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A B757-200 crosses pom, ca, 1000 ft above published altitude because the automatic flight controls were in VNAV.
| Attributes | |
| ACN | 385079 |
| Time | |
| Date | 199711 |
| Day | Fri |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | atc facility : pom airport : ont |
| State Reference | CA |
| Altitude | msl bound lower : 8000 msl bound upper : 9000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | tracon : ont |
| Operator | common carrier : air carrier |
| Make Model Name | B757-200 |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | Other Other |
| Flight Phase | climbout : intermediate altitude |
| Route In Use | departure other departure sid : sid |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 200 flight time total : 12000 flight time type : 1800 |
| ASRS Report | 385079 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : commercial pilot : flight engineer pilot : atp |
| Experience | flight time last 90 days : 180 flight time total : 5000 flight time type : 1000 |
| ASRS Report | 385080 |
| Events | |
| Anomaly | altitude deviation : crossing restriction not met non adherence : published procedure non adherence : clearance |
| Independent Detector | atc equipment other atc equipment : unspecified other controllera |
| Resolutory Action | none taken : detected after the fact |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | Pilot Deviation |
Narrative:
On departure on pomona 6 SID with an 8000 ft at or below restr at pomona we were using LNAV and VNAV. The controller questioned our altitude which was 9000 ft and said we had a restr of 8000 ft. Our LNAV was at that time directing a turn toward dag 227 degree radial having dropped the last waypoint pomona and allowing us to climb to our next altitude. That was a normal LNAV, VNAV situation. If this departure does take into account the normal LNAV, VNAV operation it needs to be changed to allow for how these functions operate. In other words our navigation system showed us past the restrictive fix and allowed us to climb to our next altitude. Supplemental information from acn 385080: ATC controller advised us of altitude deviation during pomona six departure from ontario airport. There is an altitude crossing restr at pomona VOR at or below 8000 ft. Our navigation system showed us at VOR and turning to next waypoint. We continued climb to 14000 ft assigned. ATC controller advised us that we were higher than 8000 ft at pomona. Our climb rate was 3000 FPM. Our FMC was in vertical navigation mode and lateral navigation mode. When we arrive at waypoint, the waypoint changes distance and time in zulu of next waypoint. This had happened when controller advised us of over pomona VOR.
Original NASA ASRS Text
Title: A B757-200 CROSSES POM, CA, 1000 FT ABOVE PUBLISHED ALT BECAUSE THE AUTOMATIC FLT CTLS WERE IN VNAV.
Narrative: ON DEP ON POMONA 6 SID WITH AN 8000 FT AT OR BELOW RESTR AT POMONA WE WERE USING LNAV AND VNAV. THE CTLR QUESTIONED OUR ALT WHICH WAS 9000 FT AND SAID WE HAD A RESTR OF 8000 FT. OUR LNAV WAS AT THAT TIME DIRECTING A TURN TOWARD DAG 227 DEG RADIAL HAVING DROPPED THE LAST WAYPOINT POMONA AND ALLOWING US TO CLB TO OUR NEXT ALT. THAT WAS A NORMAL LNAV, VNAV SIT. IF THIS DEP DOES TAKE INTO ACCOUNT THE NORMAL LNAV, VNAV OP IT NEEDS TO BE CHANGED TO ALLOW FOR HOW THESE FUNCTIONS OPERATE. IN OTHER WORDS OUR NAV SYS SHOWED US PAST THE RESTRICTIVE FIX AND ALLOWED US TO CLB TO OUR NEXT ALT. SUPPLEMENTAL INFO FROM ACN 385080: ATC CTLR ADVISED US OF ALTDEV DURING POMONA SIX DEP FROM ONTARIO ARPT. THERE IS AN ALT XING RESTR AT POMONA VOR AT OR BELOW 8000 FT. OUR NAV SYS SHOWED US AT VOR AND TURNING TO NEXT WAYPOINT. WE CONTINUED CLB TO 14000 FT ASSIGNED. ATC CTLR ADVISED US THAT WE WERE HIGHER THAN 8000 FT AT POMONA. OUR CLB RATE WAS 3000 FPM. OUR FMC WAS IN VERT NAV MODE AND LATERAL NAV MODE. WHEN WE ARRIVE AT WAYPOINT, THE WAYPOINT CHANGES DISTANCE AND TIME IN ZULU OF NEXT WAYPOINT. THIS HAD HAPPENED WHEN CTLR ADVISED US OF OVER POMONA VOR.
Data retrieved from NASA's ASRS site as of July 2007 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.