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B737-700 first officer as the pilot monitoring noted that the aircraft had reverted from VNAV path to VNAV speed while descending to make a crossing restriction. The captain attempted to use vertical speed and the speed brake to make the restriction with the autopilot engaged; but altitude acquire occurs a 1;000 feet above and the fix is crossed 400 feet high.
| Attributes | |
| ACN | 1352275 |
| Time | |
| Date | 201605 |
| Place | |
| Locale Reference | ZMP.ARTCC |
| State Reference | MN |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Make Model Name | B737-700 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Descent |
| Flight Plan | IFR |
| Component | |
| Aircraft Component | FMS/FMC |
| Person 1 | |
| Function | First Officer Pilot Not Flying |
| Qualification | Flight Crew Air Transport Pilot (ATP) |
| Experience | Flight Crew Last 90 Days 181 Flight Crew Type 6000 |
| Events | |
| Anomaly | Aircraft Equipment Problem Less Severe Deviation - Altitude Crossing Restriction Not Met Deviation - Altitude Undershoot Deviation - Procedural Clearance Deviation - Procedural Published Material / Policy |
Narrative:
We were level at 39;000 feet and given a crossing restriction of ohhmy at 31;000 feet. The FMC was programmed correctly and VNAV engaged. During the descent; the aircraft reverted from VNAV path to VNAV speed. I called out the deviation to the pilot flying (PF). He selected vertical speed mode and extended the speedbrakes. We still had time to make the cross. But the vertical speed selected was not enough. I pointed out we were still going to be high; and the PF increased the descent rate selected. But then as we were catching up the aircraft entered 'altitude acq' around 1000 feet above our altitude and slowed its descent much more than typical for this situation almost leveling 600 feet high. I again pointed out we were going to be high in this configuration but the PF chose to keep the autopilot engaged. We were around 400 feet high. When this happens a more immediate and adequate response needs to be initiated keeping in mind the time required to level off.
Original NASA ASRS Text
Title: B737-700 First Officer as the Pilot Monitoring noted that the aircraft had reverted from VNAV PATH to VNAV SPEED while descending to make a crossing restriction. The Captain attempted to use vertical speed and the speed brake to make the restriction with the autopilot engaged; but Altitude Acquire occurs a 1;000 feet above and the fix is crossed 400 feet high.
Narrative: We were level at 39;000 feet and given a crossing restriction of OHHMY at 31;000 feet. The FMC was programmed correctly and VNAV engaged. During the descent; the aircraft reverted from VNAV PATH to VNAV SPEED. I called out the deviation to the Pilot Flying (PF). He selected Vertical Speed mode and extended the speedbrakes. We still had time to make the cross. But the Vertical Speed selected was not enough. I pointed out we were still going to be high; and the PF increased the descent rate selected. But then as we were catching up the aircraft entered 'ALT ACQ' around 1000 feet above our altitude and slowed its descent much more than typical for this situation almost leveling 600 feet high. I again pointed out we were going to be high in this configuration but the PF chose to keep the autopilot engaged. We were around 400 feet high. When this happens a more immediate and adequate response needs to be initiated keeping in mind the time required to level off.
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.