Information about sonar and side-scan sonar is presented in the short course
Sonar Signal Processing Jul 14-16, 2009 Beltsville, MD
The sonar search for the Air France Flight 447 flight and voice recorder continues with out any reported success. The underwater sonar has an acoustic frequency of 37.5kHz, transmitting initially with 1,060 dynes/cm2, and has a battery life of at least 30 days. Maximum detection range is 2–3km. The water depth is about 3500 m, so a towed sonar is required to get deep enough to have a chance to hear the pinger.
There is useful information at
French authorities have dispatched five ships: IFREMER research vesselPourquoi Pas; two tugboats, Fairmount Glacier and Fairmount Expedition; naval frigateVentôse; and nuclear submarine Emeraude.Ventôse has assisted with recovery of floating debris and bodies. Emeraude will conduct an initial search listening for the black-box pinger. Once this has been located, Pourquoi Pas shall carry out a side-scan sonar survey and there are plans to then deploy a mini-submarine to carry out a detailed photographic survey leading to recovery operations.
The accident location is 1,000km from the Brazilian coastline and the sea floor is extremely rugged (making side-scan sonar operations troublesome) and around 3,500 metres deep (making it difficult to detect the black-box pinger with a maximum range of 2–3km). Both operations will require a submersible or deep-tow capability for sensor deployments. Subsequent recovery of substantial aircraft parts will be an almost-impossible task and operations will probably be limited to flight recorder recovery and a detailed sonar and photographic survey.