Narrative:

After departing cvg, we were climbing and cleared to intercept the bluegrass 3 departure, iiu (louisville) transition, on course. Captain was hand flying and I was programming FMS. We were given the clearance 'air carrier XXX, turn right, heading 240 degrees, join the bluegrass 3.' I selected 240 degree heading and the captain turned. The captain had put the BLUEGRASS3.iiu on the FMC prior to departure and when given the clearance to join, iiu was shown on line 1L of the FMC as the active waypoint. The computer showed the course to be 218 degrees direct to iiu and prior to accepting that, I looked at the chart and saw it was a 221 degree radial out of cvg to iiu. I didn't know whether the captain had ever had cvg in the FMS at all or where the 218 degrees came from (sometimes the FMC changes course 1 degree or 2) so reasoning we were close to the cvg VOR, I put in 221 degrees as the 'intercept leg to' course. I looked at the map, confirmed that the course overlaid with the cvg VOR, executed and selected navigation (LNAV). The course was immediately captured. Shortly thereafter, ATC said our heading should be 240 degrees to intercept the course. I said we were on course. She said we were 5 mi east of course. I went back to the chart as the captain flew 240 degrees and put the 216 degree course into iiu, which the captain did not like. He said go direct cvg then remove the discontinuity between cvg and iiu, then direct intercept the leg to iiu (which will work, but is keystroke intense), but I did so and got a 219 degree inbound course to iiu, which we intercepted and nothing more was said. I don't think that there was any loss of separation. Comments: ahars equipped aircraft -- not as accurate as IRS. Captain hand flew throughout this instead of putting autoplt on and helping. I really don't believe a 2 degree error is significant at +/-35 mi from a VOR station. Older aircraft and with no RNAV can't even do that well. I did the math and couldn't get a 5 mi error out of a 2-6 degree error (depending on which FMC course you trust, the one it generated, or my 216 degree course manually inserted, which I trust more).

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Original NASA ASRS Text

Title: B757 CREW DID NOT FLY THE ASSIGNED HDG FOR INTERCEPT OF SID RADIAL.

Narrative: AFTER DEPARTING CVG, WE WERE CLBING AND CLRED TO INTERCEPT THE BLUEGRASS 3 DEP, IIU (LOUISVILLE) TRANSITION, ON COURSE. CAPT WAS HAND FLYING AND I WAS PROGRAMMING FMS. WE WERE GIVEN THE CLRNC 'ACR XXX, TURN R, HDG 240 DEGS, JOIN THE BLUEGRASS 3.' I SELECTED 240 DEG HDG AND THE CAPT TURNED. THE CAPT HAD PUT THE BLUEGRASS3.IIU ON THE FMC PRIOR TO DEP AND WHEN GIVEN THE CLRNC TO JOIN, IIU WAS SHOWN ON LINE 1L OF THE FMC AS THE ACTIVE WAYPOINT. THE COMPUTER SHOWED THE COURSE TO BE 218 DEGS DIRECT TO IIU AND PRIOR TO ACCEPTING THAT, I LOOKED AT THE CHART AND SAW IT WAS A 221 DEG RADIAL OUT OF CVG TO IIU. I DIDN'T KNOW WHETHER THE CAPT HAD EVER HAD CVG IN THE FMS AT ALL OR WHERE THE 218 DEGS CAME FROM (SOMETIMES THE FMC CHANGES COURSE 1 DEG OR 2) SO REASONING WE WERE CLOSE TO THE CVG VOR, I PUT IN 221 DEGS AS THE 'INTERCEPT LEG TO' COURSE. I LOOKED AT THE MAP, CONFIRMED THAT THE COURSE OVERLAID WITH THE CVG VOR, EXECUTED AND SELECTED NAV (LNAV). THE COURSE WAS IMMEDIATELY CAPTURED. SHORTLY THEREAFTER, ATC SAID OUR HDG SHOULD BE 240 DEGS TO INTERCEPT THE COURSE. I SAID WE WERE ON COURSE. SHE SAID WE WERE 5 MI E OF COURSE. I WENT BACK TO THE CHART AS THE CAPT FLEW 240 DEGS AND PUT THE 216 DEG COURSE INTO IIU, WHICH THE CAPT DID NOT LIKE. HE SAID GO DIRECT CVG THEN REMOVE THE DISCONTINUITY BTWN CVG AND IIU, THEN DIRECT INTERCEPT THE LEG TO IIU (WHICH WILL WORK, BUT IS KEYSTROKE INTENSE), BUT I DID SO AND GOT A 219 DEG INBOUND COURSE TO IIU, WHICH WE INTERCEPTED AND NOTHING MORE WAS SAID. I DON'T THINK THAT THERE WAS ANY LOSS OF SEPARATION. COMMENTS: AHARS EQUIPPED ACFT -- NOT AS ACCURATE AS IRS. CAPT HAND FLEW THROUGHOUT THIS INSTEAD OF PUTTING AUTOPLT ON AND HELPING. I REALLY DON'T BELIEVE A 2 DEG ERROR IS SIGNIFICANT AT +/-35 MI FROM A VOR STATION. OLDER ACFT AND WITH NO RNAV CAN'T EVEN DO THAT WELL. I DID THE MATH AND COULDN'T GET A 5 MI ERROR OUT OF A 2-6 DEG ERROR (DEPENDING ON WHICH FMC COURSE YOU TRUST, THE ONE IT GENERATED, OR MY 216 DEG COURSE MANUALLY INSERTED, WHICH I TRUST MORE).

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.