Wake Turbulence Avoidance

by Josh on February 23, 2012

Wake Turbulence is something you just don’t want to mess with. It seems to some pilots to be that invisible nightmare. In the last 5 years, there have been over 500 fatalities and accidents related to wake turbulence.  So here is what to do if you ever come across it.

What is Wake Turbulence?  Well, wake turbulence is the vortices coming off of the wingtips of aircraft. Only when the nose wheel of that particular aircraft leaves the ground is it creating lift therefore producing wake turbulence or wingtip vortices.  The vortices can be best described as tornados, spiraling off from the wingtips. Wake turbulence also descends and goes with the wind. This is why it is so important to know where the wind is at. Wake Turbulence generally can descend anywhere from 500-1000 ft.

Avoiding Wake Turbulence. There are three different situations that you might encounter with wake turbulence an here are some ways to deal with them all.

Say you are holding short and say a Boeing 747 just took off, what do you do? This happens to many pilots and most are not completely sure of what to do. There are a few options.  You want to make sure you look for his or her point of rotation, because these vortices do not start until he rotates and starts generating lift. One of your options is to taxi down the runway a bit until you will take off after his point of rotation. Another option if you can is to rotate before him and turnout as quick as possible. Your last option is to ask the controller for your three minutes. What this means is that if you are unsure or uncomfortable about taking off after there might have been wake turbulence, you can wait at the runway for three minutes before taking off. The controllers are required to let you do this no matter how many other aircraft are behind you waiting.

Another situation: A B747 just landed as you are holding short to take off, what do you do? Well remember, that the other aircrafts wake turbulence ends on their touchdown because that is when lift stops being produced. So make sure you take into account where his touchdown point is. The things to do are pretty much the same as above. You can taxi down the runway until after the B747’s touchdown point. This is a good option when you have a long enough runway to taxi down a couple hundred feet and still be able to takeoff. Or you can ask the controller for your three minutes. Which makes sense when you don’t have enough runway to taxi down it, or when you just aren’t comfortable and want to wait those vortices out a little.

The last situation: There is a B747 on final approach and you just got cleared to land behind it. This is probably the most dangerous of the three situations because you are at such a low altitude and so slow. What you can do to avoid the wake on landing is a little different than what you can do on takeoff. Make sure you look for his touchdown point so you know where those vortices end. The thing to do to avoid them is stay above his glide path. If you stay above the glide path, you will stay above the wake. It might be difficult to stay above a B747’s glide path, but remember you can always touchdown the runway a little farther than usual if needed. Also, make sure that you touchdown after his touchdown point, because that is where the vortices end.

Wake turbulence can be a nightmare if you don’t know how to properly handle it and what to do if you come across it. But if you are well prepared, it will be like it was never even there. So next time you hear that controller tell you “caution wake turbulence”, don’t just ignore it. Take it very seriously, because it could ruin your day.

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