A LR55 FO SELECTED THE FMS 'HOLD' BUTTON PUTTING THE ACFT INTO HOLDING 20 NM FROM THE ASSIGNED HOLD. THE CONFUSED CREW DID NOT UNDERSTAND THE BUTTON'S FUNCTION.

Narrative

WE WERE #2 FOR THE GPS APCH. THE CTLR GAVE US A HOLD AT THE IAF. I WAS FLYING TOWARD THE FIX AND SLOWED DOWN TO MINIMIZE THE HOLD. I WAS ABOUT 23 MI FMS DISTANCE FROM THE FIX. THE FO STARTED ENTERING THE HOLD AT THE GPS FIX. ALL OF A SUDDEN THE AIRPLANE STARTED TURNING TO THE R. I THOUGHT AT THE TIME THAT IT WAS TURNING INTO THE HOLD. I QUESTIONED THE FO AS TO WHY THE AIRPLANE WAS TURNING AS I DISCONNECTED THE AUTOPLT AND KEPT THE AIRPLANE FLYING STRAIGHT. WE ARGUED AS TO WHERE THE ACFT WAS. HE SAID IT WAS OVER THE IAF. I SAID WE WERE STILL 20 MI AWAY. HE SAID THE FMS SAID THE ACFT WAS OVER THE FIX. I LOOKED DOWN AND THE FMS SHOWED FROM THE IAF AND TO THE NEXT FIX ON THE APCH. I THOUGHT THAT I MUST HAVE BEEN MISREADING THE EARLIER FMS DISTANCE INTO THE HOLD. THE CTLR THEN ASKED US WHAT WE WERE DOING. WE TOLD HIM WE WERE HOLDING BUT HE SAID WE WERE STILL 20 MI FROM THE FIX. HE THEN GAVE US VECTORS. I RESET THE FMS AND WE VERIFIED MULTIPLE TIMES UP TO THE APCH WITH THE CTLR THE BEARING AND DISTANCE FROM THE IAF AND THEN SHOT THE APCH WITH NO FURTHER INCIDENT. I WAS NOT SURE WHAT HAPPENED BECAUSE IT DIDN'T MAKE SENSE UNTIL I QUESTIONED THE FO AS TO WHAT HE DID AND LATER LOOKED IN THE FMS MANUAL. I ALSO COULD NOT VERIFY THE FIX BECAUSE IT WAS A GPS FIX WITH NO OTHER WAYS TO IDENT. ANYWAYS AFTER INVESTIGATION; I FOUND OUT THAT THE FO DID NOT ENTER A HOLD BUT RESET THE POS OF THE FMS. I FOUND OUT YOU CAN DO THIS BY USING THE HOLD BUTTON WITHOUT SELECTING A SPECIFIC FIX. THE NEXT TIME I GET A SITUATION WHERE THERE IS A DISCREPANCY AS TO OUR LOCATION WITH NO MEANS OF VERIFYING IT BY OTHER NAV; I AM GOING TO VERIFY WITH THE RADAR CTLR. I ALSO RECOMMENDED TO THE COMPANY THAT THEY DO MORE TRAINING IN THE USE OF THE FMS AND MORE SPECIFICALLY HOW TO ENTER A HOLD BECAUSE FOR THIS MODEL OF FMS IT CAN CAUSE YOU REAL PROBS IF YOU DO NOT KNOW HOW.