Mark:
"In this session, we will discuss the issues of wake turbulence specific to landing."
Bob:
"We need to note the preceding aircraft's touchdown point, particularly if it is a large aircraft. And we need to land after that touchdown point. Our glide path should at all times be above the glide path of the preceding aircraft, and be to the upwind side, so again, we need to know where the wind is coming from, which side of the aircraft the wind is from. We want to be on that upwind side. Again, glide path above, touch down after the point of touchdown in the preceding aircraft.
Well, how do we know we are in fact, above the glide path of the preceding aircraft? There are a number of ways to do it. One, if you have a glide slope capability in your airplane, note where you are on the glide slope of that runway, if it in fact, has an ILS installation. If it has PAPI or VASI lights, try to be slightly above that glide path. Again, you are assuming that the preceding aircraft is, in fact, on glide path."
Mark:
"What if there is no glide path information available?"
Bob:
"I will tell you a method that I use to establish whether I am at, below, or above the glide path in a preceding aircraft. It is pretty simple. Sight through the preceding aircraft to the runway. Note the touchdown zone markings on the runway and where your sight line intersects the runway. If it intersects beyond the touchdown zone markings on the runway, you are below the glide path of the preceding aircraft. If it intersects -- if that sight line intersects prior to the touchdown zone that is painted on the runway, your glide path is above the preceding aircraft.
That works pretty good, because you want to stay above the glide path. I can tell you personally that this is really important because many years ago, I had a wake turbulence encounter after following a large aircraft by approximately four miles and making an honest effort to stay above the glide path which I did almost to the touch down point.
I was in a Bonanza landing behind a 767 at dusk, very little wind to disperse any wake turbulence. I carried the high glide path down over the threshold then chopped the power and descended to the runway. Well, this took me right through the wake turbulence of that 767 and the Bonanza that I was flying rolled 90 degrees at probably an altitude of 150 feet.
Fortunately I was able to right the airplane and get it down on the runway, but I will tell you what, when I got out of the airplane I had a pair of wobbly knees, so that taught me a lesson. Do not give up on it until you touch down and touch down beyond the point of touch down of that preceding aircraft."
Source: http://www.pilotworkshop.com/tips/wake_turbulence_landing.htm
