What is a black box, what can it tell us, and have the data recorders been found from Flight 5342 and the Army's Blackhawk?

Some have suggested that it stems from Hussenot's device, because it used film and "ran continuously in a light-tight box, ...

Black box recovered as crew and passengers in medical jet crash identified - All six passengers on board the Learjet 55 ...

An American Airlines regional jet went down in the Potomac River near Ronald Reagan Washington National Airport after ...