Wake turbulence is a very important concept for all pilots to understand due to the danger it poses.
All pilots should understand what wake turbulence is, how it is produced, what the effects are, and most importantly how to avoid it.
What is Wake Turbulence?
Wake turbulence is the turbulence that forms behind an aircraft as it moves through the air, causing wingtip vortices. It is generated from takeoff to landing – as soon as an aircraft’s wing produces lift and leaves the ground up until an aircraft lands. Wake turbulence affects aircraft of all weights.
The initial intensity is determined by several factors including configuration, speed, weight, wingspan, and angle of attack.
As a general rule, you can expect heavier aircraft to produce the strongest vortices when flying slowly at high angles of attack in a clean configuration – i.e. where there is lots of airspeed to generate lift and keep induced drag to a minimum.
What Are the Effects of Wake Turbulence?
Wake turbulence can affect nearby aircraft due to the strength and behavior of the vortices. It is particularly hazardous during take-off and landing due to there being insufficient altitude for recovery. Aircraft with short wingspans are most affected.
There are several factors that have an influence on just how hazardous wake turbulence can be. The most important factors include the weight and the wingspan of the aircraft behind, and relative positions of the wake vortices and aircraft.
At best – i.e. in its mildest form – wake turbulence can cause just slight rocking of the wings. At worst, it can cause a total loss of control of an aircraft.
The effects of wake turbulence are more greatly felt by smaller aircraft. Rolling in both directions is the most common scenario, though this can depend on the position of the trailing aircraft.
How to Avoid Wake Turbulence?
There are a few basic things to remember to deal with and avoid wake turbulence of leading aircraft:
- Do not get too close to the aircraft
- Do not get below the aircraft’s flight path
- Pay particular attention to when there are light wind conditions
- Though ordinary turbulence is not unusual, be weary of uncommanded aircraft movements
While recovery is dependent on the power of your aircraft, altitude, and maneuverability, use the Power-Push-Roll recovery technique.
- Power: At low altitudes or slow speed, increase the power
- Push: To reduce the angle of attack of the wings for better roll control, reduce drag for rolling over, and slow your descent towards the ground if you are rolling over, unload the wings or “push” on the control column. This may not always be possible during takeoff or landing when you are flying close to the ground
- Roll: Roll to the nearest horizon or in the direction that will reduce the loading on the wings, if possible
More specifically, there are ways to deal with wake turbulence during various stages of flight.
- Takeoff: Stay upwind of the touchdown point of the landing aircraft, and liftoff before the rotation point of the preceding aircraft
- Climb: Turn off the extended centreline as soon as you can if you are unable to out-climb the preceding aircraft’s flight path. If you are unable to out-climb and deviate from the aircraft’s flight path, track slightly upwind and parallel its course
- Following: Stay either on or above the preceding aircraft’s flight path
- Approach: Carefully consider whether you should accept a visual approach when you are close behind a large aircraft. Also do not automatically think that you are on the same or lower flight path as the aircraft you are following.
- Landing: Aim to land a good deal of time before a departing aircraft’s rotation point. If landing behind another aircraft, stay above that aircraft’s flight path and land beyond its landing point, if possible.