The hijacked aircraft that blew up the World Trade Centre also blew away the survival plans of the world's big airlines.
It was a killer blow to an industry already on its knees following heavy punishment from the regulators and a tough fight with the world's economies.
These carriers took a long time to recover from the aftershock of 11 September. Once on their feet again, however, they moved swiftly and decisively, chopping deep into their big cost centres.
Whereas previously they had been making timid cuts, watched over by hostile union bosses and anxious board members, now they felt free to get to work, slashing capacity by up to 20 per cent, cutting pay cheques and culling thousands of staff.
Once this frenzied impulse had been sated, they turned their attention towards their customers. But the low-cost carriers had beaten them to it by wooing customers with seductive fare offers.
These start-up airlines were doing what they do best - selling seats from as little as £10 to tempt the nervous nellies back into the air.
So instead of cutting back, they bounced back, and what's more, it seems to be working.
While traffic is down for the big carriers and BA has dropped out of the FT 100 index, Ryanair's figures have taken off by nearly 40 per cent.
Across the pond, the picture is much the same. The mainstream airlines lost a staggering $6 billion last year while Southwest, the cheeky low-cost carrier, is now worth more than the big six American airlines combined.
The big six airlines are now focused towards the back of the plane and the territory already occupied by the low-cost wheelers and dealers.
This promises to be a bruising battle. No more ads featuring smiling trolley dollies in the glossy magazines. That's all been swept aside with ludicrous offers such as Airmiles giving away two free flights for the price of a crate of wine and culminating in Ryanair's one million free tickets offer.
These promotions hark back to the period following the Gulf war a decade ago when BA gave away every seat on all its aircraft for a day under the banner of "The world's biggest offer".
The big difference this time round, however, is that the threat of war continues and with it come escalating fuel costs, high security and insurance bills combined with further deregulation and an uncertain economy.
Poor business travellers have been forced to desert their pampered privileges and adopt a more modest lifestyle. It comes as a nasty shock for those used to turning left when they board an aircraft.
What's more, few campaigns highlight the benefits of premium travel, thus playing into the hands of the penny-pinching travel managers who are bombarded with low-fare offers.
All this has bred a new breed of business jet-setters who forego sumptuous luxury to join the bucket-and-spade brigade at the back of the plane.
These new strivers are jockeying to impress their bosses with claims of saving thousands flying with start-up airlines to various remote airfields while eating their take-on sandwiches.
And therein lies the rub for the traditional airlines. The new carriers are no longer attracting just hard-up tourists reluctant to spend all their holiday budget on airfare - they're also tempting the business travellers in large numbers.
Once used to this cheap travel, there's no going back. This could spell disaster for the big airlines. They're already dangerously overloaded with high costs. Unless they can offload some of this baggage they'll go the way of PanAm and TWA.
So just what does this mean for an already beleaguered advertising industry?
Well, despite all the gloom and doom, the airline sector's ad budget has actually taken off from £71 million to £75 million. This increase has been driven by the low-cost carriers such as easyJet, which have nearly doubled their spend and are now flying dangerously close to BA's £11.8 million, down from £14.3 million in 2000/01.
But this agency cash is unlikely to attract the best creative talent, who once fought tooth and nail to work on airline accounts.
No longer are they lured by the prospect of producing mould-breaking commercials using top-flight directors in exotic locations. An agency's role nowadays is reduced to working on a production line churning out short-term discount promotions, with the only challenge being to squeeze as many cheap fares into the smallest space. The rich heritage of award-winning campaigns remains a thing of the past.
But low-fare advertising doesn't have to be so lacklustre. When Go launched its low-fare campaigns in the 90s they were lively and contemporary, with a feeling of style and affordable quality.
But the airline ads that have recently dominated the press led by Ryanair and easyJet are dismal, only marginally more imaginative than personalised car number plate ads. They discharge few creative sparks reflecting the state of the airline business, with each successive ad shouting louder.
However, among all these barren ads that form the landscape in the aftermath of 11 September, there are the first signs of creative life. Virgin has kick-started its Upper Class promotions; in Argentina, Aerolineas Argentinas has risen from the ashes with a brand-building campaign and BA's back on the television.
Let's hope that future airline ads will recapture some of the glamour that's still part of overseas travel. And let's banish the tacky stuff under Tracy Emin's unmade bed where it belongs.