Narrative:

We takeoff on runway 15R at bwi switched over to departure control and were given a left turn to a heading of 250 degrees and climb to 9000'. Thunderstorm activity was building in the area and as we rolled out on a heading of 250 degrees we observed on our radar a line directly in front of us less than 10 NM away. We immediately requested a deviation for WX and were told by ATC that due to traffic in the area he would need us on that heading a while longer. We responded with a firm request that we required a turn now to avoid the thunderstorm activity and were given a clearance to fly any desired heading we wanted to avoid the WX. We immediately started a left turn to parallel the WX when we began to go into it. We were climbing through 7500' when the captain began reducing thrust and applying forward pressure on the yoke to level off at the assigned 9000' altitude when we encountered moderate rain and turbulence and a series of extreme updrafts. The captain reduced power to idle and pushed the nose over in an attempt to level off, but went through 9000' and finally arrested the climb at 9800' and began a descent back down when ATC advised us that our assigned altitude was 9000' and that there was 10000' traffic in the area. We hurried back down to our assigned altitude and broke out the back side of the WX. We were informed later that we had been the last departure out of bwi until the line of WX had passed. I realize that some ATC radars don't paint WX as good as some others do, but it would have been a great help to know that there was an area of deviations in reference to our route to departure. Also, when the initial deviation was requested the controller did not seem to think the request was urgent enough for action, but on the second request 20 seconds later it was and he responded with the authority/authorized turn. Supplemental information from acn 107811: just as I was attempting level off and roll out on course we hit a thunderstorm cell and encountered severe turbulence and an updraft condition. I was unable to stop the climb at 9000'. I disconnected the automatic throttle and even with a 15-20 degree nose down attitude the plane continued to climb, airspeed shot to 300 KTS.

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Original NASA ASRS Text

Title: MLG BALLOONS 800' ABOVE ASSIGNED ALT WHEN TSTM IS ENCOUNTERED.

Narrative: WE TKOF ON RWY 15R AT BWI SWITCHED OVER TO DEP CTL AND WERE GIVEN A LEFT TURN TO A HDG OF 250 DEGS AND CLB TO 9000'. TSTM ACTIVITY WAS BUILDING IN THE AREA AND AS WE ROLLED OUT ON A HDG OF 250 DEGS WE OBSERVED ON OUR RADAR A LINE DIRECTLY IN FRONT OF US LESS THAN 10 NM AWAY. WE IMMEDIATELY REQUESTED A DEVIATION FOR WX AND WERE TOLD BY ATC THAT DUE TO TFC IN THE AREA HE WOULD NEED US ON THAT HDG A WHILE LONGER. WE RESPONDED WITH A FIRM REQUEST THAT WE REQUIRED A TURN NOW TO AVOID THE TSTM ACTIVITY AND WERE GIVEN A CLRNC TO FLY ANY DESIRED HDG WE WANTED TO AVOID THE WX. WE IMMEDIATELY STARTED A LEFT TURN TO PARALLEL THE WX WHEN WE BEGAN TO GO INTO IT. WE WERE CLBING THROUGH 7500' WHEN THE CAPT BEGAN REDUCING THRUST AND APPLYING FORWARD PRESSURE ON THE YOKE TO LEVEL OFF AT THE ASSIGNED 9000' ALT WHEN WE ENCOUNTERED MODERATE RAIN AND TURB AND A SERIES OF EXTREME UPDRAFTS. THE CAPT REDUCED PWR TO IDLE AND PUSHED THE NOSE OVER IN AN ATTEMPT TO LEVEL OFF, BUT WENT THROUGH 9000' AND FINALLY ARRESTED THE CLB AT 9800' AND BEGAN A DSCNT BACK DOWN WHEN ATC ADVISED US THAT OUR ASSIGNED ALT WAS 9000' AND THAT THERE WAS 10000' TFC IN THE AREA. WE HURRIED BACK DOWN TO OUR ASSIGNED ALT AND BROKE OUT THE BACK SIDE OF THE WX. WE WERE INFORMED LATER THAT WE HAD BEEN THE LAST DEP OUT OF BWI UNTIL THE LINE OF WX HAD PASSED. I REALIZE THAT SOME ATC RADARS DON'T PAINT WX AS GOOD AS SOME OTHERS DO, BUT IT WOULD HAVE BEEN A GREAT HELP TO KNOW THAT THERE WAS AN AREA OF DEVIATIONS IN REF TO OUR ROUTE TO DEP. ALSO, WHEN THE INITIAL DEVIATION WAS REQUESTED THE CTLR DID NOT SEEM TO THINK THE REQUEST WAS URGENT ENOUGH FOR ACTION, BUT ON THE SECOND REQUEST 20 SECS LATER IT WAS AND HE RESPONDED WITH THE AUTH TURN. SUPPLEMENTAL INFO FROM ACN 107811: JUST AS I WAS ATTEMPTING LEVEL OFF AND ROLL OUT ON COURSE WE HIT A TSTM CELL AND ENCOUNTERED SEVERE TURB AND AN UPDRAFT CONDITION. I WAS UNABLE TO STOP THE CLB AT 9000'. I DISCONNECTED THE AUTO THROTTLE AND EVEN WITH A 15-20 DEG NOSE DOWN ATTITUDE THE PLANE CONTINUED TO CLB, AIRSPD SHOT TO 300 KTS.

Data retrieved from NASA's ASRS site as of August 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.