I feel sorry for Tom Ridge, head of the US department of homeland security. Following those decisions to ground or delay British Airways Flight 223 - one of the late-afternoon flights from Heathrow to Dulles, and one that I have taken dozens of times - he has come in for waves of the kind of sceptical disdain that Britons tend to reserve for Americans when they feel superior. I know Ridge well enough, however, to believe that he must have found the decisions not to allow the British and other international flights to head for US airspace especially agonising. Not long ago I asked him how he felt when Dubbya first invited him to become head of a monumental new government bureaucracy - in charge of 22 hitherto independent government departments, 180,000 employees and a working budget of $38bn. "Aargh," he replied immediately, showing a levity he dare not now allow to be seen in public.
Before the 11 September atrocities, he told me, he had been planning to retire as governor of Pennsylvania and go into private law practice to make some money. Then came the fateful call just days after 11 September - and he could not say no. It was (and remains) just about the most daunting job in the world: one in which you are damned if you do and damned if you don't. Or, as he put it in the Washington policy-wonkese that comes naturally to him, he is continually on the receiving end of "post-incident reflection" - the reviewing of decisions in the light of what transpired following those decisions. It is possible that the department has already foiled horrible terrorist plots, but we are unlikely ever to know for certain either way. Ridge can easily be blamed if there is another security lapse, but is unlikely ever to be thanked for creating conditions that prevent more terrorist attacks than would otherwise have happened.
And if there is one thread running through private conversations with both senior American and British intelligence officials, it is the inevitability of another terrorist atrocity being perpetrated on either country. There is only so much that Ridge and his British counterparts (David Blunkett and Eliza Manningham-Buller, director general of MI5) can do. Ridge told me he was working closely with both over biometrics - fingerprinting being the most simple example and iris-scanning the most sophisticated - and, indeed, compulsory fingerprinting for visitors to the US was introduced on 5 January.
Or, at least, that was what the news reports said. Fingerprinting and photographing were indeed introduced at 115 airports and 14 seaports here, with Ridge saying: "It is part of a comprehensive programme to ensure that our borders remain open to visitors but closed to terrorists." But because visitors from 28, mainly European, countries are exempt, the system would not have caught Richard Reid, the British shoe bomber who all but blew up an American Airlines flight from Paris two years ago, or David Hicks, an alleged al-Qaeda terrorist from Australia (another exempt country) currently held at Camp Delta in Guantanamo Bay.
Indeed, when it comes to the fingerprinting and photographing and practically every other anti-terrorist measure his department has adopted, Ridge knows full well that the system is still riddled with holes. Five hundred million people visit the US every year, and only 24 million are falling under the impressive-sounding new fingerprinting scheme. Visitors entering the US at hundreds of land crossings from Mexico or Canada, for example, are currently not included - a glaring gap for any aspiring terrorist to exploit. Then there is the problem of system overload: simply too much information coming in to be properly processed by the Ridge's department. Ridge told me that more than seven million shipping containers enter the United States every day; he added that the authorities were now receiving more manifests as to what the containers have inside them. However, this is hardly useful if they are not opened and yet contain explosives or WMDs and have fake manifests.
Ridge meanwhile acknowledges that the fingerprinting programme is "the first significant step in a series"; but both this and the checking of incoming containers show that his job is virtually impossible. That is why, if a name on a flight passenger manifest matched that of one on a computer list of suspected terrorists, I would have grounded those BA223 flights myself.
"Can you imagine?" Ridge asked me rhetorically about the fallout if there was to be another aviation or shipping atrocity when prior information had been ignored, the authorities simply keeping their fingers crossed. Ridge and his department would be squarely blamed if possibly relevant information, however nebulous, was ignored and flights allowed to leave and mass fatalities resulted - an almost intolerable burden on one man.
Ridge's job is made still more difficult by the way it was structured by Dubbya's White House. His department consists of just 32 buildings at an old naval base in north-west Washington, and the amalgamation of the 22 government departments is theoretical rather than actual; in most ways, it is government as before. For example, the old Immigration and Naturalisation Service (which has become extremely important) is now known as the Bureau of Citizenship and Immigration Services under the Homeland Security banner.
But there is a still more intrinsic fault line in the structure: Ridge's departments do not include the two most vital government bodies combating terrorism, the CIA and the FBI. Both fought fiercely for their independence when Boy George's team was setting up the Homeland Security, and each remains independent; together with John Ashcroft's department of justice, which is in charge of al-Qaeda and other suspected prisoners. The FBI and CIA are supposed to hand over all relevant information to Ridge - he receives a briefing from the CIA every morning before going in to see Dubbya at around 8am - but from their inception, each has had a notorious habit of playing its cards close to its chest. In a city where information is power, the CIA and FBI are, in fact, preternaturally inclined to hold on to their own intelligence and secrets.
The challenge for Ridge, therefore, is to manoeuvre his department into a position to absorb all relevant data from the CIA, FBI and department of justice while simultaneously avoiding information overload and retaining an ability to tell the wood from the trees.
Juggling all the balls in the air, knowing that he may not have proper access to intelligence even from within his own country, makes Tom Ridge's job hugely daunting. Which is why I think he needs all our sympathy. The naysayers may decry the decisions he makes - particularly when they involve grounding British airlines - but who would willingly be in his position?