Narrative:

We were on a scheduled flight when on final approach; the landing gear indicators did not show green after gear extension. I was the pilot flying; the captain extended the gear lever and we heard what sounded like normal gear noise. The panel indicators showed 1 red light for the nose gear; no lights on either main gear. We executed a go-around from 2;000 ft MSL and were handed off to approach control; who asked us to climb to 3;000 ft. I remained pilot flying while the captain accomplished the 'gear lights disagreement' checklist in the quick reference handbook. As I was flying; I did not follow along with my QRH. Upon completion; the green lights were still not illuminated; so the captain performed the manual gear extension checklist. He went into the cabin to view the gear down stripes through the viewing port and returned stating that due to distortion in the port; it was unclear if the gear were actually down and locked. We extended the flaps to 25 degrees and retarded the throttles to see if the gear horn would sound; and it did. We felt that the gear were most likely down; but not certain of it. At this point; we declared an emergency; asked to have crash fire rescue standing by; and briefed the lead flight attendant. I turned over pilot flying duties to the captain; and then reviewed the 'partial or gear up landing' checklist. I noted that a circuit breaker could be pulled to silence the gear horn. The checklist wasn't specific about its location (just 'the P6 panel'); so I began searching for this circuit breaker. At this time I discovered the 'air/ground relay and lights' circuit breaker was popped. After conferring with the captain; we reset this breaker. Now all gear lights indicated green. I resumed pilot flying duties and made a normal landing. I later noted that checking the status of this breaker is the first item on the 'gear lights disagreement' checklist. I don't know if the captain missed this checklist item; if the circuit breaker wasn't popped at the time; or if he was just not able to see it popped in the dim lighting. In any case; if we had discovered this earlier; we could have saved a great deal of time; effort and apprehension on the part of the passengers. I might have trapped this error had I followed along with the QRH checklist; but that is not how we are currently trained. My job was to concentrate on flying the aircraft unless a checklist item specifically calls for me to confirm a step. I would recommend that the gear viewing ports be periodically inspected to see that they are clear and undistorted; especially under night conditions with wheel well lighting only.

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Original NASA ASRS Text

Title: A B737-400's main landing gear green lights failed to illuminate with the gear handle down. While performing the 'Gear Lights Disagree' checklist the 'AIR/GND RELAY & LTS' circuit breaker's extension was missed. A normal landing followed resetting the CIRCUIT BREAKER.

Narrative: We were on a scheduled flight when on final approach; the landing gear indicators did not show green after gear extension. I was the pilot flying; the Captain extended the gear lever and we heard what sounded like normal gear noise. The panel indicators showed 1 red light for the nose gear; no lights on either main gear. We executed a go-around from 2;000 FT MSL and were handed off to approach control; who asked us to climb to 3;000 FT. I remained pilot flying while the Captain accomplished the 'Gear Lights Disagreement' checklist in the Quick Reference Handbook. As I was flying; I did not follow along with my QRH. Upon completion; the green lights were still not illuminated; so the Captain performed the manual gear extension checklist. He went into the cabin to view the gear down stripes through the viewing port and returned stating that due to distortion in the port; it was unclear if the gear were actually down and locked. We extended the flaps to 25 degrees and retarded the throttles to see if the gear horn would sound; and it did. We felt that the gear were most likely down; but not certain of it. At this point; we declared an emergency; asked to have Crash Fire Rescue standing by; and briefed the lead Flight Attendant. I turned over pilot flying duties to the Captain; and then reviewed the 'Partial or Gear Up Landing' checklist. I noted that a CB could be pulled to silence the gear horn. The checklist wasn't specific about its location (just 'the P6 panel'); so I began searching for this CB. At this time I discovered the 'Air/Ground Relay and Lights' CB was popped. After conferring with the Captain; we reset this breaker. Now all gear lights indicated green. I resumed pilot flying duties and made a normal landing. I later noted that checking the status of this breaker is the first item on the 'Gear Lights Disagreement' checklist. I don't know if the Captain missed this checklist item; if the CB wasn't popped at the time; or if he was just not able to see it popped in the dim lighting. In any case; if we had discovered this earlier; we could have saved a great deal of time; effort and apprehension on the part of the passengers. I might have trapped this error had I followed along with the QRH checklist; but that is not how we are currently trained. My job was to concentrate on flying the aircraft unless a checklist item specifically calls for me to confirm a step. I would recommend that the gear viewing ports be periodically inspected to see that they are clear and undistorted; especially under night conditions with wheel well lighting only.

Data retrieved from NASA's ASRS site as of April 2012 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.