RWY INCURSION AT AN UNCONTROLLED ARPT WHERE A TAXI BACK WAS REQUIRED AND ALL ACFT WERE NOT FOLLOWING CTAF PROCS.

Narrative

WHILE TAXIING FOR DEP CALL INTENTION ON UNICOM; BACK TAXI TO RWY 27 FOR DEP; THERE ARE NO TXWYS WHEN ARRIVING AT RWY BEFORE ENTERING FOR BACK TAXI A VISUAL LOOK SHOWED NO TFC. ALSO HAD BEEN MONITORING UNICOM AND HEARD NO XMISSION; UPON ENTERING RWY TO BACK TAXI SAW ACFT AT APCH END EITHER JUST LIFTED OFF OR GOING AROUND. I TAXIED OFF THE RWY AND WAS THEN ABLE TO CONTACT THE OTHER ACFT BY RADIO. REST OF TAXI AND TKOF UNEVENTFUL. PROB NOT ENOUGH POS REPORTING IN PATTERN. VISIBILITY OF ACFT LOW ON FINAL. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR INDICATED THAT THE ARPT IS USED EXTENSIVELY FOR FLT TRAINING AND HE SUSPECTED THAT ACFT Y WAS OCCUPIED WITH THAT ACTIVITY. HE HEARD NO CTAF CALLS UNTIL AFTER ACFT Y WAS OBSERVED AND THEN Y MADE A CALL. THE RPTR ASSUMED THAT TRAINING CONVERSATION OR A TURNED DOWN RADIO CAUSED Y TO BE OUT OF THE CTAF LOOP. THE RPTR SAID THAT THERE IS A HUMP IN THE RWY; WHICH TO SOME EXTENT; OBSCURES THE END WHEN THE RWY IS ENTERED AT THE FBO TXWY TO BEGIN TAXI BACK. THIS MAKES THE CTAF COM MORE IMPORTANT.