Narrative:

We were filed for the CHPTR2 arrival and just prior to its first point ATC asked if we were able to fly the BNKR2 arrival. We reviewed and discussed the arrival as published; conducted a route check; checked NOTAMS and concluded that we would be able to conduct that arrival. Upon acceptance; we updated the FMC with the BNKR2 and updated the altitude and airspeed constraints as well as the forecast winds for the descent. We made the first point of ponze a hard altitude to enable geopath descent; and were given a speed of 270 knots by ATC prior to bankr. At around contr prior to opals I ascertained that the autopilot VNAV would not be able to meet its restriction at opals and elected to utilize speed brakes and idle descent to increase descent rate. The autopilot upon passing opals then increased its downward pitch to meet the restriction by blnce and increased airspeed to 290 knots. Shortly afterwards; we received a vector from ATC to aid in slowing to the published airspeed. After slowing below 270 knots I elected to utilize the gear to further increase our drag and descent rate to get on profile for the ILS 36L approach. During the approach the controller asked us to contact their supervisor upon landing to discuss this arrival as there were other instances of 737NG's not being able to meet the restrictions. The captain discussed the scenario on the phone after landing via the number provided. After review of the arrival between the points debbt and blnce there is a large amount of altitude to lose in relatively short distance that the VNAV descent could not accomplish or calculate correctly. That in conjunction with a large tail wind further complicates the arrival. The VNAV function in the 737NG has difficulty commanding the aircraft for descent while conducting this arrival which is most evident at points cont to opals. Altering cont or opals to hard altitudes may aid the VNAV in calculating proper descent profiles.

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Original NASA ASRS Text

Title: B737-800 flight crew reported the aircraft was unable to meet the published crossing restrictions.

Narrative: We were filed for the CHPTR2 arrival and just prior to its first point ATC asked if we were able to fly the BNKR2 arrival. We reviewed and discussed the arrival as published; conducted a route check; checked NOTAMS and concluded that we would be able to conduct that arrival. Upon acceptance; we updated the FMC with the BNKR2 and updated the altitude and airspeed constraints as well as the forecast winds for the descent. We made the first point of PONZE a hard altitude to enable geopath descent; and were given a speed of 270 knots by ATC prior to BANKR. At around CONTR prior to OPALS I ascertained that the autopilot VNAV would not be able to meet its restriction at OPALS and elected to utilize speed brakes and idle descent to increase descent rate. The autopilot upon passing OPALS then increased its downward pitch to meet the restriction by BLNCE and increased airspeed to 290 Knots. Shortly afterwards; we received a vector from ATC to aid in slowing to the published airspeed. After slowing below 270 knots I elected to utilize the gear to further increase our drag and descent rate to get on profile for the ILS 36L approach. During the approach the Controller asked us to contact their Supervisor upon landing to discuss this arrival as there were other instances of 737NG's not being able to meet the restrictions. The Captain discussed the scenario on the phone after landing via the number provided. After review of the arrival between the points DEBBT and BLNCE there is a large amount of altitude to lose in relatively short distance that the VNAV descent could not accomplish or calculate correctly. That in conjunction with a large tail wind further complicates the arrival. The VNAV function in the 737NG has difficulty commanding the aircraft for descent while conducting this arrival which is most evident at points CONT to OPALS. Altering CONT or OPALS to hard altitudes may aid the VNAV in calculating proper descent profiles.

Data retrieved from NASA's ASRS site 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.