The US Navy this morning announced that they are joining the search for the missing Air France airliner, which disappeared off of radar early yesterday morning while en route from Brazil to Paris. The situation leaves me wondering … isn’t there global positioning satellite (GPS) capability on board these planes?
The answer is “yes” but the signals are not automatically sent to air traffic controllers – this according to Reuters in an article this morning titled “How Planes Get Lost“. 
The United States is working on such a system. It’s intended implementation date: 2013.
In the meantime, there still is no evidence indicating what may have happened to that particular Air France plane. As was reported this morning by Steve Huettell in the St. Petersburg Times, “If a plane crashes into the water, a homing beacon transmits an ultrasonic ping that can be picked up by sonar and underwater hydrophones. The signal carries to the surface from nearly 4 miles underwater for 30 days.” 
No such signal has yet to be reported.
 Reuters, FACTBOX: How planes get lost, Wed Jun 3, 2009 4:32am IST, http://in.reuters.com/article/worldNews/idINIndia-40052920090602
 St. Petersburg Times, Air France jet’s black boxes are deep in Atlantic, June 3, 2009, Steve Huettel, http://www.tampabay.com/news/business/airlines/article1006804.ece