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An A321 type air carrier flight crew misjudged the start of descent and crossed their fix above the assigned altitude 40 mi west of csn, va.
| Attributes | |
| ACN | 486429 |
| Time | |
| Date | 200009 |
| Day | Sat |
| Local Time Of Day | 1801 To 2400 |
| Place | |
| Locale Reference | navaid : csn.vortac |
| State Reference | VA |
| Altitude | msl bound lower : 27000 msl bound upper : 35000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Night |
| Aircraft 1 | |
| Controlling Facilities | artcc : zdc.artcc |
| Operator | common carrier : air carrier |
| Make Model Name | Airbus Industrie Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | other other vortac |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp pilot : cfi pilot : flight engineer |
| Experience | flight time last 90 days : 170 flight time total : 10000 flight time type : 720 |
| ASRS Report | 486429 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : multi engine pilot : commercial pilot : instrument |
| Events | |
| Anomaly | altitude deviation : undershoot altitude deviation : crossing restriction not met non adherence : clearance other anomaly other |
| Resolutory Action | controller : issued new clearance controller : separated traffic other |
| Consequence | faa : reviewed incident with flight crew |
| Supplementary | |
| Problem Areas | Weather Flight Crew Human Performance Environmental Factor Airspace Structure Aircraft |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | Pilot Deviation |
Narrative:
At cruise altitude into bwi, we received clearance to cross 40 NM west of csn at or below FL270. We both calculated top of descent and verbalized it. (Later, I realized we were both in error.) at the time, we were discussing bwi WX which was runway 10 RVR 1800 ft in fog, visibility 2400 ft. A CAT III autoland was evident and we were reviewing the procedure orally. Then we got clearance to cross 40 mi west of csn at or below FL270 and continue to cross csn at FL190. At that time we realized we were very high and should have started down about 20 mi back. I told the controller we would be high 40 NM west of csn and he turned us left 30 degrees for traffic. The xyz FMC cannot create a waypoint and plot a constraint on the navigation display like the abc FMS can. There is more mental arithmetic and constant re-evaluation to staying on the vertical profile. We were preoccupied with deterioration of bwi WX and miscalculated top of descent.
Original NASA ASRS Text
Title: AN A321 TYPE ACR FLC MISJUDGED THE START OF DSCNT AND CROSSED THEIR FIX ABOVE THE ASSIGNED ALT 40 MI W OF CSN, VA.
Narrative: AT CRUISE ALT INTO BWI, WE RECEIVED CLRNC TO CROSS 40 NM W OF CSN AT OR BELOW FL270. WE BOTH CALCULATED TOP OF DSCNT AND VERBALIZED IT. (LATER, I REALIZED WE WERE BOTH IN ERROR.) AT THE TIME, WE WERE DISCUSSING BWI WX WHICH WAS RWY 10 RVR 1800 FT IN FOG, VISIBILITY 2400 FT. A CAT III AUTOLAND WAS EVIDENT AND WE WERE REVIEWING THE PROC ORALLY. THEN WE GOT CLRNC TO CROSS 40 MI W OF CSN AT OR BELOW FL270 AND CONTINUE TO CROSS CSN AT FL190. AT THAT TIME WE REALIZED WE WERE VERY HIGH AND SHOULD HAVE STARTED DOWN ABOUT 20 MI BACK. I TOLD THE CTLR WE WOULD BE HIGH 40 NM W OF CSN AND HE TURNED US L 30 DEGS FOR TFC. THE XYZ FMC CANNOT CREATE A WAYPOINT AND PLOT A CONSTRAINT ON THE NAV DISPLAY LIKE THE ABC FMS CAN. THERE IS MORE MENTAL ARITHMETIC AND CONSTANT RE-EVALUATION TO STAYING ON THE VERT PROFILE. WE WERE PREOCCUPIED WITH DETERIORATION OF BWI WX AND MISCALCULATED TOP OF DSCNT.
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.