Reply #1: also from the same article

[paulthompson]

more clues to the altitude of Flight 93:

Ms. TAYLOR: Yeah. And then the transponder came back on. We got two hits off the transponder. That's something we've always wanted to know. Why did the transponder come back on? Because the hijackers had shut it off so that they couldn't be tracked, even though we were still tracking them. Now we were getting an altitude readout on the airplane. I can't remember the precise numbers, but it was around 6400 feet, and then around 5900 or 5800 feet. And we're thinking, 'Oh, you know, maybe something's happened, maybe this isn't what we think it is.'

BROKAW: (Voiceover) But minutes later, at 10:03, the transponder shuts off again. Flight 93 disappears from radar.