Hopefully this question will be unusual enough to generate some responses....Looking at the Landing Gear selector in the 737 - why is there a detent for OFF?Surely it is either UP or DOWN?Probably a simple answer here, but I can't think of it...ThanksAllblack

After the landing gear is retracted and the gear doors are closed, the handle is placed in the OFF position to remove hydraulic pressure from the gear and allow the gear and doors to be held closed by their mechanical uplocks. By depressurizing the gear it prevents a leak in the landing gear/door lines from dumping all the fluid out when it is needed for the flight control systems.The DC-9 has a center uplatch check position instead of an off position but it does the same thing. It depressurizes the gear system to allow the gear to settle on the uplocks (the doors in the case of the main gear)to insure the uplocks are engaged and then the handle is placed back to the up position and when the hydraulic pumps are then placed to LOW for cruise, the hydraulic pressure is removed from the gear system and the gear settles on the doors.Probably more than you wanted to know about gear systems. :-)Ed Weber a.k.a tallpilot

Fascinating!Thanks for that. This hobby never fails to amaze.....And I thought it was going to be the dumb question for the week.CheersAllblack

Thanks to your