Research by the French '' Bureau d'Enquêtes et d'Analyses pour la Sécurité de l'Aviation Civile '' ( BEA ) has shown that it has had a 90 % survival rate spanning 27 air accidents over the sea . The ULBs fitted in Air France Flight 447 , which crashed on 1 June 2009 , were certified to transmit at 37.5 kHz for a minimum of 30 days at a temperature of 4 °C . Investigating the crash , the BEA recommended that FDR ULBs ' transmission period be increased to 90 days and for " airplanes performing public transport flights over maritime areas to be equipped with an additional ULB capable of transmitting on a frequency ( for example between 8.5 kHz and 9.5 kHz ) and for a duration adapted to the pre-localisation of wreckage " ( i.e. with increased range )
Air France Flight 447
Air France Flight 447
Underwater locator beacon