A person From the Civial Air Patrol sent me the following information on black boxes and searching for aircraft. Unfortunately locating an aircraft that has gone down in the water is somewhat like looking for a needle in a haystack, especially if there are no witnesses or floating debris.
Try and picture how difficult it would have been for Flight 800 to have been recovered if it had gone down in deep water, such as that of the Triangle, and without any witnesses? Today even with all the resources of the United States Government behind the investigation.It took over a year to determine a faulty fuel line MAY have been the blame, and that is with the recovery of most of the aircraft.
In the section on "The Ocean Floor The "black box" you are referring to is called a Flight Data Recorder and is of no use in finding an aircraft - they are used by the National Transportation Safety Board to try to figure out the cause of the crash. The electronic device that *does* figure into searches for crashed aircraft, is called an Emergency Locator Transmitter, or "ELT" for short. These are small radio beacons that automatically go off in case of a crash, and small planes absolutely *do* have them, with only a very few exceptions such as ultralights. Many searches I've been on have started with an "ELT hit" by the constellation of satellites monitoring the entire world for just such an event. Nevertheless, if an aircraft crashes *into the water* and then is submerged, the ELT signal will not be heard since the ELT is submerged, so the effect is, as you note, that it is quite difficult to find a plane that has crashed into the water. We recently had an aviator crash into Lake Michigan only a few miles from General Mitchell International Airport, and it took a lot of searching by a very professional marine salvage company, and very expensive side-scanning sonar and an underwater robot (!) to locate the wreck, in 180 feet of water. And this was just off a major city, with radar tracks to give a good idea where he was!
*Similar equipment was used in the recovery of JFK Jr. small aircraft off the coast of Martha's Vinyard. It took close to a week and resources from the Cival Air Patrol, Coast Guard, and U.S. Navy to find his aircraft in approximately 100 feet of water and they also had a good idea where to look for him.
Such and search and recovery effort would have been practically impossible twenty years earlier.