Ed, If you come down final too fast and too steep, then execute an incomplete flare, you can touch the nose wheel first in any tricycle gear airplane. (A similar event can occur in a tail dragger but that's another story). Subsequently, as the nose wheel "bounces" up, the mains contact the runway and the aircraft becomes airborne. The pilot instinctively lowers the nose, but overcorrects, then adds back pressure just before the subsequent nose wheel contact resulting in second, bigger bounce. A sort of harmonic occurs as the cycle repeats itself and each bounce gets more severe. That's where the "JC" part comes in, as you will see. You wondered what plane I had seen this situation in. 1961 - T-33 during a practice simulated flameout landing, I came in too steep (hey, idle power in a jet is a very steep approach) flared late and the nose wheel touched first and we bounced. I tried to counteract the bounce with the flight controls instead of going around immediately. Finally came to my senses after the second more severe bounce and added power for a go around. Got about two more bounces even after I had neutralized the flight controls and applied power for the go around. 1966 - C-130 returning to Saigon early morning after flying missions up country all night. I was very tired. Tower announced the field was under attack and they were going off the air. I was on final, continued the approach (low fuel) and flared late. Caught the nose wheel first, bounced, neutralized the controls got another milder bounce or two and full stopped. 1978 - T-38. My student flared a little late, caught the nose wheel first, We bounced, I took control, lit both burners and blasted our pink little rear ends out of there using the very high thrust to weight ratio available. 1992 - Lear 35. Two of us were taking our type rides over at Ft. Lauderdale, FL. The other pilot was flying and landed a little hot and steep on a touch and go. The nose contacted the runway first and the plane bounced into the air. The pilot tried to counteract the bounce with flight control inputs and a really severe bounce occurred followed by the pilot screaming "Oh Jesus, Oh Jesus" superimposed by the voice of the check airman screaming "I've got it, I've got it" and me hanging on for dear life in the jump seat. Check airman finally got control, immediately neutralized the controls and advised tower we would be full stop. Tower responded, "I thought so". We came within inches of catching a tip tank and rolling the airplane into a ball. Note that these pilot induced oscillations occurred in some very different types of aircraft. My point is to all of you, if you get in to one of these things, don't fight it and don't try to overanalyze it at the time it occurs. Just neutralize the controls and go around immediately. Please consider this as bacon-saving advice. Bart In a message dated 8/19/2010 7:47:35 P.M. Eastern Daylight Time, [email protected] writes:
Bart, please tell me how you think we'll get the nose gear impact, nose bounce to a high angle of attack, aircraft bounce due to lift from that high angle of attack in our Coupes? (I'll certainly agree - if you manage to get in that situation, Pilot Induced Oscillation IS a serious risk and danger. I do, still, think it's unlikely in Coupes. What planes have you seen this situation? How can we quantify this better? Any ideas?
