Papi lights

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Propdude

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Propdude
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.
 
Yes, yes, does matter
 
Required? No. Nice to have? Definitely.
 
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.
 
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.
 
Greg Bockelman said:
I would hope that if the PAPI was unreliable, it would be turned off.
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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
 
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.
 
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Kritchlow said:
Not always. I have seen it notamed as unreliable.
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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.
 
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.
 
  • 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.
 
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!
 
White over White - Too High
Red over Red - Too Low
Red over White - Just Right
White over Red - Upside Down
 
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).
 
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.
 
midwestpa24 said:
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.
Click to expand...

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.
 
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Jaybird180 said:
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 defended to 2:2 and it looked too flat. I'm accustomed to airports with obstacles and 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.
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Who is making these requests of you?
 
Are you preparing for an ad hominem rebuttal? Otherwise, why would it matter. Corrected my spelling mistake above
 
Jaybird180 said:
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 and 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.
Click to expand...

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
 
exncsurfer said:
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:


View attachment 88505
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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.
 
Propdude said:
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.
Click to expand...
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.
 
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