Aircraft Equipment Problem Critical; Inflight Event / Encounter Weather / Turbulence
Aircraft Equipment Problem Dissipated; Flight Crew Took Evasive Action
Aircraft
While cruising at 27000 feet in icing conditions; both packs failed shortly after tail deicing was selected.  A descent to a lower altitude was initiated.  The packs resumed normal operations at about 16000 feet.  We had at this time exited icing conditions.  All deicing systems were engaged prior to the event and had been operating for about 20 - 25 minutes when failures occurred.  Engines were operating at normal power for flight at 27000 feet and 280 knots.  Cabin reached an altitude of 7000 - 7500; before pressurization was restored.  No abnormal deicing annunciators lights were observed until after pack failure.  I believe the pressurization flow annunciator was the only abnormal light on; as it should have been on.  Remainder of the flight was normal with packs on and anti-icing turned off.
MD-82 pilot experiences a dual pack failure at FL270 shortly after tail deicing was selected. A descent to a lower altitude is initiated and the packs return to normal operation passing 16;000 feet.