Originally Posted by
airsound
Dr Stephen Jarvis. He adduced seven, eight, or possibly even twelve, piloting errors in the 23 seconds leading up to the aircraft’s arrival at the apex of the accident manoeuvre (the bent loop). They included:
- Unexplained power reduction.
- Continuing the turn beyond the appropriate inbound track.
- Failure to notice low speed.
- Pitch oscillations.
- Incorrect roll in the vertical.
- After, the apex, the failure to eject. That would have been a rule-based action, from his training.
I would like to postulate reasons for three of these errors listed above:
- Continuing the turn beyond the appropriate inbound track. We do not know precisely what point on the display line AH planned to point towards. From the height and distance that he was from the display line the sightline angle was very shallow and he may not have had a full perspective of the runway. Similarly, judgement of the required pull-up point is difficult and is a purely visual assessment and that is one of the biggest potential errors in flying this manoeuvre. There is a great deal of scope for all of us to make an error with judging this aspect of such a manoeuvre.
- Pitch oscillations. This reference was to immediately after rolling out of the turn prior to the pull-up when about 2 cycles of a very low amplitude pitch oscillation occurred. This is a normal open loop Hunter response, and if anyone wishes I am quite happy to give a full explanation.
- Incorrect roll in the vertical. In this manoeuvre, the required roll angle will always be different every time that you fly it due to the angle off the display line, distance from the display line and on/off crowd wind component. There are no visual cues that you can use when the roll angle required is small; you make the input with partial aileron by cadence alone and there is a great tendency to 'over-roll', especially if, during the pull-up, you realise that you have pulled up too soon and try to roll through more than the angle required for the heading change in order to displace and exit on the display line.
All of the above potential error mechanisms may occur without cognitive impairment. With respect to a rule based ejection option, this would have included rolling wings level then pulling to a level or slightly nose high pitch attitude which is the same as an escape manoeuvre. However, no competent display pilot would ever consider that ejection should be an option at the apex of a loop when the gate height has not been achieved and, therefore, I contend that ejection would never be a rule-based action in this situation.
There have been many comments on here regarding hours on type, currency and flying multiple types. A few points to ponder:
- Military display pilots, except for those involved with dedicated display teams such as RAFAT or BBMF, typically fly only one or occasionally two display seasons. Therefore, they have low overall display experience which is mitigated by flying rigidly defined sequences with a great deal of practise and stringent currency requirements. These mitigations are not necessary to the same extent for pilots who have decades of display experience on multiple types.
- Flying and displaying multiple types can be done safely but does require the pilot to have a robust philosophy and protocol for how they will refresh their competence. Under MAA (and precursor organisation) regulation pilots have maintained type currency on up to 9 widely different types of aircraft, including displaying some of them. What is interesting is that significantly different types are not a problem; it is types that are similar where cognitive errors tend to be made. The worst aspect is flying different airframes of a given type with some ASIs in KIAS and some in mph!
- An experienced display pilot can start displaying safely a new type on which he has few hours and with little practise or recency if the display sequence and the manoeuvres are appropriate ie. no pulling through the down vertical in looping manoeuvres, all rolls on a climbing line, no maximum AOA turns. I am happy to give examples.
- All of the above require two factors. First, a pilot with the requisite experience, ability and attitude. Please note that I am making no comment here about Shoreham but I am talking generically. Not all pilots and not all display pilots do have the required attributes, but those who do should not be prevented from flying displays which they are capable of doing safely just because other pilots cannot. Secondly, mentoring/supervision/training. Some pilots need more than others but these are essential aspects that are not always to the required standard.
Again, I will not make any comments about Shoreham specifically but mentoring and supervision need to be considered. However, I will raise one specific aspect regarding training and that is flying escape manoeuvres. At the time of the accident CAP403 did not require pilots to ever practise or demonstrate their ability to fly escape manoeuvres and AH stated that he had not done so. It was only required to be discussed under the 'Emergencies' aspect of DA issue. Thankfully, this is now a requirement for DA issue. Allied to this, an Aircrew Manual such as that for the Hunter will never cover in detail, if at all, how to fly these manoeuvres, especially at low IAS. This has to be an essential aspect of training, even if it is just a briefing on how to do so. The Hunter has outstanding handling qualities in this respect and the AAIB flying demonstrated that an escape manoeuvre could be flown safely at 80 KIAS without any abnormal skill. Any skill based activity is ~70% confidence, and if a pilot has never been briefed or practised an escape manoeuvre in a swept wing aircraft at an IAS significantly below the 1g stall speed then they may lack the confidence to do so for real when required.