1.   Although Perry suggested Thursday that the second beacon might have been broken on the day of the crash, Croatian aviation officials have insisted that both beacons were operating.

2.   Did the pilots ever tune in the second beacon?

3.   Investigators have determined from the wreckage that the pilots, Capt. Ashley J. Davis and Capt. Timothy W. Shafer, never tuned in the second beacon.

4.   Perry said Thursday that the second beacon might not have been working, but investigators Friday contradicted that.

5.   The pilots might have been unable to tune in the second beacon, or had trouble navigating away from the first one.

6.   Until they tune in the second beacon, pilots must calculate their course from the tail end of the ADF needle as it points backward at the first beacon.