DATA TAG DROPS OFF SCOPE CAUSING CTLR TO FORGET ABOUT ACFT AND INADVERTENTLY DSNDED ANOTHER ACFT THROUGH OCCUPIED ALT RESULTING IN LTSS.

Narrative

ON JAN/1992 AT WASHINGTON CTR ACR X WAS GOING NEBOUND TO PHL AND ACR Y SWBOUND WAS AT FL350. THE SECTOR I WAS WORKING HAD JUST BEEN SPLIT OUT FROM THE LOW SIDE. I NOW OWN FL350 AND ABOVE. THE SECTOR BELOW HANDED OFF ALL OF THE APPROPRIATE ACFT IN MY ALT STRATUM AND I STARTED TO SEQUENCE ALL OF MY STRIPS. WHILE IN THE MEANTIME; A DATA TAG DROPPED OFF THE RADAR SCOPE (ACR Y) AND THEN NOT KNOWING ABOUT THE MISSING DATA TAG I DSNDED ACR X TO FL330. AT THAT POINT IS WHEN CONFLICT ALERT WENT OFF. SO I STOPPED ACR X DSCNT AND TURNED HIM NWBOUND AND CLBED HIM AGAIN; AFTER CLR OF CONFLICTION I PUT ACR X BACK ON COURSE. THIS INCIDENT HAPPENED BECAUSE THE FULL DATA BLOCK KEY WAS NOT DEPRESSED SO WHEN TAKING THE HDOF; THE SECTOR APPEARED TO OPERATE NORMAL BUT IN FACT AFTER 4 MINS THE ACFT TAG DROPS OFF THE RADAR SCOPE MAKING HIM UNAWARE OF THE ACFT. THIS BUTTON SHOULD NOT BE AN OPTION TO SELECT; IT SHOULD BE KEPT DEPRESSED A TALL TIMES. IT SHOULD BE MADE TO BE LOCKED IN THE ON POS AT ALL TIMES NOT ALLOWING IT TO BE DEPRESSED. THIS WAS AND ERROR CAUSED BY EQUIP.