Imagine: you call a cab, and at the appointed time a stretched limousine draws up outside. You might be intrigued and impressed, but also anxious about the likely fare. Then you discover that the price is actually one-third lower than usual. That is the terrestrial equivalent to the biggest aviation story of the summer: the world's largest plane is to fly on one of the shortest international routes.
The longest non-stop flight you can currently take from Heathrow is to Singapore: a joy-consuming, bum-numbing 14-hour haul across eight time zones and 6,744 miles. The shortest international links? To the trio of the nearest Continental capitals, Amsterdam, Brussels and Paris.
What the flights to Singapore and Paris have in common, besides their starting point, is that they both give you the chance to experience the world's most modern aircraft. Starting next Saturday, the aeronautical giant that is the Airbus A380 is to be deployed between Heathrow and Paris Charles de Gaulle.
Last time I flew that route, Air France used a cosy little Airbus A318, seating just 123. At weekends this summer, the A380 makes a guest appearance on lunchtime flights, allowing Air France ostentatiously to parade the world's biggest passenger-carrying machine between western Europe's two largest cities. And passengers enjoying long-haul luxury on a short hop pay less than two-thirds of the usual Air France fare of £120 return.
According to airfrance.co.uk, you should "Book your flight on the A380 for £80 return. Hurry, only a few seats remaining." Both those sentences are wrong. Test bookings suggest the standard fare is actually £79 (£66 of which is claimed to be "taxes"); and so far all the departures I have tested are wide open for availability.
To experience the world's largest airliner, and more importantly to reach the "city of light" at a sterling-friendly fare, you need to look at flight AF1981 outbound, AF1980 returning, from Saturdays to Mondays until the end of August, plus every Friday in July. Happily, these dates coincide with the almost total disappearance of those elusive £69 return fares from London to Paris on Eurostar; meanwhile, BA's lowest fare is £117 return.
Very large aircraft are designed to carry hundreds of people over very long distances. Emirates flies the A380 almost 7,500 miles from Dubai to Sydney. Consider the logistics of boarding 500-plus passengers, together with the sheer energy-draining effort involved in getting a giant jet off the ground, the immense capital cost of these big jets, and the heavy maintenance bill for each take-off and landing cycle: airline economics seem logically to rule out short hops.
Yet Virgin Atlantic operates plenty of very short hops on Boeing 747 flights to the Caribbean: from Gatwick to Grenada, the plane first flies to Tobago. By combining these two "niche" islands just 88 miles apart on a single Jumbo service, the airline can command sufficient extra revenue to justify the operational extravagance. Now Air France is adopting the principle of "intelligent mis-use" of big planes.
Quelle surprise? Yes, and no. There is no obvious untapped market to be served. But I reckon the main motivation for Air France is simply: because it can.
The plane can earn money between long-haul flights rather than staying on the ground in Paris. It reminds Eurostar that it does not have a monopoly. And it delivers another blow to strike-prone British Airways, which has cancelled today's lunchtime departure from Heathrow. Travellers who experience the service aboard Air France's A380 may be tempted to book long-haul flights via Paris to the US or South Africa several years before BA's "superjumbos" arrive.
Travel has quite enough awards already, but were I asked to nominate an extra category it would be the "Leggies", presented to the airline that provides the greatest personal space.
Contrary to popular belief, airlines rather than manufacturers decide a plane's capacity. Airlines configure them as they wish up to the certified maximum (853 passengers for the Airbus A380).
The least-crowded superjumbo is flown by Qantas, which carries only 450 people on board a plane that could legally carry almost twice as many. Singapore Airlines goes with 471, Emirates has 489 seats and Lufthansa opts for 526.
Perhaps surprisingly for a nation whose leading philosopher concluded "Hell is other people", Air France crams more passengers on to its A380s than anyone current operator: 538. But a small airline based on the Indian Ocean island of Réunion is to go one better (or worse): from 2014, Air Austral will pack in an all-economy payload of 840 passengers. Now where's that call button?