The Black Boxes...

[HumanShell]

Do they have a homing device inside them? They said they have "an idea where the black box might be" in the Pentagon, but they can't go after it because of how unstable the building is.

 

[talonracer]

Yes they have locating beacons but they only last for so long.........trust me they will find the boxes on all 4 aircraft. BTW the "black boxes" are actually orange...........

 

[alptraum]

Yes they have a beacon, but the signal may be distrorted since it's under all the rubble, which may be why there was speculation on it's location.

 

[HumanShell]

DAMN! They just said that the Black Boxes can be easliy disabled from the cockpit by flipping a circuit breaker. They speculate that since the hijackers kept pilots from initiating the "hijack distress" switch, there is a high chance they knew about how to turn off the black boxes.