Narrative:

We were on the sketr 1 arrival to msp. For landing on runways 30L/right there is a 105 degree heading after the fcm VOR which is not preloaded in the FMC. When I added a waypoint 10 mi from fcm on a 105 degree heading, I apparently dropped the fcm waypoint. Consequently, after passing futon, the aircraft took up a heading for the fcm 105 degree bearing, 10 DME out. This happened as the captain was briefing the approach so it went unnoticed for several mins until approach control called us with a vector to get 'back on the arrival.' my initial mistake was made mostly because fcm and the new waypoint 'fcm 01' were on 2 different display pages so I couldn't view them simultaneously before executing. My other mistake was not having the captain verify the additional waypoint which is normal operating procedure. I think I felt it was an additional 'extra' waypoint so I could just enter it and not 'bother' him. 2 lessons learned by me. Supplemental information from acn 426827: what probably happened is that as the PNF entered the fix (FCM1) a route discontinuity would have been generated, because some of the fixes were on another page. Some confusion was experienced when closing route discontinuity over 2 pages. I, the PF, never checked the work until we were already headed off course as I was busy setting up the approach and flying the aircraft. We got busy and didn't follow our normal procedures which would have alleviated this problem.

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Original NASA ASRS Text

Title: A B757 FLC ALLOWS THEIR ACFT TO MAKE A PREMATURE TURN OFF THE ARR RTE INTO MSP. FMC PROGRAMMING PROB.

Narrative: WE WERE ON THE SKETR 1 ARR TO MSP. FOR LNDG ON RWYS 30L/R THERE IS A 105 DEG HDG AFTER THE FCM VOR WHICH IS NOT PRELOADED IN THE FMC. WHEN I ADDED A WAYPOINT 10 MI FROM FCM ON A 105 DEG HDG, I APPARENTLY DROPPED THE FCM WAYPOINT. CONSEQUENTLY, AFTER PASSING FUTON, THE ACFT TOOK UP A HDG FOR THE FCM 105 DEG BEARING, 10 DME OUT. THIS HAPPENED AS THE CAPT WAS BRIEFING THE APCH SO IT WENT UNNOTICED FOR SEVERAL MINS UNTIL APCH CTL CALLED US WITH A VECTOR TO GET 'BACK ON THE ARR.' MY INITIAL MISTAKE WAS MADE MOSTLY BECAUSE FCM AND THE NEW WAYPOINT 'FCM 01' WERE ON 2 DIFFERENT DISPLAY PAGES SO I COULDN'T VIEW THEM SIMULTANEOUSLY BEFORE EXECUTING. MY OTHER MISTAKE WAS NOT HAVING THE CAPT VERIFY THE ADDITIONAL WAYPOINT WHICH IS NORMAL OPERATING PROC. I THINK I FELT IT WAS AN ADDITIONAL 'EXTRA' WAYPOINT SO I COULD JUST ENTER IT AND NOT 'BOTHER' HIM. 2 LESSONS LEARNED BY ME. SUPPLEMENTAL INFO FROM ACN 426827: WHAT PROBABLY HAPPENED IS THAT AS THE PNF ENTERED THE FIX (FCM1) A RTE DISCONTINUITY WOULD HAVE BEEN GENERATED, BECAUSE SOME OF THE FIXES WERE ON ANOTHER PAGE. SOME CONFUSION WAS EXPERIENCED WHEN CLOSING RTE DISCONTINUITY OVER 2 PAGES. I, THE PF, NEVER CHKED THE WORK UNTIL WE WERE ALREADY HEADED OFF COURSE AS I WAS BUSY SETTING UP THE APCH AND FLYING THE ACFT. WE GOT BUSY AND DIDN'T FOLLOW OUR NORMAL PROCS WHICH WOULD HAVE ALLEVIATED THIS PROB.

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.