Narrative:

Approximately xa:20 into the flight at cruise FL370 the green left main gear down and locked indicator light on the forward panel illuminated. There were no other indications of any malfunction. There is no associated QRH procedure. We contacted [maintenance control] and they looked and agreed that it was a faulty indication. We asked dispatch for burn data with the gear down to ZZZ; ZZZ1 and ZZZ2 just in case the gear did come down in flight. They had trouble giving us that data. He was able to get us burn numbers with gear pinned down for ferry information but it took probably 20 minutes or more and was only able to provide that we would go back to ZZZ1.because we had an irregular gear indication we decided the safest course of action was to declare an emergency and have the arff equipment standing by on landing. We briefed the flight attendants that we anticipated a normal landing but we would be informing the passengers there was an abnormal indication and that the fire trucks would be inspecting us on landing. The flight attendants were told not to prepare for evacuation unless we got an unsafe indication on the approach and we would go around and brief them of such. We made a PA about the fire trucks at top of decent. We continued in; put the gear down very early; got normal indications and continued to a normal landing. We cleared the runway and stopped and the arff guys noted nothing abnormal. Out of an abundance of caution we had maintenance come out and pin the gear and tow us to the gate. In the decent the captain noted that while all 3 airspeed indicators were showing 335kts that his barber pole was dropping down to 320 kts while mine was at 340. His showed us 15 kts overspeed into the barber pole. There were no other indications of any malfunction but I slowed down to 270kts. During the rollout we did get a pseu light on the overhead and a master caution. That light remained on until parked at the gate. The barber pole on the captain side was matching mine again by somewhere above 10;000 [feet].

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Original NASA ASRS Text

Title: Pilot reported that in cruise; left main gear green down and locked light illuminated; causing the flight crew to advise ATC and make a precautionary emergency landing.

Narrative: Approximately XA:20 into the flight at cruise FL370 the Green Left Main Gear down and locked indicator light on the forward panel illuminated. There were no other indications of any malfunction. There is no associated QRH procedure. We contacted [Maintenance Control] and they looked and agreed that it was a faulty indication. We asked dispatch for burn data with the gear down to ZZZ; ZZZ1 and ZZZ2 just in case the gear did come down in flight. They had trouble giving us that data. He was able to get us burn numbers with gear pinned down for ferry information but it took probably 20 minutes or more and was only able to provide that we would go back to ZZZ1.Because we had an irregular gear indication we decided the safest course of action was to declare an emergency and have the ARFF equipment standing by on landing. We briefed the flight attendants that we anticipated a normal landing but we would be informing the passengers there was an abnormal indication and that the fire trucks would be inspecting us on landing. The flight attendants were told not to prepare for evacuation unless we got an unsafe indication on the approach and we would go around and brief them of such. We made a PA about the fire trucks at top of decent. We continued in; put the gear down very early; got normal indications and continued to a normal landing. We cleared the runway and stopped and the ARFF guys noted nothing abnormal. Out of an abundance of caution we had maintenance come out and pin the gear and tow us to the gate. In the decent the captain noted that while all 3 airspeed indicators were showing 335kts that his barber pole was dropping down to 320 kts while mine was at 340. His showed us 15 kts overspeed into the barber pole. There were no other indications of any malfunction but I slowed down to 270kts. During the rollout we did get a PSEU light on the overhead and a master caution. That light remained on until parked at the gate. The barber pole on the captain side was matching mine again by somewhere above 10;000 [feet].

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.