The tragic events of 11 September 2001 took more than 3,000 lives and led to a spiralling international crisis. The effect this has had on the business world has compounded an already epic disaster.
Of all the sectors affected by the attacks, global tourism stood to suffer more than most. The familiar and terrible footage of passenger jets being used in such a destructive way was shocking enough, without the extra problem it presented to the tourism sector rebuilding public confidence in foreign travel.
For the UK's beleaguered tourism industry, the past 18 months has been a period to forget. During 2001, there was a £1.5bn decline in revenues from overseas tourists, with 11 September following on from the impact of foot-and-mouth. And this week, British Airways was facing relegation from the FTSE 100 index for the first time.
Industry bodies are divided on the exact extent of the woe. The British Tourist Authority's upbeat estimate for 2002 sees a rise in foreign visitor numbers of around six per cent over 2001. But the British Incoming Tour Operators Association (BITOA) forecasts that tourist numbers in 2002 will be around four per cent down on last year.
Both agree that a significant recovery will not occur until 2004 at the earliest. Understandably, North American tourists - around 20 per cent of all visitors to the UK - are particularly reluctant to fly.
And it was Americans, says BTA press officer Elliott Frisby, who were most doubtful about visiting the UK after foot-and-mouth.
In addition to its usual PR work - each year the BTA runs up to ten campaigns on aspects of the UK - the BTA has undertaken two major ad and PR campaigns in response to the downturn.
The first, 'UK:OK,' began in January, as a £5m attempt to overcome foot-and-mouth. This was, though, small beer relative to the subsequent 'Only in Britain. Only in 2002' campaign, a £40m public-private partnership.
More than 20 major firms contributed at least £100,000 in support of the work.
Focus group research led to the identification of four 'core values' for Britain's tourism: heritage, the countryside, sport and cities.
Activities have focused on seven key countries: the US, France, Germany, Holland, Belgium, Ireland and Canada.
BITOA chief executive Richard Tobias says the resultant, somewhat quirky campaign, which has played on Britain's perceived eccentricities was, despite some criticism at home, 'generally well received in key markets'.
The BTA's PR initiatives this summer have involved 20 black taxis, branded with the 'Only in Britain' regalia, touring Europe.
Secondly, in July, to reach the US market, Mancunian actress Jane Leeves - who plays Daphne in US comedy show Frasier - was hired as a 'tourism ambassador' and starred in a video news release (VNR), which aired on 49 US TV stations. VNRs celebrating the Golden Jubilee and last month's Commonwealth Games were also produced.
Even PM Tony Blair - a popular figure in America as a result of his support for the country in its difficult time - featured in the VNR.
'Tourism is a massive industry and the Government soon takes notice if it blips,' says one high-level tourism communicator.
Last week, the BTA revealed a plan to better integrate the 'brands' of each national tourist board - for England, Scotland, Wales and Northern Ireland - into the British parent brand.
Frisby denies this is a further 'rebrand' for Britain: 'This is not a replacement campaign for Only in Britain. We want to find out how much the four values are relevant in each nation or whether there are other values.'
The English Tourism Council has co-ordinated a £1m 'welcome on arrival' PR campaign. This has involved the production of posters, souvenir packs, brochures, a hotline and web initiatives. Also, from next month it plans to contact new arrivals in the country with welcoming SMS messages the moment they get off the plane.
Some remain sceptical that PR work can entice Americans back. Observer travel editor Jeannette Hyde says: 'Time is the only thing that will heal for American tourists.' In her opinion, tourism PROs need to focus their work on travellers who have not previously visited Britain: 'Communications that seek to fill London's beds are more likely to work in new markets.'
Hyde says tourism authorities in the Caribbean - a region badly affected by the US tourist stay-at-home - have the right idea. Islands there, she says, have switched their promotional work away from the US to Europe.
She also points to the example of Scotland's Gleneagles Hotel, which has attempted to get Russians - not normally associated with luxury golf-based resorts - to fill beds vacated by Americans.
Indeed, Gleneagles PR manager Diana Scott, who admits her North American PR strategies have been scaled back since 11 September, says Russians are 'intrigued' by Scotland and have proved a welcome new market.
Russians can clearly not be a panacea for Britain's tourism industry.
But they - along with branded taxis, text messages and Blair's face on VNRs - are more than welcome for a sector already on the ropes.