FOI ref: FOI-2023-1164
You asked
May I please request the information on methodology of the aggregate index of air fares? Specifically, for Domestic, European, and Long-haul flights, what is the departure and return dates of the flights respectively?
We said
Thank you for your request.
To provide details of our Consumer Prices Index (CPI) Air fares Index, prices for long-haul flights are collected six months, three months and one month in advance of departure dates; short-haul prices are collected three months and one month in advance; and domestic prices are collected one month in advance. Prices are collected for flights which depart on 'index day' where possible. This is usually the 2nd or 3rd Tuesday of the month. We also include return flights in the price, these take place three weeks later for long-haul flights, two weeks later for short-haul and a week later for domestic. It is also worth noting changes in the price of air fares are recorded in the CPI in the month in which the flight departs, not when the ticket is bought. The date of travel of flight is linked to 'index day' (the day in which we collect all prices for CPI) which we can't specify in advance as it is commercially sensitive, for fear of it resulting in price manipulation, however the actual date is announced in the latest months CPI statistical bulletin, in section 8 under 'methodology information':
Consumer price inflation, UK: May 2023
For information, the index dates used in 2023 to date are:
January 2023 = 10 January
February 2023 = 14 February
March 2023 = 14 March
April 2023 = 18 April
May 2023 = 16 May
A more complete description of our air fares methodology can be found in our technical manual below, see section "9.5.5 Air fares".