A B737-300 flight crew failed to get gear safe indications before landing; performed a go around and performed appropriate QRH procedures including a flyby of the Tower for visual inspection. After an uneventful landing they were embarrassed to discover the cockpit light dimming switch was in the 'dim' position and all lights had been properly illuminated...but to a level insufficient to overcome the ambient lighting.
Synopsis
A B737-300 flight crew failed to get gear safe indications before landing; performed a go around and performed appropriate QRH procedures including a flyby of the Tower for visual inspection. After an uneventful landing they were embarrassed to discover the cockpit light dimming switch was in the 'dim' position and all lights had been properly illuminated...but to a level insufficient to overcome the ambient lighting.
Narrative
While cross feeding enroute; I noticed that a Fuel Pump Low Pressure light that should have been illuminated was not. I thought that the pump was stuck on. Then on downwind to base for landing; when I selected gear down; we got no light indication although we did get the normal noise associated with the gear going down. I contacted Dispatch and pulled out the QRH. Dispatch and Maintenance directed us to comply with the QRH. I took the controls and had the First Officer coordinate with the flight attendants to go back and check that the gear indicated down and locked.Because we were showing a landing fuel of 4.5 after our go-around; I set up for a fly-by of the Tower; and reviewed the QRH while the First Officer was checking the gear. I remember going to the Gear Disagree checklist and thinking that didn't apply because we didn't have a disagree; we had no indication at all. When First Officer verified that the gear was down and locked; I saw that there was a step in the Manual Extension checklist that said if we could verify that the gear was down and locked; land normally and stop. I missed note 1; however; which directs us to select bright on the bright/dim switch; and since the problem was a bad dim switch module; that would have solved our problem. But because I was looking at an arrival fuel of 3.9; I tried to accomplish all the important steps simultaneously; and ended up missing the step that would have fixed the problem.
Second reporter narrative
The Captain flew the low approach while I coordinated with the flight attendants to leave the cockpit for cabin gear viewer check. I had a little trouble finding the viewing port; and some difficulty being able to see the stripe on the left main landing gear. I was not sure if the mirror was not properly positioned; or if I was just having difficulty getting my head in the right position to see the stripe due to the life vest container being in the way. I was able to confirm safe down and locked indications on all three viewers/gear.I used my flashlight; but wished I had practiced locating the viewer during a preflight in the daylight with no customers watching. Perhaps including this on initial operating experience would be a good idea.While I appreciated the Tower Controller's willingness to perform a visual inspection of our landing gear; I really wish I had thought more about it. If that had been the only down and locked indication we had; would it have been safe to land? Are Tower Controllers qualified to make judgments about the condition of the landing gear on a 737? How low should you go on a low approach to let them observe the gear? We considered ourselves to be outside the QRH in this scenario; and while I don't think we did anything inherently unsafe in allowing the Tower to look at the gear for us; I don't know if there was any real value added. Safely within the confines of the QRH; a visual check of the landing gear through the viewing ports is sufficient to confirm three down and locked.
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.