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A widebody transport crew made an emergency descent to escape clear air turbulence, then had to make a turn to avoid another aircraft.
| Attributes | |
| ACN | 239998 |
| Time | |
| Date | 199304 |
| Day | Mon |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | atc facility : mmd airport : fra |
| State Reference | FO |
| Altitude | msl bound lower : 22500 msl bound upper : 31000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : cfff |
| Operator | common carrier : air carrier |
| Make Model Name | Widebody, Low Wing, 2 Turbojet Eng |
| Navigation In Use | Other Other |
| Flight Phase | climbout : intermediate altitude descent other other |
| Flight Plan | IFR |
| Aircraft 2 | |
| Make Model Name | Any Unknown or Unlisted Aircraft Manufacturer |
| Flight Phase | cruise other |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp pilot : commercial pilot : instrument |
| Experience | flight time last 90 days : 200 flight time total : 14000 flight time type : 3500 |
| ASRS Report | 239998 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : flight engineer pilot : atp |
| Experience | flight time last 90 days : 175 flight time total : 10000 flight time type : 280 |
| ASRS Report | 240816 |
| Events | |
| Anomaly | altitude deviation : excursion from assigned altitude conflict : airborne less severe inflight encounter : weather non adherence : clearance other anomaly other other spatial deviation |
| Independent Detector | aircraft equipment other aircraft equipment : unspecified other flight crewa |
| Resolutory Action | controller : issued new clearance flight crew : took evasive action flight crew : exited adverse environment flight crew : declared emergency |
| Consequence | other |
| Miss Distance | horizontal : 9000 vertical : 500 |
| Supplementary | |
| Primary Problem | Weather |
Narrative:
Encountered very severe turbulence, so violent that unable to maintain cruise altitude of FL310. Made descent to FL225 before able to recover at FL230. (Had notified maastricht control leaving about FL280 of descent.) they pointed out traffic at FL220 and we had visual as well as TCASII on traffic. Made slight right turn to miss traffic and no problem to either aircraft. Returned to fra, was uneventful and severe turbulence and over weight inspection done on aircraft at fra. No passenger injuries. Flight crew bruises, slight cuts and neck strain. Supplemental information from acn 240816: at FL310 we encountered severe CAT, in rhythmic waves at a frequency of approximately 2 waves per second. Amplitude was such that it was impossible to read the aircraft instruments. Once I realized that it was not a short lived incident, I initiated an emergency descent. The captain declared an emergency with maastricht control. The only system that was affected was the IRS. All 3 were on direct current power. We refueled and resumed our trip.
Original NASA ASRS Text
Title: A WDB CREW MADE AN EMER DSCNT TO ESCAPE CLR AIR TURB, THEN HAD TO MAKE A TURN TO AVOID ANOTHER ACFT.
Narrative: ENCOUNTERED VERY SEVERE TURB, SO VIOLENT THAT UNABLE TO MAINTAIN CRUISE ALT OF FL310. MADE DSCNT TO FL225 BEFORE ABLE TO RECOVER AT FL230. (HAD NOTIFIED MAASTRICHT CTL LEAVING ABOUT FL280 OF DSCNT.) THEY POINTED OUT TFC AT FL220 AND WE HAD VISUAL AS WELL AS TCASII ON TFC. MADE SLIGHT R TURN TO MISS TFC AND NO PROB TO EITHER ACFT. RETURNED TO FRA, WAS UNEVENTFUL AND SEVERE TURB AND OVER WT INSPECTION DONE ON ACFT AT FRA. NO PAX INJURIES. FLC BRUISES, SLIGHT CUTS AND NECK STRAIN. SUPPLEMENTAL INFO FROM ACN 240816: AT FL310 WE ENCOUNTERED SEVERE CAT, IN RHYTHMIC WAVES AT A FREQ OF APPROX 2 WAVES PER SECOND. AMPLITUDE WAS SUCH THAT IT WAS IMPOSSIBLE TO READ THE ACFT INSTS. ONCE I REALIZED THAT IT WAS NOT A SHORT LIVED INCIDENT, I INITIATED AN EMER DSCNT. THE CAPT DECLARED AN EMER WITH MAASTRICHT CTL. THE ONLY SYS THAT WAS AFFECTED WAS THE IRS. ALL 3 WERE ON DIRECT CURRENT PWR. WE REFUELED AND RESUMED OUR TRIP.
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.