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Flight crew of large transport on descent failed to continue descent after making their crossing restriction.
| Attributes | |
| ACN | 112722 |
| Time | |
| Date | 198906 |
| Day | Thu |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | atc facility : hyp |
| State Reference | CA |
| Altitude | msl bound lower : 20000 msl bound upper : 24000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Operator | common carrier : air carrier |
| Make Model Name | Large Transport, Low Wing, 3 Turbojet Eng |
| Flight Phase | descent other |
| Route In Use | enroute airway : zoa |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 90 flight time total : 13000 flight time type : 6000 |
| ASRS Report | 112722 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : atp |
| Events | |
| Anomaly | altitude deviation : undershoot non adherence : clearance other anomaly other |
| Independent Detector | other controllera |
| Resolutory Action | other |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | Pilot Deviation |
Narrative:
Approaching el nido VOR on flight from denver to san jose, first officer flying, received clearance to 'cross el nido VOR at or below FL240, descend and maintain FL200'. First officer crossed el nido at 240 and started very slow drift down to FL200. We were at about 23,800, 10 mi west of el nido when controller asked us to expedite our descent to FL200. Shortly thereafter, another voice came on (probably supervisor) and queried 'did you interpret your clearance to 200 after el nido to be at pilot's discretion?' I answered in the affirmative, and realized at that point that we had both misinterpreted the clearance. I can't explain how I fell into this trap. I am aware of the finer points of 'pilot's discretion' descent clrncs and just wasn't as alert as I should have been. In hindsight, I should have clearly been aware that the descent after el nido was not at pilot's discretion, that the discretionary part applied only to that portion of the descent prior to the altitude restriction at el nido. I am still not sure that the first officer agrees with me, indicating that this is an area of confusion that might be clarified with a bulletin.
Original NASA ASRS Text
Title: FLT CREW OF LGT ON DESCENT FAILED TO CONTINUE DESCENT AFTER MAKING THEIR CROSSING RESTRICTION.
Narrative: APCHING EL NIDO VOR ON FLT FROM DENVER TO SAN JOSE, F/O FLYING, RECEIVED CLRNC TO 'CROSS EL NIDO VOR AT OR BELOW FL240, DSND AND MAINTAIN FL200'. F/O CROSSED EL NIDO AT 240 AND STARTED VERY SLOW DRIFT DOWN TO FL200. WE WERE AT ABOUT 23,800, 10 MI W OF EL NIDO WHEN CTLR ASKED US TO EXPEDITE OUR DSCNT TO FL200. SHORTLY THEREAFTER, ANOTHER VOICE CAME ON (PROBABLY SUPVR) AND QUERIED 'DID YOU INTERPRET YOUR CLRNC TO 200 AFTER EL NIDO TO BE AT PLT'S DISCRETION?' I ANSWERED IN THE AFFIRMATIVE, AND REALIZED AT THAT POINT THAT WE HAD BOTH MISINTERPRETED THE CLRNC. I CAN'T EXPLAIN HOW I FELL INTO THIS TRAP. I AM AWARE OF THE FINER POINTS OF 'PLT'S DISCRETION' DSCNT CLRNCS AND JUST WASN'T AS ALERT AS I SHOULD HAVE BEEN. IN HINDSIGHT, I SHOULD HAVE CLEARLY BEEN AWARE THAT THE DSCNT AFTER EL NIDO WAS NOT AT PLT'S DISCRETION, THAT THE DISCRETIONARY PART APPLIED ONLY TO THAT PORTION OF THE DSCNT PRIOR TO THE ALT RESTRICTION AT EL NIDO. I AM STILL NOT SURE THAT THE F/O AGREES WITH ME, INDICATING THAT THIS IS AN AREA OF CONFUSION THAT MIGHT BE CLARIFIED WITH A BULLETIN.
Data retrieved from NASA's ASRS site as of August 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.