A coffee-break chat at the recent Airline Business Network USA conference in Tampa, Florida, highlighted the blind faith airlines are willing to show in the aviation industry's ability to deliver on its promises, despite a hardly stellar track record in recent times.
When talking to an airline marketing chief about which new generation engine his airline might choose to power the Airbus A320neos it has on order, he joked that neither of its engines had actually left the drawing board yet. "It's funny," he said, "Airbus launched this new engine option, but when you ask them about the engines they say you'll have to go and speak to Pratt or CFM. And the engine makers have got some ideas about the technology they'll employ, but neither of these engines actually exist yet."
Okay, he was perhaps being slightly flippant, but the point he was making was valid.
Since launching its A320neo in December 2010, Airbus's chief sales man John Leahy has racked up an eye-watering 1,300 orders for his re-engined narrowbody. "We'll have quite a few hundred more Neo orders this year, as well," he says.
Although Boeing only joined the party in July with its 737 Max, it is already boasting more than 1,000 orders and commitments. Deliveries of the A320neo are advertised as starting just over three years from now, and the Max should follow less than two years later - perhaps sooner if Boeing can find some shortcuts.
With CFM International and Pratt & Whitney promising double-digit efficiency gains, expectations are high among the airlines that there will soon be relief to the threat of sustained high fuel prices. Airbus and Boeing have capitalised on this "flight to efficiency" with order numbers that surpassed even their wildest dreams.
Once upon a time the term "paper airplane" was used by marketeers in a derogatory way to dismiss claims by a rival about the game-changing qualities of an in-development design. But, as we examine in this month's special report, the swift reactions last year from the "old guard" to make a grab for the new engine technology adopted by "insurgents" such as Bombardier and Comac has levelled the playing field somewhat in this regard.
Leahy likes to tout how the Neo will deliver a 15% fuel consumption saving but retain "95% commonality" with the current A320. But he forgets to mention that this is for the airframe only, and excludes the all-new hair dryers being slung under each wing.
As the marketing man at Network USA pointed out, the whole premise on which the 2,400 Neo/Max orders so far have been placed exists currently only in the minds of the boffins who are inventing them.
We should get to see a little more of Pratt's hand later this year, when the first of its geared turbofan generation breaks cover - hopefully - on the Bombardier CSeries. (One seasoned observer cruelly jokes that, given the relative sales tallies of the CSeries and the re-engined A320, the Bombardier jet could be little more than a proof-of-concept hack for the Neo's GTF engine technology!)
As well as the hardware delivering on its promises, the other key challenge for all these paper airliners is meeting their development schedules. As Airbus and Boeing have proved with all recent programmes, achieving that is far from certain.
Not since the introduction of the high-bypass turbofan engines on narrowbodies over a quarter of a century ago has a single hardware change-out delivered such significant efficiency gains for the airlines' short-haul networks. And clearly the timing couldn't be better, so it's no surprise there's been a headlong rush for this promised land.
No wonder there are probably one or two engineers in Cincinnati and East Hartford feeling the weight of expectation on their shoulders.