But only if they could actually pick up the road's transponder signals.

The transponder signal continued to wink on the computer screen.

"We must have lost our lock with the other transponder signals when they raised their shields."

All he had to do was lock onto its transponder signal, and the computer would navigate him straight there.

"I had his transponder signal and primary target just a moment ago-now it's gone."

They did this on 9/11 when the transponder signals for three of the aircraft disappeared.

Vaughn would move on toward the source of the transponder signal alone.

Ever since he found out about the transponder signal, he's acted as if nothing else matters.

Hours later, the first transponder signals were picked up.

He aimed the radio at the southern bore hole and searched for the transponder signal.