Altitude deviation while flying into area of turbulence.

Attributes
ACN	296008
Time
Date	199502
Day	Fri
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : atl
State Reference	GA
Altitude	msl bound lower : 9700 msl bound upper : 10000
Environment
Flight Conditions	IMC
Light	Night
Aircraft 1
Controlling Facilities	tracon : atl
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	climbout : intermediate altitude
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 130 flight time total : 9750 flight time type : 1100
ASRS Report	296008
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument pilot : atp pilot : flight engineer
Experience	flight time last 90 days : 75 flight time total : 4000 flight time type : 1225
ASRS Report	296132
Events
Anomaly	altitude deviation : excursion from assigned altitude inflight encounter : weather
Independent Detector	aircraft equipment other aircraft equipment : unspecified 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	other

Narrative:

At takeoff there were rain showers to the south that caused delays on the departure rtes. After takeoff on runway 9L we were given a vector to 155 degrees by atlanta departure control. At 4000 ft MSL departure asked us to expedite through 6000 ft MSL for traffic. The controller was very busy because of the rainshowers in the area and frequency congestion. We heard the aircraft that took off prior to us (air carrier) say the ride wasn't bad. We asked departure controller about the ride because of the rainshowers ahead and he said other aircraft sent on the 155 degree heading had no problems. We encountered heavy rain at 10000 ft MSL and experienced light to moderate chop and multiple static discharges. We asked for higher and department said as soon as we could take a 220 degree heading we could start climbing. I had the radar tilt set at plus 5 degrees in anticipation of a continued climb and there were no returns towards the southwest. I started a turn and once established on a 220 degree heading we tried to get a climb clearance but departure was very busy, and we remained at 10000 ft MSL. As we completed the turn to 220 degrees, heavy rain appeared on the radar screen. We encountered moderate turbulence and a downdraft that forced the aircraft to descend. The autoplt could not hold the assigned altitude and I disconnected it and manually flew the aircraft back to 10000 ft MSL. This was a very inopportune time to be hand flying and aircraft. The altitude deviation was approximately 300 ft low. The information from departure about the ride and WX was inaccurate probably because we were held down to 10000 ft MSL for so long. Supplemental information from acn 296132: I think until now we were looking over the rain (tilt too high, set for climb). No climb clearance and turbulence began again with heavy rain. A sudden downdraft started the aircraft to sink. The autoplt did not correct the altitude and the captain disconnected the autoplt and climbed back to 10000 ft.

Original NASA ASRS Text

Title: ALTDEV WHILE FLYING INTO AREA OF TURB.

Narrative: AT TKOF THERE WERE RAIN SHOWERS TO THE S THAT CAUSED DELAYS ON THE DEP RTES. AFTER TKOF ON RWY 9L WE WERE GIVEN A VECTOR TO 155 DEGS BY ATLANTA DEP CTL. AT 4000 FT MSL DEP ASKED US TO EXPEDITE THROUGH 6000 FT MSL FOR TFC. THE CTLR WAS VERY BUSY BECAUSE OF THE RAINSHOWERS IN THE AREA AND FREQ CONGESTION. WE HEARD THE ACFT THAT TOOK OFF PRIOR TO US (ACR) SAY THE RIDE WASN'T BAD. WE ASKED DEP CTLR ABOUT THE RIDE BECAUSE OF THE RAINSHOWERS AHEAD AND HE SAID OTHER ACFT SENT ON THE 155 DEG HDG HAD NO PROBS. WE ENCOUNTERED HEAVY RAIN AT 10000 FT MSL AND EXPERIENCED LIGHT TO MODERATE CHOP AND MULTIPLE STATIC DISCHARGES. WE ASKED FOR HIGHER AND DEPT SAID AS SOON AS WE COULD TAKE A 220 DEG HDG WE COULD START CLBING. I HAD THE RADAR TILT SET AT PLUS 5 DEGS IN ANTICIPATION OF A CONTINUED CLB AND THERE WERE NO RETURNS TOWARDS THE SW. I STARTED A TURN AND ONCE ESTABLISHED ON A 220 DEG HDG WE TRIED TO GET A CLB CLRNC BUT DEP WAS VERY BUSY, AND WE REMAINED AT 10000 FT MSL. AS WE COMPLETED THE TURN TO 220 DEGS, HEAVY RAIN APPEARED ON THE RADAR SCREEN. WE ENCOUNTERED MODERATE TURB AND A DOWNDRAFT THAT FORCED THE ACFT TO DSND. THE AUTOPLT COULD NOT HOLD THE ASSIGNED ALT AND I DISCONNECTED IT AND MANUALLY FLEW THE ACFT BACK TO 10000 FT MSL. THIS WAS A VERY INOPPORTUNE TIME TO BE HAND FLYING AND ACFT. THE ALTDEV WAS APPROX 300 FT LOW. THE INFO FROM DEP ABOUT THE RIDE AND WX WAS INACCURATE PROBABLY BECAUSE WE WERE HELD DOWN TO 10000 FT MSL FOR SO LONG. SUPPLEMENTAL INFO FROM ACN 296132: I THINK UNTIL NOW WE WERE LOOKING OVER THE RAIN (TILT TOO HIGH, SET FOR CLB). NO CLB CLRNC AND TURB BEGAN AGAIN WITH HEAVY RAIN. A SUDDEN DOWNDRAFT STARTED THE ACFT TO SINK. THE AUTOPLT DID NOT CORRECT THE ALT AND THE CAPT DISCONNECTED THE AUTOPLT AND CLBED BACK TO 10000 FT.

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.