The events of 9/11 as they unfolded through actual audio.
P3 Sonobuoy Sonar System Air Drop
Footage of a P3 Sonobuoy being deployed from an aircraft. They are using these devices to search for missing Malaysian airliner MH370. A sonobuoy (a portmanteau of sonar and buoy) is a relatively small (typically 5 inches or 13 centimetres, in diameter and 3 ft or 91 cm long) expendable sonar system that is dropped/ejected from aircraft or ships conducting anti-submarine warfare or underwater acoustic research. The buoys are ejected from aircraft in canisters and deploy upon water impact. An inflatable surface float with a radio transmitter remains on the surface for communication with the aircraft, while one or more hydrophone sensors and stabilizing equipment descend below the surface to a selected depth that is variable, depending on environmental conditions and the search pattern. The buoy relays acoustic information from its hydrophone(s) via UHF/VHF radio to operators on board the aircraft. Read more at http://en.wikipedia.org/wiki/Sonobuoy