Wake turbulence

It includes several components, the most significant of which are wingtip vortices and jet-wash, the rapidly moving gases expelled from a jet engine.

Tests have also shown that the vortices sink at a rate of several hundred feet per minute, slowing their descent and diminishing in strength with time and distance behind the generating aircraft.

[6] ICAO mandates wake turbulence categories based upon the maximum takeoff weight (MTOW) of the aircraft.

There are a number of separation criteria for take-off, landing, and en-route phases of flight based upon wake turbulence categories.

The aircraft making a visual approach is advised of the relevant recommended spacing and are expected to maintain their separation.

[7]: 9 During takeoff and landing, an aircraft's wake sinks toward the ground and moves laterally away from the runway when the wind is calm.

In 2020, researchers looked into installing "plate lines" near the runway threshold to induce secondary vortices and shorten the vortex duration.

Currently, ICAO recognizes two methods of measurement, sound tomography, and a high-resolution technique, the Doppler lidar, a solution now commercially available.

[25] On a still day, the wake turbulence from heavy jets on landing approach can be heard as a dull roar or whistle.

In the movie Pushing Tin, air traffic controllers stand just off the threshold of a runway while an aircraft lands in order to experience wake turbulence firsthand.

However, the film dramatically exaggerates the effect of turbulence on persons standing on the ground, showing the protagonists being blown about by the passing aircraft.

This picture from a NASA study on wingtip vortices qualitatively illustrates the wake turbulence.
A helicopter taxiing to its parking area and blowing up loose snow into the air
Wake vortices from a landing Airbus at Oakland International Airport interact with the sea as they descend to ground level.
Glider pilots usually fly outside the wake turbulence generated by their tow planes, either above the wake (high tow) or below the wake (low tow). [ 8 ]
XB-70 62-0207 following the midair collision on 8 June 1966.