Papi lights

Discussion in 'Pilot Training' started by Propdude, Jul 28, 2020.

  1. Propdude

    Propdude Filing Flight Plan

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    Papi lights.. do they make landings easier?
    Do you prefer them? Or does it really not matter, because you can adjust altitude without needing them?

    Had this discussion with a fellow pilot, and we couldn’t agree on an answer.
    So I figured I’d join this forum here and see what you guys think.
     
  2. AggieMike88

    AggieMike88 Touchdown! Greaser!

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    Yes, yes, does matter
     
  3. Shawn

    Shawn En-Route

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    I likey Papi

    ...lights...I like papi lights.
     
  4. Sierra_Hotel

    Sierra_Hotel Pre-takeoff checklist

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    Required? No. Nice to have? Definitely.
     
  5. Lndwarrior

    Lndwarrior Pre-takeoff checklist

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    They can be a life saver at night.

    Also help avoid trees/obstacles on approach during the day. My last and current homefield airports have trees on short approach that can grab you if you get just a little too low. Throw in an unexpected downdraft and you can be in a world of hurt.

    Can help when going into unfamiliar airports.

    Make landings easier? I don't think that's the intent.

    But they do a good job of making landings safer.
     
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  6. Kritchlow

    Kritchlow Final Approach

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    PAPI’s are generally good, but don’t solely rely on them. They are an aid, and nothing more.
    Also I have read several notams over the years where they declare the PAPI unreliable.
    If the runway has a reliable electronic GS, go with that as a primary backup to visual.
     
  7. Greg Bockelman

    Greg Bockelman Administrator Management Council Member

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    I would hope that if the PAPI was unreliable, it would be turned off.
     
  8. Jim Carpenter

    Jim Carpenter Pre-takeoff checklist

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    Though not required by FARs, IMHO, indispensable for night approach to unfamiliar, especially black-hole approach airports.
     
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  9. WannFly

    WannFly Final Approach

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    one can hope. my second solo was at a podunk field, we did a few in the pattern with the CFI onboard, first one didnt use PAPI, second one turned it on, followed it and figured it was utterly non-reliable, had to ignore the light when i did my 3 in the pattern. there was no NOTAM or anything saying the PAPI is junk
     
  10. midwestpa24

    midwestpa24 Pattern Altitude

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    For daytime flying in your average avgas burner, I don't find them terribly useful other than to point out if you are too low. In most airplanes on a 3 degree glideslope on final, you won't be able to make the field with an engine out. That means I am usually above the PAPI glideslope. However if you are seeing red, then you are obviously low. At night they make a great tool because it can be harder to determine height on final and I usually do teach to at least have one red light showing.

    As for unreliability, I guess it depends on what that means. Does that mean it may not always be on? The glideslope indication is wrong? One or more boxes OTS? That can mean a lot of things.

    A few years ago the FAA finally realized that there were numerous PAPIs on visual only runways that had never been flight checked for accuracy and obstacle clearance. The ones on instrument runways get flight checked regularly as part of the approach flight checks. They started flight checking quite a few visual PAPIs, and NOTAMs started popping up all over.
     
  11. Kritchlow

    Kritchlow Final Approach

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    Not always. I have seen it notamed as unreliable.
     
  12. Groundpounder

    Groundpounder Pattern Altitude

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  13. Matthew

    Matthew Touchdown! Greaser!

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  14. midwestpa24

    midwestpa24 Pattern Altitude

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    I'm always amazed at how some smaller airports maintain their equipment. I get it, there is no money to fix things, and often cases no permanent staff at the airport. But they would be better off shutting the PAPI down than leaving it on as "unreliable". The liability that would fall on the airport and its owner is enormous. I remember reading a story a few years ago about a jet clipping the tree tops off the end of the runway at night while the PAPI was showing proper glideslope.
     
  15. Challenged

    Challenged Pattern Altitude

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    I'm a fan.
     
  16. SkyChaser

    SkyChaser Pre-takeoff checklist

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    At the two little airports I've been to, the unreliable part of the PAPI lights just meant they didn't always come on when you keyed the mike. The tallest obstacle, though, at either airport was corn fields, so the PAPIs are not really necessary for obstacle clearance.

    When I first started practicing landings, PAPIs were awesome for making sure everything was coming together right. After several hours, I know what the sight picture and such looks like, so whether the PAPIs are on or not isn't a big deal.
     
  17. chemgeek

    chemgeek Pattern Altitude

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    • Do they make landings easier? Not really for me in daytime. At night they may be required for a legal IFR approach.
    • Do I prefer them? Neither here nor there in the daytime. Nighttime, they MAY keep you out of terrain. (But I always file IFR at night for trips.)
    So, I don't necessarily think PAPIs make for better landings, but they do help with terrain avoidance on final approach if they are working properly, especially at night.

    FYI, the PAPIs are not always aligned with the glideslope of the instrument approaches. Our airport is a case in point, although that will be changed eventually as the FAA cleans up this issue that exists at our and other airports.
     
  18. Larry in TN

    Larry in TN Pattern Altitude

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    I prefer landing on runways with no PAPI, no VASI, and no glideslope. I figure that way, nobody can tell me that I'm wrong!
     
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  19. smv

    smv Cleared for Takeoff

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    White over White - Too High
    Red over Red - Too Low
    Red over White - Just Right
    White over Red - Upside Down
     
  20. flyingron

    flyingron Touchdown! Greaser!

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    Sitting in my hangar is a military portable VASI. I bought it at the Oshkosh Aeromart about ten years ago. We keep meaning to set it up here, but by the time anybody thinks about flying in the evening, we've all been in the sauce (particularly since the airport bar opened up right where you'd place the thing).
     
  21. Jim Carpenter

    Jim Carpenter Pre-takeoff checklist

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    Even the VFR airport lights that may not get flight-checked are supposed to be periodically checked for proper angle. And, both the old-style and the newer versions of PAPIs have cut-off circuits to turn the lights off in case the angle gets out of whack, frost heaves, hit by the mower, etc. Old style was a mercury switch, new version is digital, maybe an AHRS or such. Probably still not infallible, but at least it should turn off when not aligned.
     
  22. Jaybird180

    Jaybird180 Final Approach

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    Glad I used the search function instead of starting a new thread on this specific question.

    What validation can be used to determine if one is flying such an aircraft that won't make a 3degree? Each POH provides a glide range, but suppose a pilot's trigonometry is rusty? Is there some quick math that can be used to figure this out? My trig is fine, TYVM (I think), but...

    My recent flight at a 5,000ft runway, the sight picture looked decent for me at 3 white 1 red on a 4 light PAPI. By request I descended to 2:2 and it looked too flat. I'm accustomed to airports with obstacles at both ends and having to drop in to a 22-2400ft field. Next flight, I intend to justify staying high on the GS until short final by showing the likelihood of not making the field in an engine-out.
     
    Last edited: Aug 3, 2020 at 10:33 AM
  23. smv

    smv Cleared for Takeoff

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    Who is making these requests of you?
     
  24. Jaybird180

    Jaybird180 Final Approach

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    Are you preparing for an ad hominem rebuttal? Otherwise, why would it matter. Corrected my spelling mistake above
     
  25. exncsurfer

    exncsurfer Pattern Altitude

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    From a random 172 best glide graph found on google, I plugged in the numbers, this would be no wind but your angle is more like 9 degrees vs. your PAPI 3 deg. I picked an intersection on the graph, looked like 6000 ft. and 6 nautical miles range, see angle A below:


    upload_2020-8-3_11-11-20.png
     
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  26. Jaybird180

    Jaybird180 Final Approach

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    Ha ha! yeah, the internet is cheating...
    I found that same site and the numbers from the POH says that it's 8.4degree glide for the bird I'm flying.

    With that said, I used to fly a 2-light system set for a 6 degree glide path and found it indespensible at night. I suppose it's why I'm more comfortable at the higher glide angle.
     
  27. exncsurfer

    exncsurfer Pattern Altitude

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    For me(day, VFR) the best use and probably the only time I pay attention to them is on a long straight in (issued by ATC). When you're flying a pattern it is easy to set up your descent based on your position. But on a long straight in approach, especially as a student pilot, I found it difficult to determine when to start the descent, the lights helped with that. For example approaching at pattern altitude from a distance they'll all be red, when I get 3 white one red I know its time to start descending.