Simon Calder's Holiday Helpdesk: Why do air travel prices change so much?

Every day our travel guru answers your travel questions

Q Why is it, if you book a one-week flight, the fare is a certain amount; if you book the same departure date but two weeks’ duration the price goes up £20 or £30; if you book again the same departure date but for 21 days duration the price increases by almost £100? I am looking at flights from Birmingham to Chania on Monarch. Do the airlines think if you can afford 3 weeks holiday you can afford to pay more for your flights?

David Bailey

A No. Monarch, like all short-haul, low-cost airlines, seeks to fill as many seats as possible on a flight, while extracting maximum earnings from each traveller.

Every flight is looked at individually. If demand for a particular departure is weak, fares will be low in an attempted to entice people on board. If demand is high, prices will go up. These changes happen entirely independently of individual travellers’ needs. The most extreme example in recent times was Malaga to Gatwick at the end of last August; for late-bookers, the inbound flight cost £500, regardless of when you travelled out.

I imagine the reason you are seeing apparently sharp increases is because you are booking around 20 July. Demand from British families on holiday in Crete will be low at the end of July, but steadily increases as the school summer holidays continue into August.

At other times of year, ie later in the summer, the opposite effect would apply: you would pay less for two weeks rather than one, and perhaps a lot less for three weeks.

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