 |
37000 Feet | Browse and search NASA's Aviation Safety Reporting System |
|
B757 flight crew began a late descent after ATC queried if they were going to make their crossing restr. The FMC was still showing that the aircraft had not yet reached the top of the descent point. The flight crew descended the aircraft to the crossing altitude 2 mi past the restr. Altitude crossing restr not met.
| Attributes | |
| ACN | 326877 |
| Time | |
| Date | 199601 |
| Day | Tue |
| Local Time Of Day | 1801 To 2400 |
| Place | |
| Locale Reference | atc facility : dta |
| State Reference | UT |
| Altitude | msl bound lower : 31000 msl bound upper : 31000 |
| Environment | |
| Flight Conditions | IMC |
| Light | Night |
| Aircraft 1 | |
| Operator | common carrier : air carrier |
| Make Model Name | B757 Undifferentiated or Other Model |
| 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 : zlc |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain instruction : trainee |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 100 flight time total : 17000 flight time type : 22 |
| ASRS Report | 326877 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer observation : company check pilot oversight : pic |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 210 flight time total : 35000 flight time type : 4500 |
| ASRS Report | 326760 |
| Events | |
| Anomaly | altitude deviation : crossing restriction not met altitude deviation : undershoot non adherence : clearance other anomaly other |
| Independent Detector | other controllera |
| Resolutory Action | flight crew : returned to intended course or assigned course other other |
| Consequence | faa : reviewed incident with flight crew |
| Supplementary | |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | Pilot Deviation |
Narrative:
ZLC told us to cross 10 mi south of dta VOR at 31000 ft. That clearance was loaded into the FMC and VNAV was selected on the MCP, and the flight director and autoplt were engaged. A short time later, center called and asked if we were going to make the restr, we replied that we were and started our descent from 37000 ft even though the computer said we had not yet reached our top of descent point. With the help of the speed brakes we reached 31000 ft 8 mi south of dta. I am a new captain on the B757 and was receiving my IOE from a line check airman who was in command of this flight. We had flown over 8 1/2 hours hard time and had been on duty over 13 1/2 hours when this excursion took place. I don't know if we programmed the FMC wrong, or if we had a computer glitch, or if we were too busy to notice our position (raw data). I am sure fatigue played a role in this case. No other aircraft were in our vicinity. Supplemental information from acn 326760: loaded in 13 mi south (for extra cushion) at FL310. Top of descent from computer gave us approximately 3 mi to lose 6000 ft. Had to use: speed brakes, power off, and maximum operating mach number speeds. Missed by 1 mi -- had faulty equipment. Called ATC upon arrival. First time this has ever happened.
Original NASA ASRS Text
Title: B757 FLC BEGAN A LATE DSCNT AFTER ATC QUERIED IF THEY WERE GOING TO MAKE THEIR XING RESTR. THE FMC WAS STILL SHOWING THAT THE ACFT HAD NOT YET REACHED THE TOP OF THE DSCNT POINT. THE FLC DSNDED THE ACFT TO THE XING ALT 2 MI PAST THE RESTR. ALT XING RESTR NOT MET.
Narrative: ZLC TOLD US TO CROSS 10 MI S OF DTA VOR AT 31000 FT. THAT CLRNC WAS LOADED INTO THE FMC AND VNAV WAS SELECTED ON THE MCP, AND THE FLT DIRECTOR AND AUTOPLT WERE ENGAGED. A SHORT TIME LATER, CTR CALLED AND ASKED IF WE WERE GOING TO MAKE THE RESTR, WE REPLIED THAT WE WERE AND STARTED OUR DSCNT FROM 37000 FT EVEN THOUGH THE COMPUTER SAID WE HAD NOT YET REACHED OUR TOP OF DSCNT POINT. WITH THE HELP OF THE SPD BRAKES WE REACHED 31000 FT 8 MI S OF DTA. I AM A NEW CAPT ON THE B757 AND WAS RECEIVING MY IOE FROM A LINE CHK AIRMAN WHO WAS IN COMMAND OF THIS FLT. WE HAD FLOWN OVER 8 1/2 HRS HARD TIME AND HAD BEEN ON DUTY OVER 13 1/2 HRS WHEN THIS EXCURSION TOOK PLACE. I DON'T KNOW IF WE PROGRAMMED THE FMC WRONG, OR IF WE HAD A COMPUTER GLITCH, OR IF WE WERE TOO BUSY TO NOTICE OUR POS (RAW DATA). I AM SURE FATIGUE PLAYED A ROLE IN THIS CASE. NO OTHER ACFT WERE IN OUR VICINITY. SUPPLEMENTAL INFO FROM ACN 326760: LOADED IN 13 MI S (FOR EXTRA CUSHION) AT FL310. TOP OF DSCNT FROM COMPUTER GAVE US APPROX 3 MI TO LOSE 6000 FT. HAD TO USE: SPD BRAKES, PWR OFF, AND MAX OPERATING MACH NUMBER SPDS. MISSED BY 1 MI -- HAD FAULTY EQUIP. CALLED ATC UPON ARR. FIRST TIME THIS HAS EVER HAPPENED.
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.