Flight Training - September 2011 - 44

FLIGHT LESSON

By Prasad Ganti

FLIGHT LESSON offers the opportunity for pilots to learn from the experiences of others.

THE RIGHT PLACE, TIME, AND AIRSPEED
got my private pilot certificate in a Cessna 152, then transitioned to flying a Cessna 172. I flew a few hours with an instructor to get used to the bigger airplane, then I spent a few hours flying by myself. I was used to taking my family and friends up in the 152. One day, a friend and his family visiting from India on a sightseeing trip to the United States were staying with us and expressed lots of interest in flying with me. Now I had a group of three people—and I had never flown a fully loaded 172 before.
On a nice, sunny afternoon, I departed from Princeton airport in New Jersey with my three passengers. They were thrilled to be up in the air, seeing all the different landmarks and big homes with swimming pools and tennis courts, highways, and lakes. Then the moment of truth came. I had to land the airplane and get my passengers safely to the ground. I did not worry much because the weather was sunny with a very slight wind. The final approach looked stable. At the point of touchdown, however, I bounced. After a couple of bounces, the airplane settled down. The airplane was in no danger at any time; it remained under control and we were on the centerline. We then taxied to the tiedown. Although my passengers were still cheerful and happy, one of them made a casual remark about the bounced landing and asked why it had happened. I did not have an answer, and confessed to a bad landing. The bounced landing bothered me and I decided to seek an answer for myself so that this would not happen in the future. I tried to recall the sequence of events— what I did, and when and why I did it. I also discussed it with my instructor, and I read a great deal about landings. Then it hit me like a ton of bricks. The problem was that, inadvertently, I was somehow married to the concept of coming down the final approach with the throttle almost

THE LANDING EQUATION

F I

closed; that is, with very minimal power— and my hands were pretty much off the throttle. It had worked well with a Cessna 152, a light airplane that can seat only one other person. It had worked fairly well in the Cessna 172 with just myself or possibly another person in the airplane. However, this theory started to break down if the airplane was loaded more heavily, and when more power was required to prevent the airplane from sinking like a brick. This frozen algorithm in my mind took away my ability to be dynamic and make adjustments to different conditions on the final approach. What I learned is that the basic landing equation involves a stable final approach with respect to both glideslope and airspeed. Although there are other schools of thought, the main controls are the throttle to control the glideslope and pitch to control the airspeed—open the throttle to arrest the sink rate, and vice versa; increase the pitch to slow down and decrease the pitch to speed up. Flaps help in slowing down as well. Using excessive power would cause a shallower-than-normal glideslope. If excessive power is corrected late in the game, it may require a forward slip to hasten the rate of descent, or a go-around will be required. A higher airspeed would mean spending more time in the flare, which can be a problem if the runway is short or the airplane touches down farther down the runway. If the pitch is corrected late in the game, it may result in a bounced landing or overshooting the runway. During the flare, if the airplane is sinking quickly, adding a pinch of power helps to provide a gradual sink and a soft landing. Landing is all a matter of positioning the airplane at the right place, at the right time, at the right airspeed.

LESSONS LEARNED
A heavily loaded airplane flies different than one that's lightly loaded. Sometimes a little bit of throttle in the flare can help smooth the landing. Get thoroughly comfortable flying an airplane before taking passengers.

ALEX WILLIAMSON

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Flight Training - September 2011

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