Narrative:

We started both engines and turned off the APU. Upon taxi; I noticed an acrid/dirty socks/musty smell when I added power. As I backed off the power on taxi; the smell seemed to dissipate. On power up taking the runway (xxl); the smell returned. I made the decision to continue the takeoff and said to the first officer that if this doesn't dissipate and go away we should return and he agreed. Once airborne; it got even worse and became a significant fume event. We donned O2 masks and goggles; I [advised ATC] due to fumes in the cockpit and we returned to land on [runway] xxl. The first officer flew and landed. I talked to ATC and ran the fumes/odor/smoke checklist. We landed uneventfully 2;000 lbs overweight. Holding short of the runway; I called back to the purser and asked him if he smelled anything. He said he didn't but would check in the back. I told him what we had experienced and that we would be returning if it continued. According to the flight attendants after landing; the smell was significant in the back of the plane and they said their eyes were burning as well. Upon arriving back at the gate; we were met by arff personnel and [company] maintenance. Firefighters boarded the plane and noticed the fumes as well; which were still present. The mechanic said they had done a 'compressor wash' the previous night and that it was his opinion that oil may have been freed from the compressors and entered the cabin. I was handed a smoke/fumes/odor form to fill out; which I did and returned it to station operations. Although some of the flight attendants complained to me about headaches and eyes burning; they declined to be checked out and told inflight operations they were fine and good to continue. I called the [duty manager] and we completed the human factors checklist. My chief pilot called to check on us and we said that while we may change our fit-for-duty status; for now; we were ok to continue. After talking about this more with the first officer; we decided we were no longer fit for duty and advised the [duty manager].

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Original NASA ASRS Text

Title: B-737 flight crew reported a significant fume event shortly after takeoff resulting in an uneventful air return.

Narrative: We started both engines and turned off the APU. Upon taxi; I noticed an acrid/dirty socks/musty smell when I added power. As I backed off the power on taxi; the smell seemed to dissipate. On power up taking the Runway (XXL); the smell returned. I made the decision to continue the takeoff and said to the First Officer that if this doesn't dissipate and go away we should return and he agreed. Once airborne; it got even worse and became a significant fume event. We donned O2 masks and goggles; I [advised ATC] due to fumes in the cockpit and we returned to land on [Runway] XXL. The First Officer flew and landed. I talked to ATC and ran the Fumes/Odor/Smoke Checklist. We landed uneventfully 2;000 lbs overweight. Holding short of the runway; I called back to the Purser and asked him if he smelled anything. He said he didn't but would check in the back. I told him what we had experienced and that we would be returning if it continued. According to the flight attendants after landing; the smell was significant in the back of the plane and they said their eyes were burning as well. Upon arriving back at the gate; we were met by ARFF personnel and [Company] Maintenance. Firefighters boarded the plane and noticed the fumes as well; which were still present. The mechanic said they had done a 'compressor wash' the previous night and that it was his opinion that oil may have been freed from the compressors and entered the cabin. I was handed a Smoke/Fumes/Odor Form to fill out; which I did and returned it to Station Operations. Although some of the flight attendants complained to me about headaches and eyes burning; they declined to be checked out and told Inflight Operations they were fine and good to continue. I called the [Duty Manager] and we completed the human factors checklist. My Chief Pilot called to check on us and we said that while we may change our fit-for-duty status; for now; we were OK to continue. After talking about this more with the First Officer; we decided we were no longer fit for duty and advised the [Duty Manager].

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.