More on wake turbulence

Wake turbulence 2A short while ago, I published an item about the disastrous effects of taking off too soon behind a heavier aircraft – ‘The dangers of wake turbulence

In that article, the advice was simple – bide your time and wait at least 2 minutes before taking off after a heavier aircraft. But here’s a bit more detailed advice from CFI Bob Nardiello, who has over 12,000 hours of flight experience (including 8,000+ hours of instruction). Bob was 2004 Flight Instructor of the Year and 2006 FAA Safety Counselor of the Year.

His advice on wake turbulence take-offs:

“Vortices tend to move outward from the aircraft. So if you are behind a departing aircraft, the vortex from the right wing will tend to move to the right and the vortex from the left wing will tend to move to the left – in nil wind conditions.

If there is a crosswind, the wind will influence the movement of the vortices. A crosswind of about 3 knots will hold the upwind vortex pretty much in place on the runway where it was created, while the downwind vortex will move rapidly away from the runway.

Wake turbulence 3Crosswinds greater than about 5 knots will tend to break up the vortices fairly quickly. So stronger crosswinds are good things, as far as vortices are concerned – we want the vortices to break up and decay as soon as possible. So light crosswinds around 3 knots and under require maximum caution.

We also need to note the lift-off point of the previous aircraft. That point is where the vortices will be developed. From that point on, there will be vortices off the wings of that departing aircraft. So it’s important that your take-off point occurs before the take-off point of the preceding aircraft. You DO NOT want to be taking off into the vortices of the preceding aircraft!

You need to climb on the upwind side of the departing aircraft to avoid the crosswind effect of the vortices. So if the crosswind will move the vortices to the left, your departure path should be to the right to avoid those vortices.”

So next time you’re taking off behind another aircraft, particularly a heavier one:
– lift off well before the take-off point of the preceding aircraft; if you can’t be sure to do this, WAIT!
– when you do take-off try to track to the upwind side of the earlier aircraft’s track.

Safe flying!

Information courtesy of Pilot Workshops

The dangers of wake turbulence

Wake turbulenceEver felt impatient to start your take-off quickly after a departing aircraft? Here’s a short video which might help your patience and perhaps even save your life.

In late 2012, a Robin DR400 low-wing light aircraft with four people on board was taking off from a grass strip in what seemed like perfect conditions. Suddenly the aircraft banked steeply to the right and in spite of full opposite aileron and rudder, the DR400 impacted the ground. About 45 seconds before, an Antonov AN-2 had taken off from the same runway.

Click the photo to see the video. I found the background music completely inappropriate but as everything is captioned on-screen, you can turn the music down or mute it.

Here’s a link to the full written report (in English): Wake turbulence hazard analysis

Our Light Sport and Recreational Aircraft are often much lighter than GA aircraft – so TAKE YOUR TIME and don’t take off for at least 2 minutes after another aircraft, particularly a heavier one in light wind conditions!

PS – the only time I experienced wake turbulence myself was at about 3,000 feet in a clear sky following about 200-300 metres behind another light sport aircraft. It happened very suddenly and felt like a huge hand had pulled hard down on one wing. Instinctively I applied opposite controls but for a long moment it made absolutely no difference. Thankfully I dropped out of the turbulence within seconds but it was one of the scariest moments of my flying life.