BrandonBP Posted June 25, 2011 Posted June 25, 2011 Hello, I'm a noob so please bear with my noobness. Is there a difference between VASI and PAPI or is it just a matter of terminology? I've always heard the lights referred to as VASI but the PAPI lights on here look like the same system. Thanks much. I just made my 4th landing and besides stopping too long in the grass once, the other three were nice. I'm having a great time. :)
latearrival Posted June 25, 2011 Posted June 25, 2011 (edited) I'm not sure about how they are in-sim, but in real life they're both lighting systems that provide guidance for final approach. They both tell you if you're above or below the glide path. PAPI is slightly superior to VASI because there are more lights, enabling the PAPI system to also tell you if you are a little high or a little low. I *think* the VASI system is made up of two sets of lights - one white and one red. PAPI is four sets of lights - two white and two red. Could be wrong on this. Edited June 25, 2011 by latearrival corrected numbers of lights Windows 10 | i5 2500k @ 4.4Ghz | MSI GTX 970 4GB | 8GB RAM | ASRock P67 Extreme4 | Seasonic X-Series 650W PSU | Oculus Rift DK2 | CH Fighterstick, Throttle & Pedals
BlueRidgeDx Posted June 25, 2011 Posted June 25, 2011 It's best to go straight to the source: http://www.faa.gov/air_traffic/publications/atpubs/aim/Chap2/aim0201.html "They've got us surrounded again - those poor bastards!" - Lt. Col. Creighton Abrams
latearrival Posted June 25, 2011 Posted June 25, 2011 I *think* the VASI system is made up of two sets of lights - one white and one red. PAPI is four sets of lights - two white and two red. Could be wrong on this. OK, having gone to the source I wasn't quite right about this. Both systems use varying configurations of lights. However, the principle stands - VASI pretty much says 'above', 'below', 'on' glide path. PAPA says 'above', 'a little above', 'on', 'a little below', 'below'. Windows 10 | i5 2500k @ 4.4Ghz | MSI GTX 970 4GB | 8GB RAM | ASRock P67 Extreme4 | Seasonic X-Series 650W PSU | Oculus Rift DK2 | CH Fighterstick, Throttle & Pedals
effte Posted June 25, 2011 Posted June 25, 2011 (edited) Interestingly, VASI (and AVASI) installations were deleted from the ICAO documents governing the allowable visual approach aids already in 1995. If you go by the Book, i e what goes outside of the U.S., it's either T-VASI, AT-VASI, PAPI or APAPI. An AT-VASI is a normally white wing bar turning red when you are well below the approach path, three fly-up lights in front of the wing bar and three fly-down lights behind the wingbar. The fly-up/fly-down lights illuminate white one by one as you go above/below the glide slope, with the fly-up lights turning red along with the wing bar when you go well below. T-VASIs are the same, but with identical installations on either side of the runway. APAPIs are PAPIs with just two light units, showing above/below approach path. I'd hate to have to adjust the units of a T-VASI. That's a lot of sectors and units to get right, and the tolerances are rather delicate. I only ever see PAPIs in my part of the world, and the odd APAPI. I know of a couple of PLASIs as well, but I never go there so I have yet to see them. (More than you want to know, courtesy of the FAA, found here) Edited June 25, 2011 by effte ----- Introduction to UTM/MGRS - Trying to get your head around what trim is, how it works and how to use it? - DCS helos vs the real world.
BrandonBP Posted June 25, 2011 Author Posted June 25, 2011 Great explanations, diagrams, and pics. Thanks! So many acronyms and systems to learn... (I like that yellow house right under the approach lights) :D
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