 |
37000 Feet | Browse and search NASA's Aviation Safety Reporting System |
|
A flight crew encountered moderate clear air turbulence. They utilized the captain's authority/authorized to change flight levels until able to receive an amended clearance near alo.
| Attributes | |
| ACN | 456566 |
| Time | |
| Date | 199912 |
| Day | Sat |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| State Reference | IA |
| Altitude | msl bound lower : 18000 msl bound upper : 20000 |
| Environment | |
| Flight Conditions | Mixed |
| Weather Elements | Turbulence |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zau.artcc |
| Operator | common carrier : air carrier |
| Make Model Name | Large Transport, Low Wing, 2 Turbojet Eng |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | other |
| Flight Phase | cruise : level |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 180 flight time total : 18000 flight time type : 180 |
| ASRS Report | 456566 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : multi engine pilot : flight engineer pilot : atp |
| Experience | flight time last 90 days : 150 flight time total : 8000 flight time type : 1500 |
| ASRS Report | 456712 |
| Events | |
| Anomaly | altitude deviation : excursion from assigned altitude inflight encounter : turbulence non adherence : clearance |
| Independent Detector | other flight crewa other flight crewb |
| Resolutory Action | controller : issued new clearance flight crew : exited adverse environment |
| Consequence | faa : reviewed incident with flight crew |
| Supplementary | |
| Problem Areas | ATC Human Performance Weather Airspace Structure |
| Primary Problem | Weather |
| Air Traffic Incident | Pilot Deviation |
Narrative:
While cruising at FL200, we encountered heavy clear air turbulence -- moderate turbulence bordering on severe. We were talking to ZAU frequency 127.3, and my first officer attempted to contact center for clearance to a lower altitude. The controller was working several frequencys and would not respond to our calls. The turbulence was very strong and I felt we had no choice but to descend to a lower altitude. We went down to FL180 and found smoother air. Finally, ZAU answered our calls and we told them what we had done and they assigned FL180 as our altitude. I feel a contributing factor in this was controller overload, working too many sectors and frequencys. It took approximately 30 seconds to 1 min to get a response from the controller.
Original NASA ASRS Text
Title: A FLC ENCOUNTERED MODERATE CLR AIR TURB. THEY UTILIZED THE CAPT'S AUTH TO CHANGE FLT LEVELS UNTIL ABLE TO RECEIVE AN AMENDED CLRNC NEAR ALO.
Narrative: WHILE CRUISING AT FL200, WE ENCOUNTERED HVY CLR AIR TURB -- MODERATE TURB BORDERING ON SEVERE. WE WERE TALKING TO ZAU FREQ 127.3, AND MY FO ATTEMPTED TO CONTACT CTR FOR CLRNC TO A LOWER ALT. THE CTLR WAS WORKING SEVERAL FREQS AND WOULD NOT RESPOND TO OUR CALLS. THE TURB WAS VERY STRONG AND I FELT WE HAD NO CHOICE BUT TO DSND TO A LOWER ALT. WE WENT DOWN TO FL180 AND FOUND SMOOTHER AIR. FINALLY, ZAU ANSWERED OUR CALLS AND WE TOLD THEM WHAT WE HAD DONE AND THEY ASSIGNED FL180 AS OUR ALT. I FEEL A CONTRIBUTING FACTOR IN THIS WAS CTLR OVERLOAD, WORKING TOO MANY SECTORS AND FREQS. IT TOOK APPROX 30 SECONDS TO 1 MIN TO GET A RESPONSE FROM THE CTLR.
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.