Flight Crew Air Transport Pilot (ATP)
Aircraft Equipment Problem Less Severe
Flight Crew Overcame Equipment Problem; Flight Crew Returned To Clearance
Aircraft; Procedure
We were descending on the HAWKZ 4 arrival approaching PIKEZ intersection when we received a runway change from ATC to 16C. The first officer selected 16c in the FMS; which caused a disconnect on the legs page and took the autopilot out of LNAV just as the aircraft was just about to make the turn from PIKEZ to COFAY . I heading selected the aircraft to the right toward COFAY while the first officer fixed the disconnect in about 2 seconds. LNAV was reengaged. The aircraft was never off course and the ATC controller did not say anything. The point of this report is that this is a common occurrence with the FMC when a runway change is made during the middle of the arrival. The fixes seem to double up; in this case PIKEZ was at the top of the legs page followed by a disconnect and then below that PIKEZ intersection was there again below the disconnect. I don't know if it is a software problem or what but it occurs often with a runway change.
B737-900 Captain describes the FMC's reaction to a runway change entered during an RNAV arrival. A route discontinuity is created and the autopilot reverts to heading hold.