Both md-82 packs shutdown at FL330 with engine and airfoil anti-ice on so a descent was begun immedi...

Attributes
ACN	1030864
Time
Date	201208
Local Time Of Day	1801-2400
Place
Locale Reference	ZZZ.ARTCC
State Reference	US
Environment
Flight Conditions	IMC
Light	Night
Aircraft 1
Make Model Name	MD-82
Operating Under FAR Part	Part 121
Flight Phase	Cruise
Flight Plan	IFR
Component
Aircraft Component	Air Conditioning and Pressurization Pack
Person 1
Function	Pilot Not Flying Captain
Qualification	Flight Crew Air Transport Pilot (ATP)
Person 2
Function	Pilot Flying First Officer
Events
Anomaly	Aircraft Equipment Problem Critical Inflight Event / Encounter Weather / Turbulence

Narrative:

While flying level cruise at FL330 with engine and airfoil ice protection on and established for 20 minutes; low flow light on annunciation came on indicating a climbing cabin pressure. Both pack flow indications indicated zero with a cabin pressure rising at 700 FPM. Immediately started descent to lower altitude while running appropriate checklist. With anti-ice all turned off; regained both packs and had pressurization once again at FL250. As still in icing conditions in and out of the clouds; turned back on ice protection and cross feeds. Two minutes later lost pressurization a second time with both packs shutting down. Declared an emergency this time and descended as rapidly as possible to 10;000 ft MSL. Cabin never got above 9;200 ft and warning nor did passenger oxygen masks ever deploy. As normal pressurization returned at 10;000 ft; continued 240 miles to destination with sufficient fuel for normal landing at our filed destination.

Original NASA ASRS Text

Title: Both MD-82 Packs shutdown at FL330 with engine and airfoil anti-ice ON so a descent was begun immediately. The packs recovered temporarily at FL250. After a second dual pack shutdown; an emergency was declared and the flight continued at 10;000 FT.

Narrative: While flying level cruise at FL330 with engine and airfoil ice protection on and established for 20 minutes; low flow light on annunciation came on indicating a climbing cabin pressure. Both pack flow indications indicated zero with a cabin pressure rising at 700 FPM. Immediately started descent to lower altitude while running appropriate checklist. With anti-ice all turned off; regained both packs and had pressurization once again at FL250. As still in icing conditions in and out of the clouds; turned back on ice protection and cross feeds. Two minutes later lost pressurization a second time with both packs shutting down. Declared an emergency this time and descended as rapidly as possible to 10;000 FT MSL. Cabin never got above 9;200 FT and warning nor did passenger oxygen masks ever deploy. As normal pressurization returned at 10;000 FT; continued 240 miles to destination with sufficient fuel for normal landing at our filed destination.

Data retrieved from NASA's ASRS site as of July 2013 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.

Both md-82 packs shutdown at FL330 with engine and airfoil anti-ice on so a descent was begun immediately. The packs recovered temporarily at FL250. After a second dual pack shutdown; an emergency was declared and the flight continued at 10;000 ft.