Narrative:

Last leg of trip to ZZZ. At cruise flight; FL300; 50 NM east of ZZZ1 fix; the flight attendants chimed us that there was smoke in the cabin. There were 150 souls onboard the aircraft; one flight attendant in the fourth jump seat and one cockpit observer in the flight deck. I was pilot not flying. I answered the call. We immediately performed smoke in cabin memory items; put our oxygen masks on; and established communications. Captain took the radios and continued as pilot flying and I questioned the flight attendants as where they thought the smoke was coming from. They stated it was coming from the back part of the cabin. I advised the captain and we declared an emergency immediately. I had them check the rear lavatory and the aft galley; and had them feel around for any warm areas. Also; had them turn off the lights. They then said the smoke seemed to becoming from just aft of the over wing portion of the plane. Said that there was a smoke haze and could smell a strong; sweet; smoke odor. I then advised the flight attendants to continue to check where the smoke maybe coming from. We then ran the QRH. I read the QRH and had the cockpit observer follow along to double check. Closed the bus tie relay; turned off the galley power; switched the equipment cooling fans to alternate; and turned off the recirculation fan all advised via the QRH. The captain also followed along. Called the flight attendants and they said that the smoke was dissipating. We were just about 150 miles from ZZZ and; since we felt we had the problem under control and a handle on it; decided to continue on to ZZZ under emergency priority knowing that ZZZ2 would be a good alternate in case the issue would become worse. The captain continued to fly the aircraft and talk on the radios to ATC while I worked with the flight attendants and continued to run the QRH. Via the QRH; I isolated the packs and turned the right pack off. The flight attendants stated that the smoke had all dissipated at this point. The captain advised dispatch during this point. We decided since the issue was under control to leave the right pack off even if the problem was already isolated to be safe. We also continued to ZZZ under an emergency and landed with no other issues. Upon landing; advised ground that they could wave off emergency fire and rescue. Also; called operations to have maintenance waiting at the gate. Passengers deplaned with no injuries or issues.

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Original NASA ASRS Text

Title: When the B737-700 flight attendants reported smoke in the cabin the flight crew immediately donned oxygen masks; initiated the immediate action and follow up checklist items during which the smoke dissipated. They declared an emergency but; since the smoke had dissipated and the source appeared to be contained; continued to a safe landing at their destination where they canceled the emergency and turned the aircraft over to Maintenance.

Narrative: Last leg of trip to ZZZ. At cruise flight; FL300; 50 NM east of ZZZ1 fix; the flight attendants chimed us that there was smoke in the cabin. There were 150 souls onboard the aircraft; one Flight Attendant in the fourth jump seat and one Cockpit Observer in the flight deck. I was pilot not flying. I answered the call. We immediately performed Smoke in Cabin Memory Items; put our oxygen masks on; and established communications. Captain took the radios and continued as pilot flying and I questioned the flight attendants as where they thought the smoke was coming from. They stated it was coming from the back part of the cabin. I advised the Captain and we declared an emergency immediately. I had them check the rear lavatory and the aft galley; and had them feel around for any warm areas. Also; had them turn off the lights. They then said the smoke seemed to becoming from just aft of the over wing portion of the plane. Said that there was a smoke haze and could smell a strong; sweet; smoke odor. I then advised the flight attendants to continue to check where the smoke maybe coming from. We then ran the QRH. I read the QRH and had the Cockpit Observer follow along to double check. Closed the bus tie relay; turned off the galley power; switched the equipment cooling fans to alternate; and turned off the recirculation fan all advised via the QRH. The Captain also followed along. Called the flight attendants and they said that the smoke was dissipating. We were just about 150 miles from ZZZ and; since we felt we had the problem under control and a handle on it; decided to continue on to ZZZ under emergency priority knowing that ZZZ2 would be a good alternate in case the issue would become worse. The Captain continued to fly the aircraft and talk on the radios to ATC while I worked with the flight attendants and continued to run the QRH. Via the QRH; I isolated the packs and turned the right pack off. The flight attendants stated that the smoke had all dissipated at this point. The Captain advised Dispatch during this point. We decided since the issue was under control to leave the right pack off even if the problem was already isolated to be safe. We also continued to ZZZ under an emergency and landed with no other issues. Upon landing; advised Ground that they could wave off emergency fire and rescue. Also; called Operations to have Maintenance waiting at the gate. Passengers deplaned with no injuries or issues.

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.