Air carrier Captain reported a dirty socks odor during initial approach. The flight crew initiated the QRH procedures and requested priority handling to the destination where a safe landing was accomplished.

Date: 2025-04 · Aircraft: B737-800 · Phase: approach

Anomalies: aircraft-equipment-problem-critical|flight-deck-cabin-aircraft-event-smoke-fire-fumes-odor

Synopsis

Air carrier Captain reported a dirty socks odor during initial approach. The flight crew initiated the QRH procedures and requested priority handling to the destination where a safe landing was accomplished.

Narrative

While establishing a 10 mile final for runway XX at ZZZ with the first officer as PF and the Captain as PM; the flight deck suddenly got very warm (15-20 degrees F hotter) when no changes had been made to any of the zone temperature selectors. There was also no corresponding increase on the air temperature gauge. Within about 10 seconds of the temperature increase; both myself and the first officer started to smell a dirty; musty gym sock odor followed by a burning rubber smell with a hint of electrical burning. The fumes made me momentarily light headed with some moderate throat irritation.We both donned our oxygen masks and established crew communication. I notified ZZZ tower that we had fumes in the flight deck and that both pilots were now using the oxygen masks. The tower controller asked if we wanted to [request priority handling] and I said yes given the fact that we were both on oxygen and I didn't yet know how bad the fumes were in the cabin or if they were going to get worse. We had also gotten high on the approach while we were putting on our oxygen masks so I told ZZZ tower to break us off the approach and vector us back to a downwind and base for the visual to runway XX. The FO called for the Smoke; Fire; or Fumes checklist. I ran the QRC first. At step 4 of the QRC I contacted the number 1 FA (Flight Attendant) on the inter phone. I asked if she could smell anything and she reported that she smelled a strong burning tire smell in the forward galley that seemed to be coming from under the flight deck door. I advised her that we would be landing normally but that safety vehicles with their lights on would be present after landing. I also told her to call me if there was a significant change in cabin conditions or if anyone needed medical assistance.After speaking with the number 1 FA; I continued with the QRH for Smoke; Fire; or Fumes through step 12 while the FO handled the radio and flew the aircraft on a downwind to base and final. We reported runway XX in sight and were cleared for a visual approach. At that point I discontinued the QRH to focus on PM duties for the landing. After landing; I took control at 60 knots. Tower asked if we could exit the runway and since our condition seemed to be stable; we exited the runway at taxiway 1 and told tower that we would stop there for a moment to check to see if the fumes were gone and also to check on the cabin. In hindsight I should have just stopped on the runway to allow ARFF (airport rescue and firefighting) more access to the aircraft if we needed them. Lesson learned.We removed our oxygen masks and the fumes were no longer present. I called the number 1 FA and she said everything was fine in the cabin and that the fumes had dissipated. I then made a short PA to the passengers to tell them that we had an issue just prior to landing and that they would see safety vehicles with their lights on near the aircraft but that it was just a standard precaution. We then proceeded to the gate normally but with ARFF following us.Once at the gate; we deplaned normally with the exception that cabin lighting was unavailable due to QRH checklist items but there was enough light from open window shades that it wasn't too dark. The FA's did caution the passengers to take care due to dimmer than normal lighting conditions. In hindsight; I should have turned on the emergency exit lights to assist with cabin lighting for deplaning but I didn't think of it at the time. Another lesson learned.ARFF personnel came up to the flight deck and told me he would go check the E and E bay for any indication of fire or residual fumes. He returned and reported that everything seemed fine. I then entered the mechanical discrepancy into the logbook and contacted maintenance control. I also submitted the Smoke; Odor; and fumes worksheet and verified that maintenance control had received it. There were no reports of crew or passenger illness or injury from the event.My first officer andflight attendants all did an excellent job and I was very fortunate to have them as my crew. Also; ZZZ tower and ARFF were most helpful as well as the fantastic ZZZ operations team. Days like this are most challenging and stressful but having a great team backing me up as the Captain makes it go much smoother and better. A big thanks from me to all who helped!Cause: According to maintenance control; this was the third Smoke; Odor; and Fumes event since Day 0 on Aircraft X. After the second event; this aircraft should have been pulled from service until the cause of the fumes event was determined with 100% certainty and fixed accordingly.

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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.