This thread has identified some interesting aspects of training and operation.
1. Does the particular simulator correctly represent a jammed control system?
2. What is the purpose of simulating a jammed control during take off; what are the training objectives of this event?
3. Has a new procedure been generated just to overcome possible simulator deficiencies?
1. The manuals indicate that a jam either in the control input or at the control surface is unlikely, but if a jam did occurred, then alternative split systems or reversion to manual will regain sufficient control. The simulation as described appears to be incorrect.
The drill for a jammed system appears to start with applying force (after checking the autopilot is disengaged – interesting see the Air NZ 777 thread). Control is achieved with control column movement; trim is used as a follow up input to relieve control force - as per normal flight.
The problem during GA appears to be due to the ‘large’ and ‘rapid’ change in trim due thrust increase.
The takeoff trim setting is usually such that the aircraft is reasonably in trim at V2 – V2+10; there should not be any change in trim due to thrust change, thus no trim input would be required until the aircraft accelerates. Any inappropriate use of trim would put the aircraft out of trim
2. As stated in an earlier post, I would expect simulator training to demonstrate a failure, practice the identification and selection of appropriate action, and then practice the subsequent flight procedures. Thus the objectives might be to present knowledge, practice assessment skills, and then practice flight and planning skills.
3. I hope that the procedure was not introduced to cure a simulator deficiency, but I have seen examples of this elsewhere.
I joined this thread on the back of earlier replies which generally agreed with the decision to discontinue the takeoff and attempt to stop within the remaining runway distance. In this context, note that the simulator may not correctly represent stopping performance, particularly on a wet runway.
Recent information now suggests that the decision was incorrect. This view, particularly the judgement of correct/incorrect is made in hindsight, but as in most accidents/incidents, the decision in the eyes of the decision maker at that time is ‘always’ correct. The decision would be based on what is seen, assessed, and understood, - as clearly explained by skyeuropecapt earlier.
It appears to me that in this aircraft there is no need to consider a jammed control as a reason not to fly when identified at and after Vr; thus removing the possibility of an overrun accident. In some aircraft types it might be assumed that a jammed control system is identifiable before V1 and thus an RTO would be justifiable, but not later as modern aircraft certification requirements provide alternative courses of action.
I too would like to understand if this simulator is correct, exactly how does the aircraft behave at rotate, how might the reported control forces be related to other flight operations (e.g. stick force equal to 20kts out of trim) and thus aid crews to better understand what to expect with such a failure?
A good thread for learning … … and thinking.
P.S. from FCTM - ‘light forward pressure’ becomes ‘forward pressure’ in the Adverse Runway Conditions section. Perhaps it’s all relative; not necessarily new procedures, just different interpretations of manuals – like different assessments of a situation.
Errors in Aviation Decision Making.