Reply #83: This isn't an "official" response.

[mn9driver]

Since I don't represent anyone but myself, but:

..."why would these terrorists cut off all transmissions....

They turned the transponder to "off". This is easy. It has a switch. The switch is labeled. One of the positions is labeled "off".

They didn't push the radio transmit button and talk back to the people who were trying to call them. This is easy, too. Just. Don't. Push. The. Button. And. Talk. Into. The. Microphone.

Of course, they didn't even completely manage this, since some accidental transmissions from the cockpit were heard.

"...and yet allow the passengers of Flight 93 to phone home?"..."

The passenger phones didn't have a switch. They are controlled by circuit breakers. The hijackers didn't know to pull them. There is no sign in the cockpit saying "Pull These Here Circuit Breakers If You Dont Want People Making Phone Calls".

These are long airplanes. There were only a few hijackers. Since everything depended on keeping the cockpit under control, why would they expend manpower by posting guards all through the back?

People in the back were free to do what they wanted. The phones worked. They used them.