Narrative:

When the first officer and I board the aircraft in ZZZ; the fuel cross valve was in the open position. Neither the first officer (first officer) or myself noticed this. We departed on schedule for our leg to ZZZ1; with the cross feed still open. The fuel config enunciation illuminated several times; and we glanced at the fuel panel but again; I did not see the x feed valve position. As the first officer called for flaps 25 on approach to ZZZ1; I noticed my yoke was highly biased toward a left wing down command. I finally saw the fuel imbalance at that time; and noticed the crossfeed open. By then; we were approximately 1;000 ft. AGL and deemed it not advisable to be changing fuel switch positions at that time. The left wing indicated 2200 pounds; the right 11;600 pounds. At 500 ft. AGL; the low fuel initiation illuminated. After shut down at the gateway; we discussed how such an event could possibly have happened; and what we would do to preclude such an event in the future. Each time the fuel config light illuminated; I glanced up at the fuel panel. But I believe expectation bias took over; and I never noticed the fuel imbalance itself and the crossfeed valve open. I realize the dire consequences of not being vigilant in the situation; and I take full responsibility. In the future; when I observe a fuel config light; I will not simply 'look at the fuel panel;' but will analyze what information the system is try to tell me. I also realize I should've written this up in the maintenance log; as we clearly exceeded aom limitations.

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Original NASA ASRS Text

Title: Air Carrier flight crew reported inadvertently leaving a fuel crossfeed valve open; resulting in a fuel imbalance.

Narrative: When the First Officer and I board the aircraft in ZZZ; the fuel cross valve was in the open position. Neither the FO (First Officer) or myself noticed this. We departed on schedule for our leg to ZZZ1; with the cross feed still open. The fuel config enunciation illuminated several times; AND we glanced at the fuel panel but again; I did not see the x feed valve position. As the FO called for flaps 25 on approach to ZZZ1; I noticed my yoke was highly biased toward a left wing down command. I finally saw the fuel imbalance at that time; and noticed the crossfeed open. By then; we were approximately 1;000 ft. AGL and deemed it not advisable to be changing fuel switch positions at that time. The left wing indicated 2200 pounds; the right 11;600 pounds. At 500 ft. AGL; the LOW FUEL initiation illuminated. After shut down at the gateway; we discussed how such an event could possibly HAVE happened; and what we would do to preclude such an event in the future. Each time the fuel config light illuminated; I glanced up at the fuel panel. But I believe expectation bias took over; and I never noticed the fuel imbalance itself and the crossfeed valve open. I realize the dire consequences of not being vigilant in the situation; and I take full responsibility. In the future; when I observe a fuel config light; I will not simply 'look at the fuel panel;' but will analyze what information the system is try to tell me. I also realize I should've written this up in the maintenance log; as we clearly exceeded AOM limitations.

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.