I'm flying approach on LOC and gear is up. When G/S is captured, I lower flaps to 15 and a warning sound starts buzzing? It stops as soon as I start gear down. Is this simply a warning to put gear down?And more importantly, where is this explained? I've looked in both FCOMs and the FCTM and can't find anything about it.The manuals are great for reading thru but awful for finding something specific even using the PDFs and searching is problematic.

It's the gear warning horn. If it goes off before and up to flaps 10 you can push the cut-out button on the right side of the pedestal (just below the flap position indicators).Edit : Operation Manual Volume 2: 15.10.6

Edited February 13, 201214 yr by Somebody_Else

I saw in the manuals where the gear warning horn can be turned off. But what causes the warning on a normal approach? The warning gets mentioned in the manuals as occuring with excessive flaps during a go around.I can't find any mention of a warning on approach.

I think there's a minimum of 10 degrees of flaps without the landing gear down... You will also feel the airplane pull up when the gear is up at 10 degrees of flaps. Just lower them all the way down (or according to your VREF), then lower the gear.

The gear warning horn sounds with flaps extended and the throttles closed. The warning cannot be cancelled with Flaps 15 or greater, i.e. a landing flap setting. It's quite possible for the horn to sound on a normal approach if you are a little fast and the throttles close to compensate. To avoid it happening at G/S capture I usually select gear down then Flap 15.

Edited February 14, 201214 yr by kevinh

Normal configuration is:F1-F5-Gear Dn/F15-F30 or F40. You can put the gear down earlier, but don't go F15 until you've got the gear down.