From a Dash-7 video, I took this screenshot. I wonder what those two yellow balls are for. Anyone is willing to tell me? Jozef K. http://homepages.onsnet.nu/~jkusters/signature.jpghttp://forums.avsim.net/user_files/139821.jpg

I believe they are used to ensure the pilot's seat is at the right height. It makes sure that anyone flying the plane is viewing the instruments from the same eye level.BlairCYOW

Yes, it's a seating level...you want to move your seat up/down until you see all three balls in a straight line. But it's more for outside visual references...ensures your seating height (and therefore your visual picture) is consistent from one flight to the next.The only instrument that comes to mind which relies on a fixed seating height and viewing angle is a HUD.CheersBob ScottATP IMEL Gulfstream II-III-IV-V L-300Santiago de Chile

Thank you gentlemen for your explanation. Now that you mention THREE balls, I see the one in the middle too. At first I did not notice the third (black) one.Jozef K. http://homepages.onsnet.nu/~jkusters/signature.jpg

>...you want to move your seat up/down until you see all three balls in >a straight line. >>Cheers>>Bob Scott>ATP IMEL Gulfstream II-III-IV-V L-300>Santiago de ChileNot to nit-pick, but the pilot would line up the black ball with the right yellow ball and the co-pilot would line up the black ball with the left yellow ball. Minor difference between lining up all 3, but there is a difference in seat height depending on which way you do it.

Not to nit-pick your non-nit-pick, but we use this sort of indicator in the G-IV and G-V, and you do line up all three...there's actually a white line through the center of the balls on the Gulfstreams. Either way, though, you'd get a nice consistent seat position...CheersBob ScottATP IMEL Gulfstream II-III-IV-V L-300Santiago de Chile

During my CRJ-200 sim training we were told to use the opposite ball. I guess its different SOPs for different companies. But yes, you're right, as long as you do it the same way every time, you'll always be sitting in the same exact position, which makes a huge difference especially during the roundout and flare of the landing. If you're lucky enough to take lessons in a Cessna or Piper with height adjustable seats, make sure you set them the same way each time. You'll notice a drastic improvement over time if you do so. It's easy for me, being 6'2", to get it the same each time...drop it all the way down and crank it up just the slightest.

Not to nit-pick all the nit-picking, but it has nothing to do with SOP, but rather the design of the device. It sounds like the CRJ's version is similar to the Dash 7's pictured here in that the two side balls are canted forwards, so that each pilot would have to align the aft middle ball with the opposite side ball. On an ERJ, the design is opposite in that the two side balls are canted aft, away from the windshield frame, so that each pilot lines up the closer ball with the center ball for proper seat height. On a Gulfsteam, it sounds as though the geometry of the device is nothing like what is pictured and discussed here since wk6d says you line up three balls, which would be impossible on the CRJ's, Dash 7's and ERJ's devices.