Date: 201401
Local time of day: 0601-1200
Location: D01.TRACON, CO
Flight conditions: VMC
Light: Daylight
Aircraft: B737 Next Generation Undifferentiated
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Final Approach
Airspace: Class B DEN
ATC / advisory: TRACON D01
Aircraft component: FMS/FMC
Component problem: Design; Improperly Operated
Reporter organization: Air Carrier
Reporter function: Pilot Not Flying; Captain
Human factors: Workload; Situational Awareness
Second reporter function: First Officer; Pilot Flying
Anomaly: ATC Issue All Types; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Clearance; Inflight Event / Encounter Weather / Turbulence
Detector: Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Issued New Clearance; Flight Crew Returned To Clearance; Flight Crew Became Reoriented
Contributing factors: Human Factors; Procedure
Primary problem: Human Factors

Narrative: The Captain was pilot not flying and the First Officer was the pilot flying to DEN. The flight time was 1:22 with light to moderate turbulence and mountain wave during the descent into Denver. The First Officer is on high minimums. I believe he did not have a lot of experience using FMC in complex arrival settings. The Captain was new to the seat. During a short time we had 3 runway changes; 2 SID transition changes and numerous airspeed and altitude changes that did correspond with the airspeed and altitudes and the actual MOLTN 2 arrival. The 3rd runway change was the RNAV Z (RNP) 34R. The weather was clear and this was our 3rd flight together. The CRM setting was above average between the two crew members. The airplane has speed and altitude intervention.  The error occurred on the MOLTN 2 arrival. We had the arrival programmed with no transition in place since we were given [Runway] 35L. About 10 miles from HIMOM ATC changed to RNAV 34R. The pilot flying was looking for charts and pilot not flying was watching airplane. We were then given the clearance cleared RNAV Z 34R HIMOM transition. The pilot flying came back and programmed the FMC and when he moved HIMOM up he put HIMOM on top of HIMOM when there is a discontinuity and I verified and he executed. Since we didn't put HIMOM in the discontinuity boxes it defaulted to the previous route. The error occurred when the pilot not flying was running the Approach Checklist running through the RNP procedures and didn't monitor. We flew past HIMOM to KALME instead of turning on the transition. ATC asked if we had field in sight and cleared us for visual approach. We landed uneventfully and there was no traffic conflict. I debriefed the First Officer on the FMC issues and my failure as a Captain to let him get overwhelmed by the ever changing clearances. I wanted him to get experience programming and changing the box instead having him fly the aircraft and the pilot not flying help out with more of the duties.

Callback: The reporter stated that because the FMS arrival programming was complete for the MOLTN TWO RNAV with the Runway 34L ILS the aircraft was supposed to fly HIMOM; KALME; WASKL then a heading for vectors to the ILS. When ATC changed to approach to the RNAV (RNP) Z RWY 34R; the FMS reloaded the entire MOLTN TWO RNAV and the FMS alerted using RSVR FUEL because of the added distance it had calculated. If left alone the aircraft would fly back to the MOLTN waypoint and re-fly the entire arrival. The end result was the First Officer had to go back and delete all of the waypoints up to HIMOM and then close the Route Discontinuity between HIMOM on the STAR and HIMOM on the RNAV Z approach. Essentially two MOLTN TWO Stars were in the FMS. In this case the aircraft continued to KALME because the FMS could not be programmed quickly enough to fly the clearance. The reporter commented that ATC should understand that when a runway and/or approach change is given the flight crew needs several minutes of FMS programming work before the aircraft is capable of flying an approach utilizing automation. In addition; the programming for an RNAV (RNP) approach requires disabling DME;DME updating and setting the RNP parameters in the FMS. That takes additional time because the correct FMS pages first have to be located; then the data entered. It would best if ATC could make no runway/approach changes late in the arrival sequence or if a change is necessary put the aircraft on a heading; so the crew can go heads down to make the necessary changes.

Second narrative: During preflight; DEN ATIS reported arrival Runways 16R; and I believe 17L and R. Flight plan had us arriving from West; so we selected 16R. I pulled out all three approach plates to south-landing runways. Approaching Top of Descent; the winds changed and so did the runways. Our runway was now changed to 34L. Fine; winds change; runway did too. After I pulled out the ILS plates to all north-landing runways; we reloaded the arrival runway; checked the arrival routing; altitude/speed restrictions; approach routing and altitudes then briefed the approach. Descending thru about 19K; (DEN at 5;350ish); ATC told us to expect landing on Runway 35R. Again we changed runways in the box; checked the box; briefed the approach. Shortly there after; ATC changed landing runway back to 34L and issued clearance for RNAV approach. I had 6 approach plates out by now and this wasn't one of them. We were in IMC; in typical DEN turbulence and ensuring RNAV approach procedures in QRH were complied with. We broke out at about 9-10K. It was clear below and we were then offered and cleared for a visual approach to Runway 34L. Being cleared for visual approach indicates to me that congestion was minimal. While there may have been extenuating ATC circumstances that we were unaware of; I heard no mention of emergencies on the frequency; Controller didn't sound like congestion was an issue; it appeared to me that unnecessary indecisiveness in runway selection was the culprit in this situation.


Synopsis: B737NG flight crew arriving DEN report a track deviation due to multiple ATC adjustments during the arrival; transition changes and three runway changes. The HIMON transition to the RNAV Z 34L is not correctly entered in the FMC and when detected by ATC; the crew is offered a visual approach.