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Flight crew of an medium large transport failed to make their crossing descent altitude due to misinterp of the route chart distance information.
| Attributes | |
| ACN | 313990 |
| Time | |
| Date | 199508 |
| Day | Mon |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | atc facility : hec airport : ont |
| State Reference | CA |
| Altitude | msl bound lower : 12000 msl bound upper : 14100 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Operator | common carrier : air carrier |
| Make Model Name | B737-300 |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | Other Other |
| Flight Phase | descent other |
| Route In Use | arrival other arrival star : star enroute airway : zla |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | other other : other pilot : commercial pilot : flight engineer pilot : instrument |
| Experience | flight time last 90 days : 240 flight time total : 3875 flight time type : 3000 |
| ASRS Report | 313990 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Events | |
| Anomaly | altitude deviation : crossing restriction not met altitude deviation : undershoot non adherence : clearance non adherence : published procedure other anomaly |
| Independent Detector | other controllera |
| Resolutory Action | other |
| Consequence | faa : reviewed incident with flight crew |
| Supplementary | |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | Pilot Deviation |
Narrative:
We took the airplane fmcs inoperative which is very non standard. We were filed for ziggy 3. We each calculated start down point independently. When I reviewed the ziggy 3 I made the mistake of adding the distances on the switch over point as the distance between hector and dawna, when the actual distance was only 46 mi. The controller came on and told us to start our descent at which point we began a full descent. We were supposed to cross dawna at 12000 ft and 250 KTS. We crossed it at 14000 mi plus a little bit and 300 KTS. The controller switched us to socal approach who gave us a turn so we could get down enough to start approach. On discussion with captain, he had made same mistake as I. One factor contributing is due to infrequent use of the switch over points and leg length information on this chart. We were not as familiar with this information and what it meant as we should have been. Normally all leg lengths are in the FMC.
Original NASA ASRS Text
Title: FLC OF AN MLG FAILED TO MAKE THEIR XING DSCNT ALT DUE TO MISINTERP OF THE RTE CHART DISTANCE INFO.
Narrative: WE TOOK THE AIRPLANE FMCS INOP WHICH IS VERY NON STANDARD. WE WERE FILED FOR ZIGGY 3. WE EACH CALCULATED START DOWN POINT INDEPENDENTLY. WHEN I REVIEWED THE ZIGGY 3 I MADE THE MISTAKE OF ADDING THE DISTANCES ON THE SWITCH OVER POINT AS THE DISTANCE BTWN HECTOR AND DAWNA, WHEN THE ACTUAL DISTANCE WAS ONLY 46 MI. THE CTLR CAME ON AND TOLD US TO START OUR DSCNT AT WHICH POINT WE BEGAN A FULL DSCNT. WE WERE SUPPOSED TO CROSS DAWNA AT 12000 FT AND 250 KTS. WE CROSSED IT AT 14000 MI PLUS A LITTLE BIT AND 300 KTS. THE CTLR SWITCHED US TO SOCAL APCH WHO GAVE US A TURN SO WE COULD GET DOWN ENOUGH TO START APCH. ON DISCUSSION WITH CAPT, HE HAD MADE SAME MISTAKE AS I. ONE FACTOR CONTRIBUTING IS DUE TO INFREQUENT USE OF THE SWITCH OVER POINTS AND LEG LENGTH INFO ON THIS CHART. WE WERE NOT AS FAMILIAR WITH THIS INFO AND WHAT IT MEANT AS WE SHOULD HAVE BEEN. NORMALLY ALL LEG LENGTHS ARE IN THE FMC.
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.