Narrative:

We were flying the bonham five arrival to dfw. We were just past covie about 23 NM past byp and about to level at 11000 ft MSL. We were told to expect runway 35L which was a different runway than briefed and loaded in the FMS. The first officer had gotten the new approach plate out and was hard tuning the new frequency in the FMS. I changed the runway to runway 35L in the FMS; to get the change started. I activated the change and looked down momentarily to get the new approach plate out. When I looked up; I saw the aircraft turning to the right. I immediately disconnected the autoplt and started a turn back to the arrival course. Shortly after starting the turn back; ATC asked if we had started a turn. We replied yes and that we were turning back to the arrival course. By this time I had leveled off at 11000 ft MSL. ATC gave us a 170 degree heading to reintercept the arrival course and to confirm that 11000 ft was assigned. We confirmed the clearance. I established the heading and altitude then engaged the autoplt to join the arrival. As I was doing this I asked the first officer to delete the waypoints that were added by changing the runway after flying part of the arrival (this is a problem at dfw). We briefed the new approach and continued the original arrival. No other comments were made by ATC. The rest of the arrival and approach into dfw were without incident. Note: changing the FMS runway after starting the arrival at dfw loads the entire arrival again. This is not the normal FMS action. The FMS was sending the aircraft back to beginning of the original arrival. I should have confirmed before activating.

Related reports:

Google
 

Original NASA ASRS Text

Title: EMB170 GOES OFF COURSE ON BONHAM 5 ARR TO DFW.

Narrative: WE WERE FLYING THE BONHAM FIVE ARR TO DFW. WE WERE JUST PAST COVIE ABOUT 23 NM PAST BYP AND ABOUT TO LEVEL AT 11000 FT MSL. WE WERE TOLD TO EXPECT RWY 35L WHICH WAS A DIFFERENT RWY THAN BRIEFED AND LOADED IN THE FMS. THE FO HAD GOTTEN THE NEW APCH PLATE OUT AND WAS HARD TUNING THE NEW FREQ IN THE FMS. I CHANGED THE RWY TO RWY 35L IN THE FMS; TO GET THE CHANGE STARTED. I ACTIVATED THE CHANGE AND LOOKED DOWN MOMENTARILY TO GET THE NEW APCH PLATE OUT. WHEN I LOOKED UP; I SAW THE ACFT TURNING TO THE R. I IMMEDIATELY DISCONNECTED THE AUTOPLT AND STARTED A TURN BACK TO THE ARR COURSE. SHORTLY AFTER STARTING THE TURN BACK; ATC ASKED IF WE HAD STARTED A TURN. WE REPLIED YES AND THAT WE WERE TURNING BACK TO THE ARR COURSE. BY THIS TIME I HAD LEVELED OFF AT 11000 FT MSL. ATC GAVE US A 170 DEG HDG TO REINTERCEPT THE ARR COURSE AND TO CONFIRM THAT 11000 FT WAS ASSIGNED. WE CONFIRMED THE CLRNC. I ESTABLISHED THE HDG AND ALT THEN ENGAGED THE AUTOPLT TO JOIN THE ARR. AS I WAS DOING THIS I ASKED THE FO TO DELETE THE WAYPOINTS THAT WERE ADDED BY CHANGING THE RWY AFTER FLYING PART OF THE ARR (THIS IS A PROB AT DFW). WE BRIEFED THE NEW APCH AND CONTINUED THE ORIGINAL ARR. NO OTHER COMMENTS WERE MADE BY ATC. THE REST OF THE ARR AND APCH INTO DFW WERE WITHOUT INCIDENT. NOTE: CHANGING THE FMS RWY AFTER STARTING THE ARR AT DFW LOADS THE ENTIRE ARR AGAIN. THIS IS NOT THE NORMAL FMS ACTION. THE FMS WAS SENDING THE ACFT BACK TO BEGINNING OF THE ORIGINAL ARR. I SHOULD HAVE CONFIRMED BEFORE ACTIVATING.

Data retrieved from NASA's ASRS site as of January 2009 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.