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B737 captain reports missing crossing restrictions during the kepec arrival to las after selecting altitude intv to smooth the descent.
| Attributes | |
| ACN | 843399 |
| Time | |
| Date | 200907 |
| Local Time Of Day | 0601-1200 |
| Place | |
| Locale Reference | L30.TRACON |
| State Reference | NV |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Make Model Name | B737-700 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Descent |
| Route In Use | STAR KEPEC |
| Flight Plan | IFR |
| Component | |
| Aircraft Component | FMS/FMC |
| Person 1 | |
| Function | Captain |
| Experience | Flight Crew Last 90 Days 244 |
| Person 2 | |
| Function | Pilot Not Flying First Officer |
| Experience | Flight Crew Last 90 Days 271 |
| Events | |
| Anomaly | Deviation - Altitude Crossing Restriction Not Met Deviation - Procedural Clearance Deviation - Procedural Published Material / Policy |
Narrative:
On kepec arrival into las FL280; cleared to 'descend via the kepec arrival. MCP altitude set to 8000 ft (lowest altitude on arrival). VNAV and autothrottles were engaged as well as LNAV. Aircraft followed VNAV path to cross misen at FL240. Pushed altitude intv button for smooth descent to cross the remainder of fixes. Aircraft descended 200-300 ft and then climbed back up to FL240 and leveled off. Pushed altitude intv again and aircraft descended and climbed as before. Second push of altitude intv apparently deleted the altitude restriction at clarr and I did not catch it. Aircraft began VNAV path descent for kepec at 12;000 ft. Missed clarr altitude by approximately 2500 ft. Descended rapidly to attain appropriate flight path but then descended 500' below next altitude constraint of 12;000 ft. Informed ATC we were high at clarr but were correcting and ATC said; 'thanks.' elected not to use VNAV for remainder of arrival. All systems were working well on aircraft. I 'won't use the altitude intv or speed intv buttons ever again.'
Original NASA ASRS Text
Title: B737 Captain reports missing crossing restrictions during the KEPEC arrival to LAS after selecting ALT INTV to smooth the descent.
Narrative: On KEPEC Arrival into LAS FL280; cleared to 'descend via the KEPEC Arrival. MCP altitude set to 8000 FT (lowest altitude on arrival). VNAV and autothrottles were engaged as well as LNAV. Aircraft followed VNAV PATH to cross MISEN at FL240. Pushed ALT INTV button for smooth descent to cross the remainder of fixes. Aircraft descended 200-300 FT and then climbed back up to FL240 and leveled off. Pushed ALT INTV again and aircraft descended and climbed as before. Second push of ALT INTV apparently deleted the altitude restriction at CLARR and I did not catch it. Aircraft began VNAV PATH descent for KEPEC at 12;000 FT. Missed CLARR altitude by approximately 2500 FT. Descended rapidly to attain appropriate flight path but then descended 500' below next altitude constraint of 12;000 FT. Informed ATC we were high at CLARR but were correcting and ATC said; 'thanks.' Elected not to use VNAV for remainder of arrival. All systems were working well on aircraft. I 'Won't use the ALT INTV or SPD INTV buttons ever again.'
Data retrieved from NASA's ASRS site as of April 2012 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.