I have enjoyed reading the comments made here, very helpful and interesting. It got me thinking more about the issue, I have summarised some views against a summary of the main points made in other comments.
Summary of main points so far: -
1) stop display flying
A valid and logical option for the defence ministries (who fund the purchase of the assets) and the armed forces (who have just lost two very precious assets, the pilot and fighter while entertaining kids eating ice cream on the beach).
Public air displays generate a great deal of public interest and support for the armed forces and its hard to put a value on that. Public support could translate into political support, e.g. politicians will be more wary of how they treat armed forces if they are popoular in the mind of the public. A future prime minister may come from one of those kids watching air displays.
Regardless of the merits I dont ever see display flying being stopped. If Ramstein & Shoreham didnt stop them probably nothing will.
I have not seen many displays in the flesh, but those I did gave a spectacular and deep impact. They grab the attention of nearly every person from every walk of life.
2) automatic systems can cause crashes, dangerous to rely on them too much
The Mulhouse crash in 1988 of the new fly by wire A320 that flew into tree's on its first public demonstration was not due to system failure according to the recent articles by an aviation journalist last month. These articles are below and it is well worth also reading the comments made. It was aircrew error and misunderstanding of how the fly-by-wire worked that led to aircrew blaming the system.
* I am on less than 10 post so I cannot include web adresses; look on the website 'fearoflanding' (.com) and search for the articles:
Thirty Years Since Air France Flight 296
Too Slow, Too Low and Obstacles Ahead: Air France flight 296
Regardless of the cause, this airliner crash was 30 years ago when fly-by-wire was new on airliners but was already flying on fast jets.
I take the point that automatic flight systems can fail. However with careful design and development they are incredibly reliable and capable systems.
Typhoon proves this point, it could not fly without them; it is unstable and relies on the flight control computers to keep control of it in every speck of its huge flight envelope and in every conceivable configuration. By comparison, ground avoidance is a far easier requirement to meet for automatic flight systems.
3) Its too expensive to develop a system
For the flight control designers to add a display ground avoidance function to their already comprehensive task of designing a system to fully control the aircraft in all configurations in all parts of the flight envelope, is easily possible. Typhoon is already half way there; it has an automatic recovery function that when selected automatically recovers the aircraft to a safe attitude.
A small dedicated team could have designed a ground avoidance function (at least offering some protection if not total protection), grabbing information from the main flight controls team already in place. A similar sized team could test and develop the software using simulators topping off with aircraft tests piggy backed onto the existing flight test programme. Lets say that would cost £10million.
This system could have been fitted to all aircraft, so that is sharing £10million between the four countries making the Typhoon. You could also sell the ground avoidance system to export customers and for use on other aircraft.
Cost of one Typhoon is about £75million (£110million by some estimates)
Cost of Italian test pilot killed is well over £4million
- £4million to train and get to squadron
- over one thousand hours of fast jet flying @£15k per hour roughly?
- Graduation from test pilot school?
TOTAL COST = well in excess of £79million, maybe as high as £140million.
Saving that one Typhoon from crashing would have made a ground avoidance system worth it many times over. Even a limited ground avoidance system would have been able to see that crash coming and at least warn the pilot if not initiate recovery. A ground avoidance system could possibly prevent future Typhoon losses/fatalities, especially if utilised not just in air displays. The link below lists Typhoon crashes to date and possibly had there been at least some warning of the approaching unavoidable crash more pilots may have ejected and been saved?
* I am on less than 10 post so I cannot include web addresses; visit 'fighterjetsworld' (.com) and earch for web page:
Crash Videos of Eurofighter Typhoon List of All Eurofighter Typhoon Crash So far
4) its not feasible / aircraft cannot know what the intended manoeuvre is and so the system cannot work
I think that the Tornado IDS had a terrain following system that was in effect a ground avoidance system, consisting of a ski slope curve projected ahead of the aircraft. When terrain broke through the ski slope the aircraft pulled up to clear the ski slope from the terrain.
Maybe a system using some form of 3D ski slope volume constructed around the aircraft, representing the max manoeuvre ability of the aircraft from its current position, could determine if the aircraft was approaching a position from which it is not possible to avoid the ground with any manoeuvre. This does not require to know the intended manoeuvres but only the aircraft position, aircraft max manoeuvre capability and where the ground is.
5) It would make the display boring (i.e. system flying display)
If the display was flown correctly the system would never kick-in. There would be no observable difference in the display, it would still be a pilot flying the aircraft to its liimits. Even if a mistake was made the system would only kick-in to avoid a crash condition, not to catch non-dangerous mistakes.
6) Fast jets are soon to be replaced by unmanned aircraft, not worth investing now in an avoidance system
If those unmanned aircraft are going to fly displays, why not fit a ground avoidance system?
If it crashes that is still a very valuable asset lost. At some point there will be UAV's doing combat at low level. Such an UAV will benefit from a ground avoidance system.
7) No need for safety systems as long as pilots fly right i.e. dont make mistakes
History shows that pilots do rarely make mistakes despite them being highly trained and highly professional. Rare as they are, when they happen they cost highly prized assets in pilot and machinery.
8) ground based observation is not infallible because the observer will not know precisely what the pilot is planning to do next.
Unless the display went exactly to plan I cant see a way around that problem. Coupled with the time lag between seeing a problem and relaying it to the display pilot, probably no practical advantage could be had.
A previous comment mentioned a two seat F-15 air display with a second pilot acting as an additional safety mechanism in the aircraft. If that was effective should displays use twin seat aircraft? Doesnt have the same thrill factor for onlookers, though.
I guess that some displays are cutting things so fine that even a second pilot would not have time to take control and recover; possibly end up with two dead pilots instead of one.
9) such a system could result in the aircraft being placed on a vector towards the crowd, i.e. could jeopardise crowd safety
That is a fundamental problem but not impossible to solve. The system could be programmed with the crowd locations and permissable corridors to operate in.
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It is technically possible to make a ground avoidance system and it is financially viable to make such a system. The system may have limits but if it saves one pilot/aircraft it will pay for itself.
Such a system would be useful for truly autonomous UAVs, especially in combat roles.
I wonder if the reason it hasnt been done is that it has never been put in the aircraft requirements given to industry?