 |
37000 Feet | Browse and search NASA's Aviation Safety Reporting System |
|
Flight crew of a B737-500 believed that they were cleared to a lower en route altitude and started descending. However, after querying the ARTCC controller, he had not intended them to descend until instructed to do so.
| Attributes | |
| ACN | 441721 |
| Time | |
| Date | 199906 |
| Day | Wed |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | navaid : eld.vortac |
| State Reference | AR |
| Altitude | msl bound lower : 32500 msl bound upper : 33000 |
| Environment | |
| Flight Conditions | Mixed |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zfw.artcc |
| Operator | common carrier : air carrier |
| Make Model Name | B737-500 |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | other |
| Route In Use | enroute airway : j29.airway |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 25 flight time total : 5000 flight time type : 12 |
| ASRS Report | 441721 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp pilot : cfi |
| Experience | flight time last 90 days : 190 flight time total : 15000 flight time type : 8000 |
| ASRS Report | 441600 |
| Events | |
| Anomaly | altitude deviation : excursion from assigned altitude non adherence : clearance non adherence other |
| Independent Detector | other controllera |
| Resolutory Action | flight crew : returned to assigned altitude |
| Consequence | Other |
| Supplementary | |
| Problem Areas | ATC Human Performance Flight Crew Human Performance |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | Pilot Deviation |
Narrative:
During cruise at FL330 in our B737-500, we encountered light to moderate choppy conditions. We asked the center controller if the lower altitudes were reported smoother. The response was affirmative and that FL290 was reported to be smoother. We then requested FL290 and the controller replied, 'roger, I will show FL290 as your final.' we began a shallow descent to FL290 when the captain confirmed our new altitude and the controller responded that we were never 'cleared' to FL290. We immediately began a climb back to FL330. The aircraft only lost 500 ft when we began the climb back to FL330. This communication confusion could have been averted if standard pilot/ATC communication was used. The controller should have stated, 'maintain FL330 and expect FL290 as your final.'
Original NASA ASRS Text
Title: FLC OF A B737-500 BELIEVED THAT THEY WERE CLRED TO A LOWER ENRTE ALT AND STARTED DSNDING. HOWEVER, AFTER QUERYING THE ARTCC CTLR, HE HAD NOT INTENDED THEM TO DSND UNTIL INSTRUCTED TO DO SO.
Narrative: DURING CRUISE AT FL330 IN OUR B737-500, WE ENCOUNTERED LIGHT TO MODERATE CHOPPY CONDITIONS. WE ASKED THE CTR CTLR IF THE LOWER ALTS WERE RPTED SMOOTHER. THE RESPONSE WAS AFFIRMATIVE AND THAT FL290 WAS RPTED TO BE SMOOTHER. WE THEN REQUESTED FL290 AND THE CTLR REPLIED, 'ROGER, I WILL SHOW FL290 AS YOUR FINAL.' WE BEGAN A SHALLOW DSCNT TO FL290 WHEN THE CAPT CONFIRMED OUR NEW ALT AND THE CTLR RESPONDED THAT WE WERE NEVER 'CLRED' TO FL290. WE IMMEDIATELY BEGAN A CLB BACK TO FL330. THE ACFT ONLY LOST 500 FT WHEN WE BEGAN THE CLB BACK TO FL330. THIS COM CONFUSION COULD HAVE BEEN AVERTED IF STANDARD PLT/ATC COM WAS USED. THE CTLR SHOULD HAVE STATED, 'MAINTAIN FL330 AND EXPECT FL290 AS YOUR FINAL.'
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.