one minute before impact, the crew of flight 427 is alerted to another airplane that will be passing below them. they re looking for the airplane. first officer acquires it visually and tells the captain, yes, i see the jet stream. and then they encounter the wake turbulence of a delta airlines 727 and not an uncommon event at all. the airplane rocks around and moves. and from that moment of encountering the wake, something happened. they couldn t stop the roll in the airplane. and this was very difficult to listen to as a pilot because i could hear them struggling for control of the airplane and every second that ticked by they were losing that battle. as seen in this ntsb video, investigators set up a test flight that would examine the possibility that the u.s. air pilots were startled by the wake of a nearby 727 airplane causing them to lose control. what we found was you could take the airplane, let go of the controls and the airplane would come out of the wake and regain its
can then deflect the rudder in the opposite direction. if you jam the secondary valve just slightly off neutral, you could cause the valves to basically misalign and import hydraulic fluid in the wrong direction so the rudder reversed operation. this would be like driving your car and you turn to the left and the car goes right. you ll never figure this out before the car goes off the road. investigators had found a lethal malfunction in a valve the size of a pencil capable of bringing down a boeing 737. the malfunction leaves no marks or scars, almost as if it never happened, matching exactly what investigators found in u.s. air 427. all of a sudden you put the reversal scenario in and it all started coming together that all these parts now fit. the big puzzle we ve had the edges and everything else, now the center pieces are all locking in. when flight 427 s crew encountered the wake turbulence of a passing airplane, they press down on the rudder pedals to counter the wake an
tip of the leading airplane. and if the trailing airplane intercepts that cone, you will feel choppiness. typically, the encounters are very brief, but you can hit them multiple times. and that is exactly what happens with flight 587. there are two wake encounters. although invisible to the human eye, they are displayed here in our animation. the first wake causes the plane to roll to the left, and the co-pilot quickly puts it back on course. but then, 15 seconds later, the plane is caught in a second wake. when this pilot got into the wake turbulence, the airplane started to roll. he put in flight control corrections that he thought was necessary to get the airplane back to a wings-level state. but instead of leveling out, the plane moves violently on all three axes of flight, left and right rolls, side to side motion and then up and down. then the unthinkable happens. the tail snaps off. the plane banks left and plummets into a residential neighborhood in bal harbour,
overemphasized the use of the rudder inputs. going a step further, john cox says the rudder should never be used in wake turbulence. the best response would have been to let the airplane s natural stability work through it. the airplanes are naturally very stable. and so put control input into bring the airplanes back towards wings-level and let it fly out and it will settle right down. american airlines told nbc news that it continues to be disappointed with the ntsb findings and believes that the design and rudder sensitivity were at fault. a decade after the crash, the report stands as written. but in august 2010, the ntsb started reexamining similar incidents and urged agencies to take a closer look at the rudder design. pilots now understand, you don t have to move the rudder that much, as far as the pedals are concerned, to create a large
everybody s role. the co-pilot is flying the plane and is about five miles behind a 747 on its way to japan. we re climbing to 5,000. since the airbus is climbing faster than the plane in front of it, flight 587 quickly climbs into the 747 s wake, causing the american airlines plane to experience turbulence. this, in itself, is not uncommon. airplane wakes are common to the wakes made by boats or ships. it is a displacement as the vehicle passes through this fluid, in one case water, in one case air. this faa simulation illustrates a different jet flying into wake turbulence. the wing tips from the lead plane create what is known as a wake vortex. you can think of it as a very large cone coming back off the