Simon Calder: If life's too short, how about a BAwayday?

More is more: that is conventional travel wisdom on the benefit of spending time in a destination. You need to devote weeks, months or even years to get under the skin of a place.

The trouble is, for most travellers that kind of commitment is impossible. And even for those generously endowed with both time and money, the argument looks suspect given the annoyingly finite limits on our lifespans. Suppose you were given one month to visit Ireland: would you really want to spend every moment of it in Dublin, rather than immersing yourself in the capital for a few days before exploring all corners of an island of wonders and pubs?

The city break, officially invented by The Independent Traveller in 1989, rejects the corollary that "less is less". The thesis of our 48 Hours series is to prescribe a range of cultural and culinary experiences to pack into an intensive couple of days. The shorter the stay, the more energy you can expend. (At this point, allow me shamelessly to plug our new 48 Hours ebook, featuring a score of capitals including Paris, Helsinki and Lisbon, for £2.99; see bit.ly/48ebook).

Now British Airways is taking the concept of the short break to the logical conclusion: a trip where you can leave the toothbrush behind. This week, the airline introduced day-trip fares from Heathrow to six cities for under £100, if you fly out and back on a Saturday or Sunday. It's called, at least by me, a BAwayday. The concept is seductive: an artistic adventure in Edinburgh or Vienna; a pub crawl in Dublin or Munich; or a speedy spiritual journey to either side of Christianity's sectarian divide in Rome or Geneva.

Of course, you have been perfectly able to book day trips at weekends (or any other day of the week) with BA or other airlines for decades. What is different is the pricing, best illustrated between Heathrow and Ireland. Booking a few days ahead, the cheapest day-trip return to Belfast is £151, which is roughly what you would expect. But to Dublin, the fare is just £79.

British Airways is playing a canny game to fill empty seats. On many of its European routes, the same number of flights operate every day. But demand at weekends tends to be weak. How tostop flying so much fresh air around on Saturdays and Sundays without "cannibalising" earnings from existing customers who might be prepared to pay higher fares? The airline is testing the notion that some people will relish the chance to explore a great city and still get home in time for bed – with no need to pay for a hotel or to pack more than a copy of The Independent and an ebook reader. If demand materialises (presumably from travellers living close to Heathrow), expect a rapid roll-out of day trips to other destinations with early departures and late arrivals.

On so short a trip, public transport from the destination airport into town becomes critical. Among BA's initial half-dozen cities, all the Continental options have rail links, while Edinburgh and Dublin visitors must make do with a bus.

The prime choice is Geneva. The train from the airport's own station take only seven minutes to the centre, and the city dispenses free rail tickets from a machine in the baggage hall.

Given the environmental impact of flying, expect strenuous objections to the BAwayday. Surely no journey is so needlessly damaging as a frivolous day trip to a European city? The short-term riposte is straightforward: these planes will be flying anyway, and the airline is simply trying to increase the number of people on board. Longer term, it is a harder to sustain argument, because future demand from day-trippers may make marginal services viable.

More flying visits ...

Travellers with the temerity not to live within easy reach of Heathrow or Gatwick – perhaps near Manchester, Leeds, Newcastle or a Scottish airport – may soon be offered the chance of a BAwayday to anywhere they like, so long as it's Heathrow or Gatwick. But BA's move led me to check the day-trip possibilities on other airlines a fortnight from now. Seven precious hours in Edinburgh from Southampton is currently £122 with Flybe; from the Scottish capital, 10 hours in Dublin costs £75 with Ryanair; and for £116, easyJet will take you from Bristol to Geneva for 13 hours in a civilised and beautiful city.

... and happy returns

From BA's perspective, there is always the danger that passengers will misuse the day-trip fares by using it for cheap one-way flight. On Wednesday, when the new day-trips were announced, I looked at prices for Saturday morning from Heathrow to Vienna. A day trip came in at £97, but the one-way fare was £145. Half as much again, for flying half the total distance. To Geneva, a round-trip cost £78; the cheapest one-way was nearly twice as much.

Buying a return when you intend to fly only one way is known as "tariff abuse". It is explicitly frowned upon. BA's rules imply that if you fail to make the return journey, it will come after you for the extra fare: "Where you change your travel without our agreement and the price for the resulting transportation you intend to undertake is greater than the price originally paid, you will be requested to pay the difference."

I am not aware of the airline ever seeking to recover cash from a no-show. Anyone considering another form of tariff abuse, such as buying a Dublin-London-New York ticket for less than the Heathrow-JFK fare, should beware. The £2,000 saving on a one-way Club World ticket applies only if you begin your journey in the Irish capital. So you must get to Dublin first. Just don't be tempted to fly from Heathrow on a BA day-trip and throw away the return half.