Simviation Forums

ok the other day i was sitting at my local airport(KTUL) watching the planes come in and noticed the string of 4 red lights on the left side did not cahnge from red-white like they always do in the game. why did they not do this? was it because they might have been doing a visual approach instead of an ILS maybe? i dunno.

It is for the visual approach. The lights change as your viewing angle changes to tell you whether or not you're on the glideslope

as dan said, they change with the angle you view them, they dont change by how close a plane gets.

Completely normal, because you see the VASI lights from waaay below, and rightfully: they indicate just that, by showing 4 red lights  :)

Wow.  Never knew that that was how they worked.  Very informative.

what?!  ???
Don't you have airlaw and operational procedures at your school?

If you see VASI or PAPI lights in the fog when the conditions are just right, you can actually see the red and white beams of light projected from the lights light a flashlight in the dust.

what?!  ???
Don't you have airlaw and operational procedures at your school?

I know what a VASI is, I just didn't know that that was how it projected the lights...

Also, they don't just change from red to white either like they do on FS... it's a gradual transition from red to pink, to white.  

I can't imagine getting my PPL and not knowing how a VASI works.  I'm only a couple hours away, but I learned all that way before I even started flying.  It seems like it should be.... required.. maybe?!?!

It strikes me that it doesn't really matter to the pilot how it works. Just so long as it does.

It strikes me that it doesn't really matter to the pilot how it works. Just so long as it does.

That's what I was thinking  It's not anywhere in the Jeppessen reading.... should I go hide under a rock before I'm beaten to death, or should I make it easier on you guys?

im playin

Don't know why you couldn't find it in your AIM... check this link. I tried to find a good picture of a VASI or PAPI unit to no avail... basically, it's a box with lights inside that emit a split beam. Depending on the angle you're viewing it from, you'll see red or white as you approach it (then there's the red/yellow/green tricolor system). And yes, sometimes PAPIs look pink- I've seen it in RL. I think it's because although the red and white boxes are arrayed side-by-side, they're set so their light converges at a certain distance. Red plus white equals pink.
http://www.faa.gov/ATpubs/AIM/Chap2/aim0201.html

The mnemonic I was taught  for VASI:
Red over white: just right (on glideslope)
White over white: you'll fly all night (above glideslope)
Red over red: you're dead! (below glideslope)