AN ALT XING RESTR IS NOT MET BY THE FLC OF AN MD80.

Narrative

WITH ZOB ON ARR DSCNT (POLAR 1) FROM ORD TO DTW. INITIALLY CLRED DIRECT FNT; THEN GIVEN HDG TO DIRECT POLAR +/-3 MI EITHER SIDE OF POLAR INTXN (DXO 41 DME). WE DID NOT HAVE GPS; SO HITTING POLAR EXACTLY WAS NOT POSSIBLE. WE WERE GIVEN DISCRETION TO 12000 FT AND CROSS POLAR INTXN AT 12000 FT. ALSO; ZOB TOLD US BEST FORWARD SPD. WE HAD 100 KT TAILWIND; AND WERE INDICATING 320 KTS. CTLR EVENTUALLY TOLD US START DSCNT; KEEP SPD UP AND GAVE US HDG CHANGE TO POLAR INTXN. A MIN OR SO LATER HE GAVE US A FREQ CHANGE. AT THAT TIME WE WERE OUT OF 17000 FT TO 12000 FT FOR XING POLAR (NO SPD RESTR). WE WERE ABOUT 5 MI FROM POLAR BY OUR CALCULATIONS AND NOT ABLE TO MEET XING ALT AT POLAR INTXN. WITHOUT GPS WE WERE UNABLE TO DETERMINE EXACT LOCATION OF POLAR. UPON INITIAL CONTACT WITH FINAL CTLR (DTW APCH) HE GAVE US A HDG FURTHER R TO INTERCEPT THE DXO 343 DEG RADIAL INSIDE OF POLAR INTXN AND TO DSND AND MAINTAIN 9000 FT. WE FOLLOWED INSTRUCTIONS. AT THIS TIME WE WERE INSIDE THE DXO 41 DME OF POLAR AND JUST INTERCEPTING THE DXO 343 DEG RADIAL OUT OF 15000 FT OR SO; DSNDING TO 12000 FT. THE CTLR DID NOT SAY ANYTHING ABOUT OUR INITIAL CLRNC FROM ZOB TO CROSS POLAR INTXN AT 12000 FT; JUST GAVE US A NEW HDG AND ALT. NO TFC CONFLICT OCCURRED OR TCASII ALERT. NO TFC IN OUR VICINITY. WE SHOULD HAVE NOT ACCEPTED THE DIRECT HDG TO POLAR INTXN AND THE XING WITHOUT GPS DIRECTION OR THE EXACT VECTORING AND RANGING BY ZOB.