It is used by both aircraft brokers and a number of financial institutions to estimate the future value of aircraft. The Airliner Price Guide, established in 1985, is published by ACI Aviation Consulting. It provides prices for new and used commercial aircraft and other data such as engine values. The print version of the guide is issued twice a year. An online service is updated in real time. The International Bluebook is a free online service which offers general bluebook figures for jet aircraft models and conditions. The site does not provide calculations for individual aircraft, but these may be obtained via dealer’s sites or on jet aircraft multiple listing service (MLS) sites which use the service.