B757-200
Flight Crew Air Transport Pilot (ATP)
Aircraft Equipment Problem Critical
Flight Crew Landed As Precaution; Flight Crew Returned To Departure Airport; General Declared Emergency
Company Policy; Aircraft; Procedure
Right pack placarded inoperative. At approximately 4;000 FT left pack failed. Complied with QRH procedure; left pack would not reset. Informed Dispatch; declared emergency with ATC for overweight landing. Soft; uneventful landing and taxied to gate and briefed Maintenance. Do not allow Dispatch on a single pack.
[We] took off with right pack placarded inoperative. Passing approximately 4;000 FT the left packed failed. [We] followed QRH procedures to reset pack. Pack would not reset. [We] declared an emergency with ATC for an overweight landing. Notified Dispatch; landed; and taxied to gate.
B757 flight crew reports being dispatched with an inoperative pack then loosing the second pack shortly after takeoff. When pack won't reset flight returns to departure airport for an overweight landing.