What is the correct procedure in case of vertical stabilizer failure in cruise?
Am I correct in guessing that one should descend to a lower altitude and decrease speed?
Aviation Stack Exchange is a question and answer site for aircraft pilots, mechanics, and enthusiasts. It only takes a minute to sign up.
Sign up to join this communityWhat is the correct procedure in case of vertical stabilizer failure in cruise?
Am I correct in guessing that one should descend to a lower altitude and decrease speed?
There is no procedure, generally a vertical stabilizer failure makes an airplane uncontrollable, meaning everyone dies. There have been examples where vertical stabilizers failed and people survived, see this question for details. A pilot local to me cut 2/3 of his vertical stabilizer on high tension power wires while scud running and still landed safely.
When there's any control surface failure pilots will have to learn how to fly the airplane and control it using whatever means possible. Differential thrust and speed brakes have been used to control lateral movement (yaw), trim can be used if controls are seized, etc.
Reducing speed may not be a good idea, or at least not all at once, if the vertical stabilizer fails airflow over whatever stump remains may be the only think keeping it straight. If the control is stuck then reducing speed would make sense, it all depends on the nature of the failure. Descending is absolutely a requirement, you have to land somewhere after all, but unless you've depressurized there's no need to rush it, you'd want to work the problem and find out what the new parameters are, then gingerly work your way down.
Am I correct in guessing that one should descend to a lower altitude and decrease speed?
Yes, if you fly an aircraft with a backward swept wing. Otherways, losing the fin will be impossible to compensate.
This answer explains how a backward swept wing will aid in directional stability, and this help increases with angle of attack. Therefore, flying slow is the most important step in order to restore directional stability. Flying low increases aerodynamic damping, so low and slow is the best choice in this case.
@Carlo mentions B-52H 61-023 which lost most of its vertical on January 10, 1964. This aircraft survived, but a number of them who suffered the same fate crashed. There were several factors which helped:
What is the correct abnormal procedure in case of vertical stabilizer failure in cruise?
My advice: Don't count on being as lucky as B-52H 61-023, but bail out as long as you can!
Depends on the aircraft. Generally structural failure results in departure from controlled flight, though there are a few exceptions such as this USAF B-52H which lost its vertical fin over Colorado on Jan 10, 1964.
Oddly enough, the loss of a vertical fin is probably the least riskiest form of structural failure. An airplane can still maintain approximate directional control from the longitudinal center of pressure from the tailboom of the airplane well behind the center of mass, provided all other systems remain functional. The airplane can still be turned using aileron input, though slipping and skidding from adverse yaw and other factors are going to be much more pronounced demanding greater care in handling at lower speeds. Multiengine aircraft will most likely depart from controlled flight here in the event of an engine failure. Again the severity of the loss of control here will depend on the amount of structure lost and it’s effect on directional control.