ZOB CTLR DESCRIBED OPDEV WHEN G4 AT FL400 LOST TRANSPONDER IN CANADIAN AIRSPACE; NO HDOF/COORD; ACFT ID IN ZOB SECTOR.

Narrative

GULFSTREAM G4 IN LEVEL FLT AT FL400. XPONDER FAILED INFLT IN CANADIAN AIRSPACE W OF BUFFALO; NY. A HDOF FROM TORONTO CTR TO ZOB WAS NOT MADE. ACFT CALLS ZOB STATING 'I THINK THAT TORONTO CTR FORGOT TO GIVE US A FREQ CHANGE CTR; WE ARE W OF FLINT; MI (FNT) AT FL400.' AS THE RADAR CTLR; I INITIATED A FLT PLAN READOUT AND ASKED THE ACFT TO SQUAWK AND IDENT THE CODE ASSIGNED FOR THAT FLT. THERE WERE NO ACFT IN MY SECTOR AT THAT ALT AND ON THAT XPONDER CODE IN THE AREA 'W OF FNT' SO I INSTRUCTED THE ACFT TO CONTACT ZOB. THE ACFT RETURNED TO MY FREQ AND SAID THAT CHICAGO WAS TOO BUSY AND SAID RETURN TO LAST FREQ. I ASKED THE ACFT IF THEY HAD A BACK-UP XPONDER TO SQUAWK AND IDENT ON THE ASSIGNED BEACON CODE. I RADAR IDENTED THE ACFT APPROX 20 MI N OF LANSING; MI AT FL400 IN MY SECTOR. AT THE TIME I WAS WORKING APPROX 20 ACFT (MODERATE TFC). I INITIATED AN AUTOMATED HDOF TO ZOB PRIOR TO THE ACFT ENTERING CHICAGO'S AIRSPACE. 1) THE ACFT FLEW THROUGH APPROX 200 MI OF RVSM AIRSPACE AT FL400 WITH NO XPONDER. NO XPONDER FAILURE WAS NOTED IN THE COCKPIT. 2) WITH A FAILED XPONDER; OTHER ACFT WOULD BE UNABLE TO RESPOND TO TCAS ADVISORIES (TA'S) OR RA'S. 3) SINCE PRIMARY RADAR IS NOT REQUIRED TO BE MONITORED AT SECTORS ENTIRELY IN THE CLASS A STRUCTURE; THERE WAS NO PRIMARY TARGET ASSOCIATED WITH A PLT POS RPT. THIS IS POTENTIALLY A FATAL FLAW OF THE NEXT GENERATION AIR TFC CTLR SYS (NEXGEN). BECAUSE THE PLT WAS ABLE TO UTILIZE A BACK-UP XPONDER AND THE AVAILABILITY OF PRIMARY RADAR AT THE SECTOR; I WAS ABLE TO POSITIVELY IDENT THE ACFT.