Narrative:

With ZOB on arrival descent (polar 1) from ord to dtw. Initially cleared direct fnt, then given heading to direct polar +/-3 mi either side of polar intersection (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 intersection at 12000 ft. Also, ZOB told us best forward speed. We had 100 KT tailwind, and were indicating 320 KTS. Controller eventually told us start descent, keep speed up and gave us heading change to polar intersection. A min or so later he gave us a frequency change. At that time we were out of 17000 ft to 12000 ft for crossing polar (no speed restr). We were about 5 mi from polar by our calculations and not able to meet crossing altitude at polar intersection. Without GPS we were unable to determine exact location of polar. Upon initial contact with final controller (dtw approach) he gave us a heading further right to intercept the dxo 343 degree radial inside of polar intersection and to descend 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 degree radial out of 15000 ft or so, descending to 12000 ft. The controller did not say anything about our initial clearance from ZOB to cross polar intersection at 12000 ft, just gave us a new heading and altitude. No traffic conflict occurred or TCASII alert. No traffic in our vicinity. We should have not accepted the direct heading to polar intersection and the crossing without GPS direction or the exact vectoring and ranging by ZOB.

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Original NASA ASRS Text

Title: 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.

Data retrieved from NASA's ASRS site as of July 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.