Narrative:

Somewhere between FL250 and FL180 the right pack light came on. First officer was pilot flying (PF). He grabbed QRH because captain was making HF radio call. QRH said: choose warmer temperature on auto-temp switches; then push 'trip reset' button [overhead the F.O.]. First officer did this whilst captain was distracted; then continued with pack checklist. Because the pack light was still illuminated; first officer turned rt pack switch off and closed the isolation valve. Continued items of pack checklist on QRH without input from monitoring pilot. At some point below FL150 press controller switched to manual; valve moved towards open. The cabin warning horn+light on when acft passing FL145. Horn/light went out 25secs later; acft passing 10;000ft. Capt called flt attds quickly briefed them to prepare cabin to land. PA to passengers to remain seated; cabin air safe to breathe. Called airport advisory freq with position and flight path and runway winds request. Completed approach + landing checklist. Normal landing. Normal taxi in/parking.

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Original NASA ASRS Text

Title: B737 flight crew reported the aircraft became depressurized following confusion while running the QRH procedure after receiving air condition and pack lights near top of descent.

Narrative: Somewhere between FL250 and FL180 the Right Pack light came on. First Officer was Pilot Flying (PF). He grabbed QRH because Captain was making HF radio call. QRH said: choose warmer TEMP on auto-temp switches; then push 'Trip reset' button [overhead the F.O.]. FO did this whilst Captain was distracted; then continued with Pack checklist. Because the PACK light was still illuminated; First Officer turned RT Pack switch OFF and closed the isolation valve. Continued items of Pack checklist on QRH without input from Monitoring pilot. At some point below FL150 Press controller switched to Manual; valve moved towards OPEN. The Cabin warning horn+light ON when acft passing FL145. Horn/light went out 25secs later; acft passing 10;000ft. Capt called Flt Attds quickly briefed them to prepare cabin to land. PA to Passengers to remain seated; cabin air safe to breathe. Called Airport Advisory freq with position and flight path and Runway winds request. Completed Approach + landing checklist. Normal landing. Normal taxi in/parking.

Data retrieved from NASA's ASRS site 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.