CL60 EXPERIENCES TRACK DEV DUE TO HOUSEKEEPING ERROR.

Narrative

10-15 MI S OF ZZZ; CTR INQUIRED IF WE WERE STILL ON TXWY JX. WE LOOKED AT THE AUTOPLT AND IT WAS IN LNAV AND ALT WITH ZZZ STILL AS THE NEXT WAYPOINT. CTR TURNED US TO A HDG OF 270 DEGS. I ASKED IF WE SHOULD INTERCEPT JX ON THAT HDG. CTR STATED HE WOULD LIKE US TO GO DIRECT TO ABC; 'IF WE WERE ABLE.' I READ BACK AFFIRMATIVE; AND WE FLEW DIRECT ABC. THE REST OF THE FLT HAD NO OTHER PROBS. WHILE TRYING TO FIGURE OUT HOW THE AUTOPLT COULD HAVE MISSED THE TURN; WE REMEMBERED THAT THE COPLT WAS FLYING AND WAS ALSO CLEANING THE SCREENS AND DUSTING THE COCKPIT IN CRUISE. WE HAVE A COLLINS FMS 6000 INSTALLED. HE HAD INADVERTENTLY BUMPED THE AUTO/INHIBIT BUTTON ON THE FMS; XXR; WHILE HE WAS DUSTING. THIS CAN BE SELECTED OR BUMPED WITHOUT ANY EXECUTE. ALL OTHER DATA THAT IS CHANGED ON THIS FMS HAS TO BE FOLLOWED UP WITH A DELIBERATE BUTTON SELECTION OF THE EXECUTE KEY. THERE IS NO WARNING; ADVISORY; CAUTION; OR ANY OTHER INDICATION THAN THE GREEN 'AUTO' TURNS TO A GREEN 'INHIB' ON THE FMS. SINCE IT WAS NOT KNOWN IT WAS SELECTED; THERE WAS NO REASON TO LOOK AT THAT LIGHT. WHEN WANTING TO TIDY UP THE COCKPIT; I BELIEVE IT TO BE IMPERATIVE THAT EACH PLT IS CAREFUL OF WHAT HE OR SHE IS TOUCHING. THIS COULD BE A HIDDEN 'GOTCHA' FOR ANYONE; UNLESS YOU ALWAYS WATCH THE AUTO/INHIB SEQUENCE AFTER EACH WAYPOINT.