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Mr. Hoon: I am sorry to interrupt the right hon. Gentleman again, but he has not answered my earlier question. He seems to be suggesting that the Government should simply accept the report of the House of Lords Committee without further investigation. Is that what he is saying?

David Davis: I did answer the Secretary of State's question once, but he will have to wait until the end of

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my speech to hear what I have to say about the simulator. I have some questions for him, which I hope that he will answer in his own speech.

I fear that the Government will maintain their pattern of behaviour in ignoring the findings of independent, expert and reputable bodies that have examined the accident in detail. They say that there is "no new evidence". That fails to take on board the fact that the House of Lords has shown that the original verdict was based on fallacious or non-existent evidence.

Mr. David Rendel (Newbury): It has already become clear that the original decision of the air board was changed by the air marshals when they made their final decision, without their having any different evidence to consider. If it is possible for a decision to be changed on the basis of judgment as to where the blame lay, with no new evidence, why is it not possible for the Government to change a decision on the basis of "no new evidence"? I agree with the right hon. Gentleman that there is probably plenty of new evidence, but even if there were not there would be no reason for the Government to stick to their decision.

David Davis: The hon. Gentleman is right. He was also a member of the Public Accounts Committee at the time of the discussion, so he is familiar with the Government's problem of "no new evidence". I shall say more about that later.

Let us consider the course of events during those fateful days in 1994. On the day of the last flight of Chinook ZD 576, after obtaining weather reports Flight Lieutenant Tapper decided that the flight to Inverness would be a low-level sortie flying under visual flight rules, or VFR, and intimated that he was not intending to fly under instrument flight rules—IFR. Indeed, flying under IFR in the vicinity of the mountains to the east of Ballachulish and Fort William would not have been permitted because of icing restrictions. Flight Lieutenant Tapper therefore selected a route that included flying towards the Mull of Kintyre lighthouse, which was programmed into the Chinook's computerised navigation system as way point A, and from there to Corran on Loch Linnhe, programmed as way point B. According to the SuperTANS computer, the Chinook was a mile from the lighthouse when the crew selected the next way point.

The original air marshals' criticism of the two pilots was based on the assertion that they had voluntarily flown over the Mull of Kintyre at too low a rate of climb in instrument conditions. But why would an experienced helicopter crew, immediately after selecting a pre-programmed visual way point, suddenly agree not to turn on to it, switch to instrument flight rules, which they had ruled out at the pre-flight briefing, and fly straight on to cloud-covered high ground which it knew to be there? Special forces helicopter crews exercised regularly in that area and were extremely familiar with the landscape and the weather conditions associated with it.

When the matter was debated in Westminster Hall, the Under-Secretary of State for Defence said:

"they flew on, contrary to instrument and visual flight rules. The evidence is that they were already too close to the cloud-covered mass of the mull and were travelling too low and too fast."—[Official Report, Westminster Hall, 27 June 2000; Vol. 352, c. 174WH.]

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That is the basis of part of the accusation for gross negligence, but it does not add up. On what evidence was the ZD 576 "too low" at way point change? The only concrete data were an eyewitness account from a yachtsman, Mr. Mark Holbrook, who saw the helicopter at the height of between 200 and 400 ft about two miles from the mull. The helicopter was clear of cloud and in sunlight. That is consistent with the crew's visual flight rules flight plan, which was seen and described as being "thorough and professional" by the board of inquiry. There is no case for the aircraft being too low.

Mr. John Wilkinson (Ruislip-Northwood): May I refer my right hon. Friend to the logbook entry of the Sea King crew members who went to the scene of the accident? They made it absolutely clear that the weather around the lighthouse was nowhere near visual flight rules. In fact, they had to grope their way in at 100 ft with radar assistance, and they spoke of sucker holes, which is just the sort of thing to which the yachtsman referred. The cloud conditions change very rapidly in that kind of terrain. One may get a fleeting glimpse of an aeroplane; it does not mean that it is in visual flight rules.

David Davis: I recognise my hon. and gallant Friend's experience in this area. The Sea King went after the accident. It is well known that the weather changes in that area, a point well understood by the special forces crew that flew there, but I will come back to that point.

On what evidence was ZD 576 "too fast" at the way point change?

Mr. Menzies Campbell (North-East Fife): I do not know whether the right hon. Gentleman intends to leave consideration of Mr. Holbrook's evidence, but if he has carefully examined the report, as I am sure he has, he will know that at page 19, paragraph 67, the conclusion of the Select Committee of the House of Lords was to say:

"We had no hesitation in accepting him as a reliable and convincing witness."

David Davis: The right hon. and learned Gentleman is exactly right. One of the problems was that the Royal Air Force appeared to write off Mr. Holbrook's evidence early on and to view him as a fallible witness, for reasons perhaps touched on by my hon. and gallant Friend the Member for Ruislip-Northwood (Mr. Wilkinson).

The air marshals tried to tell the House of Lords Committee that the Chinook ZD 576 was going so fast that it would not have been able to turn in time to avoid the cliffs, but that was based on false assumptions. First, it assumed that the aircraft was travelling at the ground speed of 174 knots used by the Boeing simulation. There is no basis for that assumption.

Nobody knows the speed at the way point change. The tail wind was about 20 knots, and the Chinook normally cruises at 130 knots. According to the inquiry, ZD 576 crashed at 150 knots ground speed but that does not tell us the speed at the way point. Mr. Holbrook, the yachtsman, estimated the speed of the Chinook when he saw it at about "60-80 knots".

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The Lords Committee also concluded, based both on Mr. Holbrook's statement and expert witnesses,

"that the crew had probably seen the land mass at or before the time the way point was changed."

So the witnesses' evidence points to the Chinook flying in visual flight conditions, at the right height, at a lowish speed. The Lords Committee criticised the board of inquiry for not paying more attention to the yachtsman's evidence.

Mr. Hoon: Does the right hon. Gentleman accept that at the way point change the aircraft was functioning perfectly properly?

David Davis: It is probable but the problem is that we are dealing here with requirements of absolute proof. However, even if the aircraft behaved perfectly properly at the way point change, it is entirely possible that, immediately after the way point change, that ceased to be the case. Flight jams are well known to occur. Evidence given by the squadron test pilot of the Chinook suggests that flight jams occur very often on change of direction. That would have occurred immediately after, or within seconds of, a way point change.

Mr. Wilkinson: My right hon. Friend will recall that the heading change was something in the order of 13 deg, a minuscule injection of bank and heading change. If there had been something wrong with the aeroplane as it went across the Irish sea, the crew would have aborted the sortie, changed the flight profile or issued a pan call—an emergency call. It would have been perfectly plain. They did nothing of the kind, so the assumption must be that they pressed on in the knowledge that all systems were working perfectly. They had good time to put a call into military air traffic Scottish region.

David Davis: I am afraid that the use by my hon. and gallant Friend of the word "assumption" rather blows the case. We cannot make assumptions on this. The level of proof required is no assumptions. Two witnesses who spoke to the House of Lords Committee—witness A, a special forces pilot who could not be identified, one of the most decorated pilots around today and certainly very high on experience of Chinooks, and Squadron Leader Burke, who was the squadron test pilot on the aircraft—both recognised intermittent faults that were brought on in erratic, unpredictable ways, and a small change of direction could well make that change. I will come back to the point later, but the simple fact is that they both thought that the most likely outcome was a control jam after the way point.

The Lords Committee found that there was no evidence to back up the data used to estimate the Chinook's height, speed, position and course at

"any time prior to impact",

so the whole approach of the air marshals was based on a lot of assumptions.

The MOD's assumption that the way point change was made when the aircraft was some 600 m from the cliff is based on information retrieved from the Chinook's computerised tactical area navigation system, also known as TANS or SuperTANS. That system was heavily damaged in the crash.

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The RAF used TANS as the basis for its reconstruction of the final seconds of the flight claiming that the data used were

"facts based on clear evidence".

One of the air marshals, Sir John Day, used this information to

"build up a rudimentary accident data type recorder picture of the last 20 seconds of flight".

The Lords Committee dismissed these claims as "hypotheses and assumptions". Further, according to the manufacturer, the computer was never designed to give historical data. In addition to that, it had hit a mountain at 147 knots, or l70 mph, and then burned. Who would believe any information garnered from that computer to be 100 per cent. accurate? Even given that, that computer system was well known to be subject to errors.

There is an ironic example. On 13 July 1995, a Chinook mark 2, the same sort of Chinook, was tasked to perform an overflight of Flight Lieutenant Jonathan Tapper's memorial. Crew members were in visual contact with the ground and they knew when they were precisely over the memorial. The TANS on that aircraft indicated that the aircraft was 2 nautical miles away from the memorial—the system "believed" it was some 2 nautical miles away from the aircraft's actual position, so the system is certainly fallible. Again, I remind colleagues of the level of proof required.

The House of Lords Committee therefore threw out the "wrong place, wrong speed, wrong height" argument of the air marshals. That leaves the problem of how the Chinook came to crash into the mull. Was there a technical fault that made the aircraft difficult or impossible to control, which was implicit in the Secretary of State's questions to me earlier?

Under the rules of "absolutely no doubt whatsoever", the MOD is required to eliminate any such possibility. Sir William Wratten, the senior air marshal, has stated that the RAF board of inquiry found a "total absence" of any technical problem that could have caused the crash. In a crash of this destructiveness, it is entirely possible that all evidence of a control problem could be destroyed. Actually, there is evidence pointing to at least three possibilities: an engine control problem, a control jam and a hydraulic system problem. Furthermore, the investigating board did not rule out a distracting technical fault.

In particular, the board noted that the Chinook had been experiencing engine control system—known as FADEC—malfunctions, including "undemanded run-ups". That technical phrase basically means sudden surges of power that could destabilise the helicopter. The board noted also that an

"unforeseen technical malfunction of the type being experienced on the Chinook . . . remained a possibility that could not be discounted."

Again we must remember the requirement for the level of evidence.

It has also emerged that, at the time of the crash, the MOD was suing both Boeing and Textron Lycoming—the manufacturers of the Chinook and its engines, respectively—because of faulty test procedures and a design fault in the aircraft's FADEC software. Malcolm Rifkind has said that if he had known this and the other technical problems at the time of the investigation, he would not have supported the verdict of the air marshals. He was the Secretary of State at the time.

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The RAF's board of inquiry did not properly consider either of these facts. Indeed, it neglected to take evidence from Squadron Leader Bob Burke, the vastly experienced Chinook test pilot, and Malcolm Perks, the technical expert who had spent many years working in the field of FADEC, often for the MOD. Both men gave evidence to the Lords inquiry about the FADEC system and the possible flight control problems that it could cause.

After the accident, the investigators found that a number of components in the Chinook's hydraulic flight control systems had become detached. The air accidents investigation branch stated that the possibility that these components

"had detached prior to the accident could not be dismissed."

In fact, three weeks before the accident, this same Chinook suffered an undemanded flight control movement caused by detachment of one of the same set of components. This and its dire flight safety implications were noted in an engineering report made by the helicopter's ground crew.

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