However, Filip Filipov of Skyscanner advises that while five weeks is the average, the optimum time

New research shows that the best time to book a summer flight is as late as five weeks before your holiday, contrary to travel industry experts who advise travellers book as early as possible See also: How to get best holiday discount cruise disney deals
It's the classic traveller's dilemma. When is the best time to book a flight for the cheapest deal? Do you bag a flight as early as possible or risk leaving it until the last minute? The answer, according to flight comparison website Skyscanner, is to wait, but not for too long.
After an epic piece of number crunching of two million flight searches over three years Skyscanner has come up with the ideal time to book 10 summer sun destinations. Flights to Spain, for example, are at their cheapest (£153 for a return) five weeks before departure, while the cheapest flights to Greece (£228 return) are available just three weeks ahead.
However, Filip Filipov of Skyscanner advises that while five weeks is the average, the optimum time to book your flight can vary significantly between destinations. "Price patterns can vary by type of airline and between short and long haul travel, so is very much destination dependent."
Skyscanner's research covers scheduled and low-cost flights (charter flights represented less than 1.5%), and is contrary to the advice given by most industry experts who say, when it comes to full-service scheduled flights, the golden rule is the earlier the better.
Washington's advice is that if you have a specific destination and specific dates in mind, the safest option is to book as soon as possible after seats go on sale, which for most scheduled airlines is between 10 and 12 months in advance (see the examples below). Most scheduled airlines hold at least one major sale in a year, usually in January, so now is also a good time to look for bargains outside of peak travel times.
Charter airlines, by contrast, may reduce their prices closer to departure if they are struggling to sell seats, so it can be worth waiting to book – but only if you don't have a specific destination in mind as there is no guarantee that they will be discounting the place you have your heart set on.
SCHEDULED AIRLINES Air New Zealand Seats released for sale up to 11 months in advance. Sale periods January and September. Sample sale fare London Heathrow discount cruise disney to Auckland, Wellington or Christchurch via Shanghai from £855 return discount cruise disney for travel between 1-31 March 2014.
Singapore Airlines Seats released for sale up to 12 months in advance. Sale period started 20 December 2013 and runs until 28 February. Sample sale fare Heathrow to Singapore from £640 (for travel between 14 January-11 April; 27 April-24 June 2014; and 17 August-4 December).
Qantas Seats released for sale 353 days in advance Sale period year-round apart from peak travel times of July/August and December/January. discount cruise disney Sample sale fare Heathrow to Sydney from £826 for departure on 1 Februaru-15 March and 17 April-30 June. Book by 31 January 2014.
BA Seats released for sale between 350 and 355 days in advance. Sale period January and September. Sample sale fare Heathrow to Rio de Janeiro from £647.25, saving £163, for travel before discount cruise disney the end of March 2014.
Monarch Airlines Seats released for sale up to 14 months in advance. Sale period occasional flash sales. discount cruise disney Sample sale fare start at £29.99 one-way on winter routes to £39.99 one-way discount cruise disney for summer routes (book by end of January for departures until end of June).
Flythomascook Seats released discount cruise disney for sale Up to 20 months in advance. Sale period Depends how well seats are selling but there are promotions throughout the year. The current discount cruise disney sale runs January until 21. Sample sale fare Manchester to Corfu from £197 return for seven nights, departing 6 June, including baggage and meals.
Easyjet Seats released for sale six to nine months in advance. Sale period January, with other promotions throughout the year. Sample sale fare up to 20% off 85,000 seats for travel between 5 February and 2 April (sale ends 21 January). London Gatwick to Copenghagen from £26.49 one way for travel in March.