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Altitude deviation altitude excursion -- this air carrier flew over a thunderstorm and the updraft caused it to climb 700 ft above its assigned altitude.
| Attributes | |
| ACN | 306270 |
| Time | |
| Date | 199505 |
| Day | Tue |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | atc facility : mei |
| State Reference | MS |
| Altitude | msl bound lower : 31000 msl bound upper : 31700 |
| Environment | |
| Flight Conditions | IMC |
| Light | Dusk |
| Aircraft 1 | |
| Controlling Facilities | artcc : zhu |
| Operator | common carrier : air carrier |
| Make Model Name | A310 |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | Other Other |
| Flight Phase | cruise other |
| Route In Use | enroute : direct |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 60 flight time total : 5000 flight time type : 60 |
| ASRS Report | 306270 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 150 flight time total : 8500 flight time type : 500 |
| ASRS Report | 306052 |
| Events | |
| Anomaly | altitude deviation : excursion from assigned altitude inflight encounter : weather non adherence : clearance |
| Independent Detector | other controllera other flight crewa |
| Resolutory Action | flight crew : returned to intended course or assigned course |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | Pilot Deviation |
Narrative:
Following heading change direct hli VOR, the new heading took us over a cumulus buildup, at very short range. Since I had the radar scope in 120 NM range and the range of the cloud top was, in fact, inside 20 NM, I didn't identify the top of the buildup before we flew into it (the 40 degree heading change combined with the 120 NM range selected put the return off the scope or compressed at the scope nadir. The sky conditions precluded visual identify of the cumulus buildup. Upon entering the cloud top, turbulence increased significantly and a strong updraft forced the aircraft to FL317 despite the fact that the autoplt was engaged to hold FL310. Captain disconnected autoplt immediately, taking positive action aircraft to the cleared altitude of FL310. The altitude deviation lasted approximately 15 seconds in duration.
Original NASA ASRS Text
Title: ALTDEV ALT EXCURSION -- THIS ACR FLEW OVER A TSTM AND THE UPDRAFT CAUSED IT TO CLB 700 FT ABOVE ITS ASSIGNED ALT.
Narrative: FOLLOWING HDG CHANGE DIRECT HLI VOR, THE NEW HDG TOOK US OVER A CUMULUS BUILDUP, AT VERY SHORT RANGE. SINCE I HAD THE RADAR SCOPE IN 120 NM RANGE AND THE RANGE OF THE CLOUD TOP WAS, IN FACT, INSIDE 20 NM, I DIDN'T IDENT THE TOP OF THE BUILDUP BEFORE WE FLEW INTO IT (THE 40 DEG HDG CHANGE COMBINED WITH THE 120 NM RANGE SELECTED PUT THE RETURN OFF THE SCOPE OR COMPRESSED AT THE SCOPE NADIR. THE SKY CONDITIONS PRECLUDED VISUAL IDENT OF THE CUMULUS BUILDUP. UPON ENTERING THE CLOUD TOP, TURB INCREASED SIGNIFICANTLY AND A STRONG UPDRAFT FORCED THE ACFT TO FL317 DESPITE THE FACT THAT THE AUTOPLT WAS ENGAGED TO HOLD FL310. CAPT DISCONNECTED AUTOPLT IMMEDIATELY, TAKING POSITIVE ACTION ACFT TO THE CLRED ALT OF FL310. THE ALTDEV LASTED APPROX 15 SECONDS IN DURATION.
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.