Narrative:

At approximately xx:xx uct, while working sector D15 at ZOA, the flight plan on air carrier X, en route to sea from ont via klamath falls, J189 was erroneously removed from the center stored computer. At the time of the incident, sector 15 was extremely busy, working moderate to mostly heavy traffic. When a flight plan is removed from the center stored computer on an active aircraft, the full data block (fdb) automatically disappears, and is replaced with a limited data block (ldb). The flight plan was removed by another controller working an unaffected sector, sector D41, by utilizing the logic override capability of the center computer. The D41 controller received a 'remove strips' message on the computer readout display on a GA aircraft with a computer identify # (cid) of XXX. He did not remove the flight progress strip from the active strip bay. A few mins later he received another strip on the same GA aircraft with a different cid. In the meantime, the computer reassigned cid XXX to air carrier X. I received the radar handoff from ZLA on air carrier X, cid XXX. While we were working air carrier X, the D41 controller tried to remove the flight plan on the GA aircraft using the cid XXX. The computer readout display gave the message 'not your control' to the D41 controller. To override this message, the D41 controller entered '/ok' into the computer. The '/ok' function overrides the 'not your control' message and allows it to be processed. After this function was entered into the computer, the computer readout display gave the message, 'accept remove strips air carrier X, XXX.' after receiving this message, the D41 controller did not notify his supervisor to attempt a search for the aircraft. At the time the remove strips message was entered into the computer, I had already initiated a handoff to sector 34, which lies immediately to the north of sector 15. Sector 34 had not yet accepted the handoff when the fdb disappeared. At the time the fdb on air carrier X had disappeared and was replaced by the ldb, I had not noticed it because I was working moderate to mostly heavy traffic at sector 15, and was performing many d-side functions which diverted my attention away from the radar scope. The ldb traversed the remainder of sector 15, all of sector 34, and all of sector 32 west/O being noticed. The controller at sector R43 noticed the ldb approximately 5 mi from his airspace, nwbnd. At that time I received an interphone call from sector R31 asking me if I ever worked an air carrier X, and asked me if he was on our frequency and would I put him on sector 31's frequency. The R15 controller checked the frequency and air carrier X was on it, and then switched to sector 31's frequency.

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Original NASA ASRS Text

Title: DATA BLOCK WAS INADVERTENTLY DROPPED RESULTING IN ACR X TRAVERSING 2 ADJACENT SECTORS AIRSPACE UNDETECTED BEFORE RADAR CONTACT WAS REESTABLISHED.

Narrative: AT APPROX XX:XX UCT, WHILE WORKING SECTOR D15 AT ZOA, THE FLT PLAN ON ACR X, ENRTE TO SEA FROM ONT VIA KLAMATH FALLS, J189 WAS ERRONEOUSLY REMOVED FROM THE CENTER STORED COMPUTER. AT THE TIME OF THE INCIDENT, SECTOR 15 WAS EXTREMELY BUSY, WORKING MODERATE TO MOSTLY HEAVY TFC. WHEN A FLT PLAN IS REMOVED FROM THE CENTER STORED COMPUTER ON AN ACTIVE ACFT, THE FULL DATA BLOCK (FDB) AUTOMATICALLY DISAPPEARS, AND IS REPLACED WITH A LIMITED DATA BLOCK (LDB). THE FLT PLAN WAS REMOVED BY ANOTHER CTLR WORKING AN UNAFFECTED SECTOR, SECTOR D41, BY UTILIZING THE LOGIC OVERRIDE CAPABILITY OF THE CENTER COMPUTER. THE D41 CTLR RECEIVED A 'REMOVE STRIPS' MESSAGE ON THE COMPUTER READOUT DISPLAY ON A GA ACFT WITH A COMPUTER IDENT # (CID) OF XXX. HE DID NOT REMOVE THE FLT PROGRESS STRIP FROM THE ACTIVE STRIP BAY. A FEW MINS LATER HE RECEIVED ANOTHER STRIP ON THE SAME GA ACFT WITH A DIFFERENT CID. IN THE MEANTIME, THE COMPUTER REASSIGNED CID XXX TO ACR X. I RECEIVED THE RADAR HDOF FROM ZLA ON ACR X, CID XXX. WHILE WE WERE WORKING ACR X, THE D41 CTLR TRIED TO REMOVE THE FLT PLAN ON THE GA ACFT USING THE CID XXX. THE COMPUTER READOUT DISPLAY GAVE THE MESSAGE 'NOT YOUR CTL' TO THE D41 CTLR. TO OVERRIDE THIS MESSAGE, THE D41 CTLR ENTERED '/OK' INTO THE COMPUTER. THE '/OK' FUNCTION OVERRIDES THE 'NOT YOUR CTL' MESSAGE AND ALLOWS IT TO BE PROCESSED. AFTER THIS FUNCTION WAS ENTERED INTO THE COMPUTER, THE COMPUTER READOUT DISPLAY GAVE THE MESSAGE, 'ACCEPT REMOVE STRIPS ACR X, XXX.' AFTER RECEIVING THIS MESSAGE, THE D41 CTLR DID NOT NOTIFY HIS SUPVR TO ATTEMPT A SEARCH FOR THE ACFT. AT THE TIME THE REMOVE STRIPS MESSAGE WAS ENTERED INTO THE COMPUTER, I HAD ALREADY INITIATED A HDOF TO SECTOR 34, WHICH LIES IMMEDIATELY TO THE N OF SECTOR 15. SECTOR 34 HAD NOT YET ACCEPTED THE HDOF WHEN THE FDB DISAPPEARED. AT THE TIME THE FDB ON ACR X HAD DISAPPEARED AND WAS REPLACED BY THE LDB, I HAD NOT NOTICED IT BECAUSE I WAS WORKING MODERATE TO MOSTLY HEAVY TFC AT SECTOR 15, AND WAS PERFORMING MANY D-SIDE FUNCTIONS WHICH DIVERTED MY ATTN AWAY FROM THE RADAR SCOPE. THE LDB TRAVERSED THE REMAINDER OF SECTOR 15, ALL OF SECTOR 34, AND ALL OF SECTOR 32 W/O BEING NOTICED. THE CTLR AT SECTOR R43 NOTICED THE LDB APPROX 5 MI FROM HIS AIRSPACE, NWBND. AT THAT TIME I RECEIVED AN INTERPHONE CALL FROM SECTOR R31 ASKING ME IF I EVER WORKED AN ACR X, AND ASKED ME IF HE WAS ON OUR FREQ AND WOULD I PUT HIM ON SECTOR 31'S FREQ. THE R15 CTLR CHKED THE FREQ AND ACR X WAS ON IT, AND THEN SWITCHED TO SECTOR 31'S FREQ.

Data retrieved from NASA's ASRS site as of August 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.