Review

In general, RAF policy towards those unable to attend a board of inquiry by reason of their own deaths, is supposed to be charitable. Destouches's cynical maxim that "les absents ont toujours tort" may hold good in civvy street but professional decorum in the RAF insists that "les absents" should be given an even break. The principle is even enshrined in official regulations: "Only in cases where there is absolutely no doubt whatsoever should deceased aircrews be found negligent." Despite this unequivocal guideline, and despite the fact that there is no evidence whatsoever, Rick Cook and Jonathan Tapper were posthumously found guilty of "gross negligence" by the RAF, after the fatal crash of a Chinook helicopter which killed 25 top British Intelligence personnel.

Given the nature of the passengers and the continuing absence of explanation, this accident would seem to be peerless compost for conspiracy theories and paranoid surmise. Indeed, as the baleful opening sequence unwound, that was what you braced yourself for - a tale of spooks and skulduggery. But Cutting Edge's film (C4) was commendably sober in its method, concerned only to establish that an injustice had been perpetrated. Even its use of John Nichol, the Gulf War pilot, as chief investigator turned out to be useful, rather than a mere garnish of Top Gun celebrity.

The case against the RAF was relatively simple - that despite doubts about the airworthiness of the Chinook Mark II helicopter (a reconditioned version of a long-serving aircraft), it had allowed many important eggs to be put into one unreliable basket. The dead pilots themselves had expressed anxiety about flying the new helicopter and test pilots at Boscombe Down had twice grounded the Mark II because of unexplained failures in some systems. Five days before the crash, the same aircraft had demonstrated control system problems, including "undemanded engine shut down" and "spurious engine fail captions". The section of the flight manual dedicated to limitations - that is, the safe parameters within which the aircraft must be flown - consisted of a single white sheet adorned with the words "To be issued". In short, the RAF had a very powerful motive for pinning the blame on two pilots who could no longer defend themselves - cutting off responsibility for the disaster before it rose too high up the ranks and also preventing what would presumably be an awkward and expensive grounding of other Mark II aircraft.

The MoD refused to take part in the programme, or to allow Nichol access to their crash investigator, a wearily familiar stonewalling strategy. They must surely learn some day that such taciturn secrecy only sends off a powerfully arousing scent of cover-up, both to interested journalists and grieving relatives. Incensed by the brutality of the verdict, both fathers have made it their business to fight it, despite the fact that their backgrounds make them unlikely opponents of traditional authority. "As Mandy Rice-Davies said `They would, wouldn't they'," said Jonathan Tapper's father after being presented with one of the MoD's evasive statements. As that sardonic anti-establishment rallying cry issued from the mouth of a city banker who specialised in defence, you marvelled again at the MoD's ability to transform its natural allies into the bitterest of enemies. If they could only manage the trick the other way round, we wouldn't have to worry at all.

Adam Hart-Davis continues to zoom about the country in Local Heroes (BBC2), like a boiled-sweet on a bicycle. Visiting hallowed sites of ingenuity, he exhumes the reputations of Britain's inventors, his subjects ranging from the eccentric (the pioneer of the windscreen wiper) to the absolutely pivotal (Joseph Swan, inventor of the light bulb). The presenter is rather like one of the scrap-box models with which he demonstrates the principles involved - a harnessing of natural energy which vents steam and hot air in a slightly unpredictable manner. Very enjoyable though, and I now know how to light my house with empty pop bottles, some copper wire and a dab of liquid nitrogen.