Wake Turbulence
Back in the early 1960s I was a young lieutenant navigator assigned to a KC-135 air refueling squadron at Ellsworth AFB, near Rapid City, South Dakota. I was also a member of the base aero club and piloted Cessna 150s recreationally. Frequently there were B-52s and KC-135s in Ellsworth’s traffic pattern, but the little aero club birds seemed to stay out of the way of the big boys.
I was already familiar with the effects of wake turbulence because of a particular bit of training every SAC combat crew had to go through: the Minimum Interval Takeoff, or MITO. The MITO was technique for getting a lot of aircraft off the ground in the shortest span of time. In a MITO practice session, three or more aircraft with similar gross weight and acceleration characteristics would begin their takeoff rolls separated by only 15 seconds. It was a thrilling enough ride on just the takeoff roll with all the smoke, noise and buffeting of three or more aircraft on the runway at the same time. The minute or so after rotate and liftoff was even more thrilling. There almost always was a lot of roll and yaw as each aircraft plowed through the wake turbulence of everyone out in front.
On one particularly calm Saturday morning I was in a Cessna 150 and heading out to Runway 30, Ellsworth’s active runway. Most Saturdays were quiet, but on this particular Saturday, at the particular moment I approached the hold line, a KC-135 going somewhere was roaring down the runway on takeoff roll. The little Cessna shuddered a bit as the -135 went by and rotated a short distance beyond where I was holding. I watched as the -135 retracted its landing gear and begin the accelerate. At that moment Ellsworth tower cleared me for takeoff, but being familiar with wake turbulence, I decided to wait a couple of minutes for things to settle down. I could see the smoky exhaust from the -135 still roiling about on the runway. A couple of minutes later I took the runway and started my takeoff roll. I was hugging the left side of the 200 foot-wide runway, trying to stay out of whatever residual turbulence might still be around.
Everything seemed to be working out as planned until I had climbed, maybe, 100 feet above the runway. Then the wake turbulence from the recently departed KC-135 snapped the little Cessna into a steep left bank. It was an incredibly powerful motion, as if a giant hand had reached under the right wing and slapped it upward. I don’t know how steep of a bank I was in, but the horizon suddenly was very much askew. I didn’t try to roll the wings back to level; to do that would mean staying in the turbulence. Instead I pulled back on the control wheel and tried to get as far away from that runway centerline as fast as I could. In just a few seconds, I was far enough away from the r7unway that wake turbulence was no long a problem. Only then did I bring the wings back to level. Later it occurred to me that if I had taken off when I had been given clearance I might have ended up inverted rather that in a steep bank. What a scary thought.
Go Around
This is an incident that happened because someone didn’t use common sense. The scene is forty years ago at Rapid City airport, the local civilian airport near Ellsworth AFB. There were several light aircraft in the traffic pattern, Cessnas and Pipers, mostly. At the controls of most of the aircraft were student pilots who were getting in some solo time in preparation for their private pilot exams. One student had just soloed. Also in the pattern was one of our flight surgeons who had a real taste for flying. We’ll call him Doc. He was a private pilot with an instrument rating. He also had enough extra money to take out the only aero club aircraft that featured retractable landing gear and a constant speed prop. It was a Beechcraft T-34 “Mentor” that the Air Force had turned over to the aero club.
Just like all the student pilots on this particular spring day, Doc was in the traffic pattern shooting touch and goes, and generally sharpening his piloting skills. The recently soloed student pilot was behind Doc in the traffic pattern. Each time Doc turned onto his final approach leg, the student behind him made his own turn to base a bit earlier than the previous circuit. Slowly, he was cutting Doc off and shortening the distance between them in the traffic pattern. Things came to a critical point when Doc decided that rather than doing another touch and go, he would do a full stop and turn off the runway. The student pilot, now very close behind Doc didn’t know what to do. There was one obvious thing to do: Go Around. Unfortunately, the student didn’t think it.
Doc had slowed and was turning off at a taxiway, the student was close to touchdown right behind Doc’s T-34. The student did the only thing he could think of doing; he covered his eyes and let the Cessna contact the runway on its own. The Cessna hit the runway, nose wheel first, and pranged back into the air, hopping half over and half past Doc’s slowly taxiing T-34. The Cessna missed the T-34, but it gave Doc a real start to see this Cessna go bouncing past him. Needless to say, the Cessna was a bit the worse for wear, and the student decided that he had enough of flying.
Gerald P. Hanner
gphanner@cox.net
