B737 Undifferentiated or Other Model
Air Traffic Control Fully Certified
Other / Unknown
ATC Issue All Types; Airspace Violation All Types
Air Traffic Control Issued Advisory / Alert
Procedure; ATC Equipment / Nav Facility / Buildings
A B757 was level at FL390 northbound on route. In compliance with SOP; I gave/received lower on the aircraft from Lorain Sector and told them to cross 85 miles south of YXU at FL330. The aircraft read back this clearance and it was correct. The sector to the north of me called to point out another Air Carrier; a westbound flight that was at FL360. While he did this; I showed him the B757; told him they would be descending and I would miss the other flight. One minute out from 85 south of YXU I asked the B757; who was still at FL390; if he would make his restriction and they said yes. I asked him to verify that they would cross 85 south and they replied they would; however they were already at that point and in conflict with the other aircraft. I called traffic asked them to report out of FL350 and no loss of separation resulted. Where I show 85 south of YXU is not where they crossed. This is not the first time. Numerous aircraft over the last several years have missed the restrictions off of YXU. This leads me to believe that either our map miss represents where YXU is from our boundary or there is a problem with DME off of YXU.
[Narrative #2 contained no additional information.]
ZOB Controller described a conflict event when an issued crossing restriction was missed; the reporter noting this NAVAID DME dependant restriction is often missed; questioning the DME and/or RADAR display accuracy.