PILOT TRAINING ARTICLE



Turbulence



airplane wake vortex turbulence
 
It’s a clear and a million day. You’ve been flying VFR at 10,500 feet for the past two hours and after a rather uneventful flight, are beginning to prepare for your upcoming descent and approach into your destination. Suddenly the right wing dips, rolling the aircraft into a 30 degree right bank. Just as quickly, the aircraft snap-rolls back left, this time putting you into an almost 90 degree left bank.
 
While hopefully most of us will never experience something as dramatic as this in our lifetimes, it is certainly not an unheard of occurrence. Such instances do happen and can pose a significant challenge to pilots. In the case of the above situation, the turbulence encountered was actually wake turbulence generated from a C-5 cargo aircraft that had transited the area five minutes prior. Yes, read that again. The aircraft that caused the turbulence was five minutes ahead of the affected airplane. Doing some quick math, at a speed of, say, 260 knots, that would put the C-5 nearly 25 miles away! This just goes to show how dangerous and unexpected turbulence can be.
 
I used to scoff at the “please keep seatbelts fastened when seated, even if the ‘fasten seatbelt’ sign is not lit” message on airline flights. However, I never do now. Can you imagine what would happen to a passenger or crew member out of their seats during such an episode as that which was described above?
 
Bottom line, turbulence is not something to take lightly. Know your aircraft’s numbers, and remember the procedures for encountering turbulence. Slow (or speed up) to turbulence penetration speed and ride out the bumps. Do not attempt to fight the turbulence because you will lose and may overstress the aircraft. For me, I liken turbulence encounters to black-ice while driving. If you hit such a patch of ice you should take your foot off of the brake or accelerator and not attempt to steer; just drive through and let the car recover itself. This is the same for the aircraft.
 
And, you may ask, what happened to the aircraft in the above scenario? Well recognizing that his plane had encountered wake turbulence, the pilot flying executed a recovery back to wings level by a quick, smooth application of right rudder. He was back upright and, albeit a little shaken