An air carrier crew on approach to stl in severe turbulence beneath a thunderstorm overhang declared...

Attributes
ACN	957016
Time
Date	201107
Local Time Of Day	1201-1800
Place
Locale Reference	STL.Airport
State Reference	MO
Environment
Flight Conditions	Mixed
Light	Daylight
Aircraft 1
Make Model Name	Large Transport Low Wing 2 Turbojet Eng
Operating Under FAR Part	Part 121
Flight Phase	Initial Approach
Flight Plan	IFR
Person 1
Function	Pilot Not Flying Captain
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 224
Person 2
Function	First Officer Pilot Flying
Experience	Flight Crew Last 90 Days 187
Events
Anomaly	Deviation - Altitude Excursion From Assigned Altitude Deviation - Procedural Clearance Inflight Event / Encounter Weather / Turbulence

Narrative:

Declared emergency and descended to avoid overhang from thunderstorm. While being vectored for approach in severe turbulence; I as the pilot not flying asked approach for lower to avoid dark black overhang. The very rough air we were in at the time was only going to get worse if we were to fly into the overhang. I asked the controller for lower and he told me unable. I asked again for lower and he told me unable. I stated; 'I am declaring an emergency and descending.' I checked the TCAS and visually cleared and the pilot flying descended from 4;000 ft MSL to 3;500 ft MSL. Once we were past the overhang I told control we could climb back up. He gave us a clearance to climb to 4;000 ft; which we did. We then attempted to fly and land runway 24 at stl. Three aircraft in front broke off the approach due to weather and turbulence. As the tower called 'microburst;' we elected to go to our divert field.

Original NASA ASRS Text

Title: An Air Carrier crew on approach to STL in severe turbulence beneath a thunderstorm overhang declared an emergency in order to descend beneath it then diverted because of a microburst.

Narrative: Declared emergency and descended to avoid overhang from thunderstorm. While being vectored for approach in severe turbulence; I as the pilot not flying asked Approach for lower to avoid dark black overhang. The very rough air we were in at the time was only going to get worse if we were to fly into the overhang. I asked the Controller for lower and he told me unable. I asked again for lower and he told me unable. I stated; 'I am declaring an emergency and descending.' I checked the TCAS and visually cleared and the pilot flying descended from 4;000 FT MSL to 3;500 FT MSL. Once we were past the overhang I told Control we could climb back up. He gave us a clearance to climb to 4;000 FT; which we did. We then attempted to fly and land Runway 24 at STL. Three aircraft in front broke off the approach due to weather and turbulence. As the Tower called 'microburst;' we elected to go to our divert field.

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.

An air carrier crew on approach to stl in severe turbulence beneath a thunderstorm overhang declared an emergency in order to descend beneath it then diverted because of a microburst.