, crossing or nearby runways, and en route VFR traffic 500 feet below—where vortices can persist or drift into a pilot's path.
Research Notes
Common Questions
When am I most likely to hit wake turbulence on a visual approach?
AIM 7-4-5 notes a common scenario is terminal airspace after accepting a visual approach clearance behind landing traffic. Pilots must track their position relative to that traffic and use all means of vertical guidance to avoid flying below the wake generating aircraft's flight path.
How long should I wait after a larger aircraft does a low approach or touch-and-go?
Because vortices settle and move laterally near the ground, AIM 7-4-5 advises ensuring an interval of at least 2 minutes has elapsed before your takeoff or landing, particularly in light quartering wind conditions.
What conditions make vortices most likely to stay in the touchdown area?
AIM 7-4-5 says pilots should be particularly alert in calm wind conditions, when vortices can remain in the touchdown area, drift from a nearby runway, sink from a crossing runway, or sink into the flight path of VFR aircraft on the hemispheric altitude 500 feet below.