Use of PAPI's during daylight

[Parkbremse]

I was wondering how important are PAPI's (or visual landing aids in general) during daylight conditions, especially in the commercial / airliner flying world? The reason why i'm asking is that, although having passed the Holmes-Wright Coulour Vision Lantern Test as a colour weak and thus getting an unrestricted Class 1 Medical, i noticed during flight training that in certain daylight conditions, when it's hazy or a bright sunny day and with PAPI's on a low setting , i really have difficulties distinguishing the lights. However on a higher setting, or when it's getting darker i have no problems whatsoever. As i am on my way to an ATPL, this got me into some serious thinking if i am really medically fit for the job but after a good deal of thought , i could not think of a single situation where the use of PAPI's during the day is essential and where i would pose a security risk as PF. But, as my experience in flying is still very limited, i would be glad if some of the pros could answer my question.

[spekesoftly]

in certain daylight conditions, when it's hazy or a bright sunny day and with PAPI's on a low setting , i really have difficulties distinguishing the lights. However on a higher setting, or when it's getting darker i have no problems whatsoever.
By Day, 'PAPIs' should normally be set to 100% (max) brilliance anyway, and only incrementally reduced as night falls. If the brilliancy setting of any particular lighting aid is not to your liking, you could always ask ATC to adjust it accordingly, not normally a problem. (In fog conditions, there may be a minimum RWY edge light setting, required for RVR readings, but leaving that aside .... )

Also suggest you may get more replies if this was moved to the 'Questions' forum.

[Right Way Up]

Its certainly not unusual and maybe a factor of your local field PAPIs. I defy anyone to tell me what colour the PAPIs are showing at ALC on Runway 28, even at 1000 ft!:D

[Pub User]

Parkbremse

The use of PAPIs is rarely 'essential' but often very very useful. Even in the airliner world we often fly non-precision or visual approaches, and the PAPIs are an excellent aid during the latter stages of the approach, particularly if the runway has a slope, which alters its perspective slightly.

ALC runway 28 is a good example (thanks RWU), a VOR approach, and the first half of the runway slopes up quite markedly, thus giving the illusion of being too steep on the approach. When you can eventually make the PAPIs out, the damned things are all red!

[Piltdown Man]

They can be useful - but I wouldn't worry too much! For example, try an ILS in DUS, Runway 23R. Down to 200', no problem. But after that, if you let the autopilot follow the G/S down to 50' (Fokker 50) you end up with four reds. So which system is correct - well probably both. The job of the G/S in the ILS and the PAPI is to get you to a point where the Mk I eyeball and seat of the pant can do a reasonable job.

:ok:

ps The CAA don't give out "half medicals" - even the ones with restrictions are still valid.

[CarbHeatIn]

I heard an AF pilot (A340) alarmingly question the SXM tower as to whether the PAPI lights were on, on short finals in the blazing afternoon Caribean sun last June. The Tower replied affirmative.

[Old Smokey]

I have no problem with colour vision (both privately and officially), but on bright sunny days do find the Red/White colours of the PAPI difficult to differentiate above about 1000 feet, no problem below that altitude or in darker or gloomier conditions.

I would think, Parkbremse, that your colour vision is normal.

Regards,

Old Smokey

[MkVIII]

Australian T-VASI has it's benefits!

I prefer T-VASI to PAPI, but I guess it is all a matter of what you are used to.

[Khaosai]

Hi piltdown man. I think that the general consensus is to use the PAPI down to 200ft only. This would explain the erroneous indication below this alt. Rgds.

[look you]

The papis in ALC are all pink, and very fetching too.

They are by and large a comfort blanket. If you switch them off, nobody dies, but those that rely on them do heavier landings without them!

Brief yourself on the rwy slope and be ready for the predictable visual illusions. Then, make sure your aiming point doesn't move up or down the windshield once you are fully configured. Look towards the end of the runway when you flare.

And brace yourself!!!!!

[Parkbremse]

Thanks for all the responses so far, they pretty much reflect what i had already thought. :ok:

[the_flying_cop]

just to throw my tu penneth into the ring, could the PAPI's not be changed from red to white to a colour which has a greater contrast?

i love the sight of them as we come in, unless i see 3.5 reds and then have to give the captain a poke with my pencil in his thigh to see if he is still concious

not sure what alternative colours could be. my obvious choice would be red and green but i understand people with colour blindness problems have trouble distinguishing those two. (but im not sure that we are allowed colour blind pilots so that negates that problem.....

ho hum... ramble over.


TFC