Narrative:

Approximately 1 hour and 15 minutes into the flight (at cruise altitude of FL380 for 40 minutes) flight attendant notified cockpit crew that there was an odor similar to burning rubber noticed in the cabin in the vicinity of the exit rows in main cabin. #1 flight attendant (flight attendant) said odor was only noticed by cabin crew; no passengers had complained. The odor was not overwhelming; was isolated to the seat rows around the emergency exits and was not getting any stronger. After 10 minutes I inquired as to status of odor. #1 flight attendant said intensity was the same; however the area affected had moved aft a few more rows. I told the #1 flight attendant to shut off power to power ports and to let me know if there is any change in the odor. Checked back with #1 flight attendant approximately 10 minutes later. She said there was no change in strength of odor; but that she did notice that it was stronger closer to the cabin floor. I elected to start executing the smoke; fire or fumes checklist in the QRH to try to isolate the cause of the fumes and resolve the issue. After approximately five minutes #1 flight attendant said odor seemed to be getting stronger. Based on this information I opted to divert to get the aircraft on the ground before the condition worsened. We were 85 miles south of zzzzz waypoint. Coordinated with [ATC] to divert. ATC cleared us direct to [a diversion airport]. [When we landed; we] had air and rescue fire fighter (arff) standing by for landing and had them follow aircraft to the gate. Due to minimal traffic in [the] area; no traffic priority was given by ATC.

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Original NASA ASRS Text

Title: The Captain of a B737-800 reported of a diversion due to a burning odor in the cabin.

Narrative: Approximately 1 hour and 15 minutes into the flight (at cruise altitude of FL380 for 40 minutes) flight attendant notified cockpit crew that there was an odor similar to burning rubber noticed in the cabin in the vicinity of the exit rows in main cabin. #1 Flight Attendant (FA) said odor was only noticed by cabin crew; no passengers had complained. The odor was not overwhelming; was isolated to the seat rows around the emergency exits and was not getting any stronger. After 10 minutes I inquired as to status of odor. #1 FA said intensity was the same; however the area affected had moved aft a few more rows. I told the #1 FA to shut off power to power ports and to let me know if there is any change in the odor. Checked back with #1 FA approximately 10 minutes later. She said there was no change in strength of odor; but that she did notice that it was stronger closer to the cabin floor. I elected to start executing the Smoke; Fire or Fumes checklist in the QRH to try to isolate the cause of the fumes and resolve the issue. After approximately five minutes #1 FA said odor seemed to be getting stronger. Based on this information I opted to divert to get the aircraft on the ground before the condition worsened. We were 85 miles south of ZZZZZ waypoint. Coordinated with [ATC] to divert. ATC cleared us direct to [a diversion airport]. [When we landed; we] had Air and Rescue Fire Fighter (ARFF) standing by for landing and had them follow aircraft to the gate. Due to minimal traffic in [the] area; no traffic priority was given by ATC.

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.