Originally Posted by
PearlPilot
When an aircraft is heavy, clean, and slow, wake turbulence caused by wing tip vortices poses an extreme hazard for aircraft. We all learned that in ground school. Since the illustration in textbooks usually has a large airliner, I always thought this was a phenomenon related only to "big" airplanes right? Suppose you are flying a 172, and can prop blast and wake turbulence of another 172 (say on final approach) be a hazard on a calm day? As a student pilot on a cross country, a Saab 340 departed and the tower warned me about wake turbulence from the departing Saab. I though it was interesting. So I executed a textbook take off and rotated prior to the Saab's rotation point. Only yesterday a Diamond Eclipse Jet took off and the tower immediately gave me clearance to go (while the baby jet was lifting off). Hmm...I said I need about a minute for the wake to dissipate. The tower acknowledged (with a slight hint of a chuckle) "no problem, just let me know when you are ready." I felt a little silly, but as a PIC it is ultimately my responsibility so you can laugh at me all you want, I thought. If a 747 took off, well then it's a different story. All in all, I have to admit, I am a little confused here at least when it comes to wake turbulence and "small" planes. Does it exist to such an extent as to pose a threat?
All aircraft generate wake turbulence. Generally speaking, aircraft are not adversely affected by wake turbulence created by a similar aircraft. However, when in doubt, wait as you did.
Also remember that wake turbulence is a by-product of lift. Prior to lift being generated at rotation there is no wake turbulence. So, even if you are behind a larger aircraft, if you can rotate before he did you will be above his wake turbulence. Just be cognizant of possibly flying through it once airborne. The easiest way to avoid that is stay above his climb path or alter your ground track slightly upwind of his.