An SBR1 had difficulty maintaining their altitude and speed while cruising at FL360 after they encou...

Attributes
ACN	841092
Time
Date	200906
Local Time Of Day	0601-1200
Place
Locale Reference	ZID.ARTCC
State Reference	IN
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Make Model Name	Rockwell North American Civil Twin Jet
Operating Under FAR Part	Part 91
Flight Phase	Cruise
Route In Use	Direct
Flight Plan	IFR
Person 1
Function	First Officer
Qualification	Flight Crew Air Transport Pilot (ATP) Flight Crew Multiengine Flight Crew Instrument Flight Crew Flight Instructor
Experience	Flight Crew Last 90 Days 45 Flight Crew Total 4500 Flight Crew Type 200
Events
Anomaly	Inflight Event / Encounter Weather / Turbulence

Narrative:

We were in cruise flight and thought we were traveling over the very top of severe weather. The ground based doppler showed we were entering a band of narrow storms however the onboard radar showed the storms below our path. The aircraft began to vibrate (pre-stall) and we noticed the angle of attack indicator showing we were about to stall. We asked the controller for lower and he cleared us to 36000. There was visible lightning and light hail in our IMC conditions. The aircraft descended under our control and was stabilized at 36000 when we entered VMC and climbed back to our normal cruise. We think that we entered an area of downdraft and the autopilot trimmed the nose up to the point of pre-stall. We never noticed the autopilot trimming action. As a result we are going to adjust the audio trim movement indication so it can be heard.

Original NASA ASRS Text

Title: An SBR1 had difficulty maintaining their altitude and speed while cruising at FL360 after they encountered a downdraft. They asked for and got clearance to a lower altitude.

Narrative: We were in cruise flight and thought we were traveling over the very top of severe weather. The ground based doppler showed we were entering a band of narrow storms however the onboard radar showed the storms below our path. The aircraft began to vibrate (pre-stall) and we noticed the angle of attack indicator showing we were about to stall. We asked the Controller for lower and he cleared us to 36000. There was visible lightning and light hail in our IMC conditions. The aircraft descended under our control and was stabilized at 36000 when we entered VMC and climbed back to our normal cruise. We think that we entered an area of downdraft and the autopilot trimmed the nose up to the point of pre-stall. We never noticed the autopilot trimming action. As a result we are going to adjust the audio trim movement indication so it can be heard.

Data retrieved from NASA's ASRS site as of April 2012 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.