"Because the PAPI should follow the aircraft only and not the imaginary camera"I now realize where your big misconception of how PAPI lights function lies.The PAPI does not "follow" any aircraft, imaginary camera or spot plane. PAPI lights have no clue whatsoever if there is an aircraft out there, to begin with, never mind knowing where it is.And most importantly, PAPI lights do not change.They glow the same white/red colors continuously.But they are so constructed that your eyes will only see a different color depending on their viewing angle. The viewing angle of the pilot's eyes, not of the aircraft, imaginary camera, spot plane or whatever you want to call it.So, PAPI lights "follow" nothing and nobody.It is the viewing angle of one's eyes, which defines which color they will see in the PAPI.So, in your screenshots, you are seeing these colors because the viewing angle of your eyes has moved/changed. The virtual pilot in that B747-400 is seeing different PAPI colors than you are. But the PAPI themselves are still emitting a continuous glow of red and white, and I can assure you they are not aware of either your or the B747-400's position, or even existence.Hope the above explains it for you.Stamatis

>"Also another reason why the PAPI isn't accurate. If you are flying at 35,000ft. over an airport with PAPI, the PAPI will start following that plane that is 35,000ft high.What's also interesting is when you are landing at an airport that has 2 parallel runways each with PAPI, or 2 almost parallel runways, both PAPIs will follow that same plane which is obviously on approach to only one of the runways, not two."I think you've got the wrong idea. If I understand you correctly, you think that the PAPI is aicraft specific? Not the case. If 2 aircraft are in trail of each other on final approach, both will be seeing the PAPI differently. PAPI simply emits fixed beams of light (the box doesn't move at all) . Its up to the pilot to maneuver his aircraft so that he intercepts those beams of light.[http://airportsystems.honeywell.com/images/PAPI_lge.jpg]

Hi there,>Let's say there is an Air France 747-400 about to land at night in Beirut's runway 17 and there is a spot plane next to it or behind it. Will the PAPI be following the 747 which is the aircraft about to land, or the spot plane simply flying next to it "spotting" it?You will answer that it will follow the 747, since it is the aircraft directly infront of the runway about to land, not the spot plane which will be landing later on after it makes a go-around or something.:)). Walk towards the lights from the edge of the runway. When you start walking, they're all red. The closer you get, one will turn white, then the other and so on, until you're standing right in front of them, when all will be white, as you're looking right down on them.Cheers,Gosta.http://hifi.avsim.net/activesky/images/wxrebeta.jpg

Taking all the above into context...While the PAPI's are navigational aids, the spot/external/chaseplane view is NOT a navigational aid. :) The PAPI's are configured to be useful only from the pilot's perspective, and this is illustrated by the true-to-life behaviour of the PAPI's in MSFS2002/2004. The external cameras are simply a different perspective in the flight simulator world. You should open a small cockpit window to have the pilots perspective if you want the PAPI guidance when landing in the spot plane view. -Greg

>But tell me, what is the only object you can move around in the external view? You can only move around your own plane.http://hifi.avsim.net/activesky/images/wxrebeta.jpg

Oh great...now I get it...Sorry folks, now I can see why you are saying it's accurate.Now the eyepoint thing makes sense when you are in the external view. But the reason why I still believe it's unrealistic is because the pilot is still inside the plane. You're just looking from the outside.This is one of the things that can't really be solved in a simulator I guess.Regards

>But the reason why I still believe it's unrealistic is because the pilot is still inside the plane. You're just looking from the outside.This is one of the things that can't really be solved in a simulator I guess.:).Cheers,Gosta.http://hifi.avsim.net/activesky/images/wxrebeta.jpg

>Actually, it's one of the things that works exactly as it>should :).So basically they work kind of like reflectors?Here is the real thing in real life:http://users.adelphia.net/~nabilb727/approach.JPG

>So basically they work kind of like reflectors?:). In the picture (very nice, BTW), you see that you (or whoever took it) were on the ground, therefore you see all the lights red. The pilots of the plane will have seen two white and two red.Cheers,Gosta.http://hifi.avsim.net/activesky/images/wxrebeta.jpg

Okay makes sense.Yes I took the photo. :)I was thinking PAPI works very similar to the lights on the aircraft carrier used to guide the Navy aircraft telling them they are too high or too low. Except the ones on the aircraft carriers will also tell the pilots if they are too far to the left or too far to the right.I know the ones on the aircraft carriers are lights which are controlled by crew on the carrier.How does VASI work? The same way as PAPI or is it actually lights that follow?Regards

Actually, the system used on aircraft carriers today is similar to the PAPIs. They are also a fresnel lens based system with the exception that it is gyroscopically stabilized and also does *allow* for an LSO to override and take control if necessary, such as in exceptionally rough sea states. It provides no indications for lateral displacement from centerline, only glideslope displacement is available. The pilot uses the runway markings and lights for lateral lineup cues. You don't have to take my word for it though, you can read here instead http://www.lakehurst.navy.mil/nlweb/iflols.htmlVASIs are similar to PAPIs, again a Fresnel Lens system, except that it uses boxes which are aligned vertically with respect to the pilot's viewpoint. A red upper light and white lower light indicates on glidepath. Two reds indicate too low, and two whites indicate too high.

Probably because the ILS glide slope is set up to land you deeper into the runway than the PAPI.Just a thought!Tony

I printed this thread and took it to the FBO and the CFI's about peed their pants laughing.I wonder if my MAMI is accurate?Tony

"I printed this thread and took it to the FBO and the CFI's about peed their pants laughing."One of the first things you learn as a CFI is that people learn differently. Just because you say it, doesn't mean they got it. I think it is fantastic that this gentleman took the time to learn rather than just get frustrated. If everyone were like that, our job would be a lot easier. Not everyone understands the things that some think are simple. A doctor might find my description of an common illness flawed in much the same way. He or she see's the knowledge as basic having learned about it in first year medical school. :)

>I printed this thread and took it to the FBO and the CFI's>about peed their pants laughing.>>I wonder if my MAMI is accurate?>>TonyIt really is sad how there are people like you in this world who add absolutely nothing valuable to society......I hope one day something happens in your life to make you realize what you did and correct yourself for your own sake.........