The scourge of PAPI replacing T-VASIS
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The scourge of PAPI replacing T-VASIS
First of all I want to state the fact that I am not colour blind!
I was approaching Melbourne Runway 34 for the first time since the runway works had been completed and have to say that I found the new PAPI system next to useless!
We were flying in from Tasmania via HOBAY so we had the PAPI system in view for an extended period of time.
Where the old T-VASIS gave you an unambiguous indication of where you were on the visual approach path, I found the PAPI approach path information to be profoundly nebulous and quite unacceptable.
Everyone who flies in to Melbourne knows that the runway slope is quite significant on that runway. From 330 ft AMSL at the 34 threshold to 434 ft at the aerodrome reference point (which is located just 1500 metres along and 450 metres to the east of the centreline). This slope gives the illusion that you are high when on the 3 degree slope and if it wasn't for the visual slope guidance, many aircraft would approach the runway much lower than desired.
Anyway the old T-VASIS had essentially 7 separate rows of lights to indicate glide path angle (three for high and three for low). The lights were either in-view or not -in-view (which is literally as easy to interpret as black or white).
Now we have a PAPI system with just four lights in a single row which change between white and red in a progressive fashion from four red no white lights to one, two, three, and four white no red lights. The pilot is now required to perceive this difference in colour from the single light source, and also perceive a change in colour as the aircraft moves above or below the ideal glide path to the lights.
This sounds fine in theory however the reality is not quite there. Two points need to be made.
1. The white light is not white at all but rather a light shade of pink.
2. When a light is transitioning from white to red or vice versa, it does it gradually, so that the change can go unnoticed!
The other day I transitioned from 1-red 3-white, to almost 4-red 0-white without it ever really grabbing my attention. By that I mean the PAPI didn't shout out to me the changes that were happening. T-VASIS would have! It was more the fact that I realised that the picture looked normal which wasn't normal for this runway! It should have looked as though I was high. That was when I realised that the PAPI was no longer indicating 3 pink but rather 3 red lights.
Never mind the fact that the T-VASIS allows you to nominate multiple aiming points where the PAPI only allows you to nominate one. And that one point is always set up for a B747 often with an eye crossing height over the threshold of around 70 feet.
Anyway the purpose of this post is to gauge the feelings of other pilots about the apparent inevitable demise of the far-superior AUSTRALIAN T-VASIS system and wonder if there is anyway to halt and even reverse the installation of PAPI at major airports around the country.
Does anyone have information about the cost associated with installing and maintaining the two systems?
I wonder if pilots can exert any pressure on the people responsible.
I was approaching Melbourne Runway 34 for the first time since the runway works had been completed and have to say that I found the new PAPI system next to useless!
We were flying in from Tasmania via HOBAY so we had the PAPI system in view for an extended period of time.
Where the old T-VASIS gave you an unambiguous indication of where you were on the visual approach path, I found the PAPI approach path information to be profoundly nebulous and quite unacceptable.
Everyone who flies in to Melbourne knows that the runway slope is quite significant on that runway. From 330 ft AMSL at the 34 threshold to 434 ft at the aerodrome reference point (which is located just 1500 metres along and 450 metres to the east of the centreline). This slope gives the illusion that you are high when on the 3 degree slope and if it wasn't for the visual slope guidance, many aircraft would approach the runway much lower than desired.
Anyway the old T-VASIS had essentially 7 separate rows of lights to indicate glide path angle (three for high and three for low). The lights were either in-view or not -in-view (which is literally as easy to interpret as black or white).
Now we have a PAPI system with just four lights in a single row which change between white and red in a progressive fashion from four red no white lights to one, two, three, and four white no red lights. The pilot is now required to perceive this difference in colour from the single light source, and also perceive a change in colour as the aircraft moves above or below the ideal glide path to the lights.
This sounds fine in theory however the reality is not quite there. Two points need to be made.
1. The white light is not white at all but rather a light shade of pink.
2. When a light is transitioning from white to red or vice versa, it does it gradually, so that the change can go unnoticed!
The other day I transitioned from 1-red 3-white, to almost 4-red 0-white without it ever really grabbing my attention. By that I mean the PAPI didn't shout out to me the changes that were happening. T-VASIS would have! It was more the fact that I realised that the picture looked normal which wasn't normal for this runway! It should have looked as though I was high. That was when I realised that the PAPI was no longer indicating 3 pink but rather 3 red lights.
Never mind the fact that the T-VASIS allows you to nominate multiple aiming points where the PAPI only allows you to nominate one. And that one point is always set up for a B747 often with an eye crossing height over the threshold of around 70 feet.
Anyway the purpose of this post is to gauge the feelings of other pilots about the apparent inevitable demise of the far-superior AUSTRALIAN T-VASIS system and wonder if there is anyway to halt and even reverse the installation of PAPI at major airports around the country.
Does anyone have information about the cost associated with installing and maintaining the two systems?
I wonder if pilots can exert any pressure on the people responsible.
They're useless. Cheap and nasty. I believe T-VASI is about 3 times as expensive (but 3 times safer!). Affordable safety, son!
I complained to the CAA when the first one went in to MA years ago. Fell on deaf ears. If ICAO approves, we've got no chance.
I complained to the CAA when the first one went in to MA years ago. Fell on deaf ears. If ICAO approves, we've got no chance.
Many years ago and with much personal T-VASIS experience, I would have agreed with you. However, in the last 20 years my experience in international operations (including all sorts of weather conditions such as LWMO, typhoons, torrential rain and black hole approaches into some dreadful destination ports), I have come to realise and appreciate the benefits of PAPI. Consider:
1. Erroneous T-VASIS indications are thought to have been the cause of some aircraft accidents. PAPIs don’t seem to have these same erroneous indications. Therefore this change may save your life sometime down the track.
2. PAPIs now appear to be the accepted International standard. There is a lot to be said for the enhancement of safety by standardisation of approach facilities. T-VASIS can now only be rarely found in some third world countries…and (including?) Australia.
If nothing else, if you are going international, you would do well to teach yourself to discriminate between shades of pink!
1. Erroneous T-VASIS indications are thought to have been the cause of some aircraft accidents. PAPIs don’t seem to have these same erroneous indications. Therefore this change may save your life sometime down the track.
2. PAPIs now appear to be the accepted International standard. There is a lot to be said for the enhancement of safety by standardisation of approach facilities. T-VASIS can now only be rarely found in some third world countries…and (including?) Australia.
If nothing else, if you are going international, you would do well to teach yourself to discriminate between shades of pink!
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Blip. I totally agree.
I feel that we will see this far inferior system replacing T-Vasis all over the country. The T-Vasis is unquestionably the most effective indicator of any I have seen worldwide.
The red/white vasis is also far better than PAPI.
I confess to being partially colourblind, although obviously within limits, and, particularly in bright daylight, the indication is totally useless outside about 5 miles.
I use FMS, mental arithmetic and judgement to put me on the right slope, then confirm it with the PAPI when I get close enough.
Great system.
I feel that we will see this far inferior system replacing T-Vasis all over the country. The T-Vasis is unquestionably the most effective indicator of any I have seen worldwide.
The red/white vasis is also far better than PAPI.
I confess to being partially colourblind, although obviously within limits, and, particularly in bright daylight, the indication is totally useless outside about 5 miles.
I use FMS, mental arithmetic and judgement to put me on the right slope, then confirm it with the PAPI when I get close enough.
Great system.
Thread Starter
FlexibleResponce they're fair points you raise.
I did my time, flying international operations for a little over five years. For me, flying overseas now must involve a glass of wine in hand and a good movie.
And before anyone says it, yes I have seen the T-VASIS indicate two dots fly up and two dots fly down simultaniously, and is susceptible to refraction through fog/mist etc. So I acknowledge that it is not a perfect system as it is but at least you know when it is giving you eroneous information.
May I suggest to the powers that be that the PAPI use Green and Red lights rather than White (Pink) and Red!
I did my time, flying international operations for a little over five years. For me, flying overseas now must involve a glass of wine in hand and a good movie.
And before anyone says it, yes I have seen the T-VASIS indicate two dots fly up and two dots fly down simultaniously, and is susceptible to refraction through fog/mist etc. So I acknowledge that it is not a perfect system as it is but at least you know when it is giving you eroneous information.
May I suggest to the powers that be that the PAPI use Green and Red lights rather than White (Pink) and Red!
Last edited by Blip; 23rd Jul 2005 at 08:23.
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I grew up with VASIS but havent seen any for years. Not sure I could interpret them anymore!!!
Papi are better, I feel, for Instrument approaches, whereas VASI is far superior for visuals.
PAPIs also need some warm up time before use. If they have just been switched on for you, you can see 4 pinks no matter where on the slope you are.
I guess its an indication that the world is expecting everyone to do an instrument approach!
Papi are better, I feel, for Instrument approaches, whereas VASI is far superior for visuals.
PAPIs also need some warm up time before use. If they have just been switched on for you, you can see 4 pinks no matter where on the slope you are.
I guess its an indication that the world is expecting everyone to do an instrument approach!
I confess to being partially colourblind, although obviously within limits, and, particularly in bright daylight, the indication is totally useless outside about 5 miles.
In poor viz, you may as well not have them. T-Vasis is far more superior, but realistically due to cost considerations we are stuck with it.
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I much prefer T-VASIs to PAPIs, and I am not the slightest bit colour-blind.
For one thing, T-VASIs are pretty fool-proof and it's so bleeding obvious what they're getting at that. PAPIs, on the other hand, can be a bit hard to spot in terms of the colour changes (especially some of the cheapo dodgy installations that seem entirely consisting of suble pink than red or white, no matter whether you are high or low or on the glideslope).
There is also a danger in transitioning from T-VASI to PAPI unless the change is clearly brought to the pilot's attention (I know we should check, but still, anyway, there are those who don't, or plain forget!). "It's a T-VASI, so I'm on the right track. Oh DAMN! It's a PAPI and now I'm hopelessly high!!" can happen.
Anyway... I think PAPI is a backward step.
From the human factors perspective, T-VASI is far superior IMO.
For one thing, T-VASIs are pretty fool-proof and it's so bleeding obvious what they're getting at that. PAPIs, on the other hand, can be a bit hard to spot in terms of the colour changes (especially some of the cheapo dodgy installations that seem entirely consisting of suble pink than red or white, no matter whether you are high or low or on the glideslope).
There is also a danger in transitioning from T-VASI to PAPI unless the change is clearly brought to the pilot's attention (I know we should check, but still, anyway, there are those who don't, or plain forget!). "It's a T-VASI, so I'm on the right track. Oh DAMN! It's a PAPI and now I'm hopelessly high!!" can happen.
Anyway... I think PAPI is a backward step.
From the human factors perspective, T-VASI is far superior IMO.
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Bloody pilots!
Who the hell do you think you are?!? PAPI is much superior because everyone else has it. If ICAO says it's good, then it must be good. I suggest that everyone here repeat that ten times... "If ICAO says it's good, then it must be good"
And if the government decides it's a good idea to spend a big chunk of money on ripping out perfectly good T-VASAI (plural of T-VASI), then it must be a good idea because the government knows....no, hang on, let me get back to you on that one....
Who the hell do you think you are?!? PAPI is much superior because everyone else has it. If ICAO says it's good, then it must be good. I suggest that everyone here repeat that ten times... "If ICAO says it's good, then it must be good"
And if the government decides it's a good idea to spend a big chunk of money on ripping out perfectly good T-VASAI (plural of T-VASI), then it must be a good idea because the government knows....no, hang on, let me get back to you on that one....
Both systems are VISUAL approach systems and it doesn't matter whether you fly an ILS in cloud to say 3 miles and become fully visual either on a T-VASIS or a PAPI the resulting visual angle of approach is the same. So it has nothing to do with coming into the view of the VASIS from an instrument approach or not.
When PAPI was first mooted many years ago, it was argued correctly that PAPI indications were colour dependant and thus wide open to the pink or vague colour difference under certain atmospheric conditions that was mentioned in the early posts. In fact the PAPI is still a very accurate visual aid, providing that it is serviced correctly - and that is the problem.
Like all VASIS types around Australia, once the initial installation is completed and a commissioning flight test by a dedicated aircraft is completed, there are no more scheduled flight tests unless pilots submit a formal complaint with full details of what they saw.
Even then, although airport Maintenance staff may go out to the VASIS and have a look for crook lamps, snakes, long grass or earth movement etc, there will not necessarily be a flight test arranged due to the cost of flying the dedicated navaid test aircraft to wherever.
In the old days when the Department of Civil Aviation Flying Unit F28, F27 or DC3 were on tap, a crew would be despatched to re-test the VASIS at tax payer's expense. VASIS was also subject to routine annual flight tests. Now that a private operator has the contract for navaid calibration work, the tendency is to cut costs to an absolute minimum and therefore the services for a dedicated VASIS flight test by the current contractor is seldom called for.
The upshot of all this is that it is left to pilots to officially notify ATC or the appropriate authority that runs the airport if they perceive a problem. A certain degree of colour blindness is allowed for pilots for purposes of holding an ATPL, but the downside of that is some pilots may experience occasional difficulty in interpreting PAPI signals. It was no problem with T-VASIS unless you were in a gross 1.9 degree undershoot in the red, but then the three fly up lights had already given you advance warning of an impending undershoot.
While I personally have always liked T-VASIS and prefer it to PAPI for several reasons, the fact remains that it is more expensive to maintain. The atmospheric conditions that can give rise to erroneous VASIS light signals also can affect PAPI. Vague pinkish colours rather than bright red lights can cause confusion.
When PAPI was first mooted many years ago, it was argued correctly that PAPI indications were colour dependant and thus wide open to the pink or vague colour difference under certain atmospheric conditions that was mentioned in the early posts. In fact the PAPI is still a very accurate visual aid, providing that it is serviced correctly - and that is the problem.
Like all VASIS types around Australia, once the initial installation is completed and a commissioning flight test by a dedicated aircraft is completed, there are no more scheduled flight tests unless pilots submit a formal complaint with full details of what they saw.
Even then, although airport Maintenance staff may go out to the VASIS and have a look for crook lamps, snakes, long grass or earth movement etc, there will not necessarily be a flight test arranged due to the cost of flying the dedicated navaid test aircraft to wherever.
In the old days when the Department of Civil Aviation Flying Unit F28, F27 or DC3 were on tap, a crew would be despatched to re-test the VASIS at tax payer's expense. VASIS was also subject to routine annual flight tests. Now that a private operator has the contract for navaid calibration work, the tendency is to cut costs to an absolute minimum and therefore the services for a dedicated VASIS flight test by the current contractor is seldom called for.
The upshot of all this is that it is left to pilots to officially notify ATC or the appropriate authority that runs the airport if they perceive a problem. A certain degree of colour blindness is allowed for pilots for purposes of holding an ATPL, but the downside of that is some pilots may experience occasional difficulty in interpreting PAPI signals. It was no problem with T-VASIS unless you were in a gross 1.9 degree undershoot in the red, but then the three fly up lights had already given you advance warning of an impending undershoot.
While I personally have always liked T-VASIS and prefer it to PAPI for several reasons, the fact remains that it is more expensive to maintain. The atmospheric conditions that can give rise to erroneous VASIS light signals also can affect PAPI. Vague pinkish colours rather than bright red lights can cause confusion.
Moderate, Modest & Mild.
IMO - the Australian T-Vasis provides the pilot with information that is calibrated more accurately than PAPI - but do we REALLY need this info?
PAPI is the worldwide standard now - as a matter of fact, the majority of non-Australian, international pilots flying into OZ probably have NO IDEA how to interpret the T-Vasis.
And so, Australia is merely adjusting to conform to the majority consensus..PAPI.
Yes, T-Vasis was great while we had it - it also had it flaws though...I've seen full fly up/fly down indications in ground fog conditions (in Hobart)...but the majority opinion - be it for $$$'s, or simply non-exposure to the Australian T-Vasis - is for PAPI.
(Besides, how could you expect Septics to count any more than the number of digits on 1 hand for ANYTHING??!!!)
PAPI is the worldwide standard now - as a matter of fact, the majority of non-Australian, international pilots flying into OZ probably have NO IDEA how to interpret the T-Vasis.
And so, Australia is merely adjusting to conform to the majority consensus..PAPI.
Yes, T-Vasis was great while we had it - it also had it flaws though...I've seen full fly up/fly down indications in ground fog conditions (in Hobart)...but the majority opinion - be it for $$$'s, or simply non-exposure to the Australian T-Vasis - is for PAPI.
(Besides, how could you expect Septics to count any more than the number of digits on 1 hand for ANYTHING??!!!)
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I cut my Ops teeth out on the airfield at Heathrow, over 25 years ago. At that time, we had VASIS installed on 5 out of 6 approaches. We had a weekly routine with the engineers, calibrating each box of each set. This took a crew of 5 or 6 people a complete morning. The results were less than satisfactory from an accuracy point of view; the first 747 movement would blast the boxes and we'd have to go and check them again, if anyone complained. Far from satisfactory! In the early eighties, a PAPI replacement programme was started. The units are much more blast-proof and stay in calibration very well. We also had mega problems with pink emissions from the units and went to 30 min warm-up periods then eventually permanent heaters being fitted to alleviate this problem. The units now are very reliable and accurate and I for one wouldn't DREAM of going back to VASIS.
You pilots want us Ops types to give you the best, most reliable, fail-safe aids that we can. It isn't just a money thing- from my point of view anyway.
The only downside for me with PAPI is the aforementioned business with B747 eye-height; it does mean that everyone else touches further down the runway than necessary. I've advocated a 5-light setup in the past, so you can choose a nearer or further aiming point, but someone's bound to choose the wrong one!
Incidentally, each 'light' consists of several lamps so that some lamp failures can occur but the system remains usable - not always the case with VASI.
Stick with it - it's worth the hassle!
Cheers,
The Odd One
You pilots want us Ops types to give you the best, most reliable, fail-safe aids that we can. It isn't just a money thing- from my point of view anyway.
The only downside for me with PAPI is the aforementioned business with B747 eye-height; it does mean that everyone else touches further down the runway than necessary. I've advocated a 5-light setup in the past, so you can choose a nearer or further aiming point, but someone's bound to choose the wrong one!
Incidentally, each 'light' consists of several lamps so that some lamp failures can occur but the system remains usable - not always the case with VASI.
Stick with it - it's worth the hassle!
Cheers,
The Odd One
...still single
Repeat this to yourself 10 times :
1 - "most pilots on pprune think VASIS is better"
2- "PAPI is cheaper than VASIS"
I am happy to repeat your statement :
"If ICAO says it's good, then it must be good". Sure PAPI might be "good enough" for ICAO but still not be better than VASIS (as most pilots agree). PAPI is also cheaper to install, so this might be part of the reason ICAO choose PAPI.
PAPI might be more "cost effective", but not the best means.
1 - "most pilots on pprune think VASIS is better"
2- "PAPI is cheaper than VASIS"
I am happy to repeat your statement :
"If ICAO says it's good, then it must be good". Sure PAPI might be "good enough" for ICAO but still not be better than VASIS (as most pilots agree). PAPI is also cheaper to install, so this might be part of the reason ICAO choose PAPI.
PAPI might be more "cost effective", but not the best means.
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OddOne,
Please re-read your instruction manuals before addressing a thread dealing with T-VASIS on the basis of your experience with VASIS. Birds of quite different feather. Speaking as a sometime calibrator, T-VASIS, whether in a military or civvy environment, rarely needed much adjustment at the six-monthly.
Gru
Please re-read your instruction manuals before addressing a thread dealing with T-VASIS on the basis of your experience with VASIS. Birds of quite different feather. Speaking as a sometime calibrator, T-VASIS, whether in a military or civvy environment, rarely needed much adjustment at the six-monthly.
Gru
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Well, I'm staggered that we're even having this discussion!
T-Vasis versus Papi, it must be obvious to any practising pilot who's been around for 20 or 30 yrs, and has used both, which is the best system! ( Clue: it starts with T )
By the way, I think the New Zealanders actually invented it , didn't they?
T-Vasis versus Papi, it must be obvious to any practising pilot who's been around for 20 or 30 yrs, and has used both, which is the best system! ( Clue: it starts with T )
By the way, I think the New Zealanders actually invented it , didn't they?
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Sort of makes you wonder why they dont actually put in an ILS for MEL Rwy 34.
Any reasons apart from the obvious one being cost??
Any reasons apart from the obvious one being cost??
Normally just blows 40 b@stards and thats it.
Perhaps the T vasis are being ditched cos you cant get the spares anymore.After all who else uses the things. I can also say that 90% of international pilots will interperet the things the wrong way,so they cant be that clever!
Outofsynch. If the PAPI needs a warm up period before giving reliable signals, you would think that Air Services would warn of this via AIP. It it was a significant problem then surely PAL actuation would prove insufficient time for the lamps to warm up in order to prevent pink rather than red lights.
Occasional single or two lamp failure on a VASIS box makes almost no difference to the integrity. The light source appears a little dimmer, that's all. However if one complete box goes out of action due a major electrical problem, then that can quite misleading. Of course one box u/s on a PAPI would be misleading, too.
Occasional single or two lamp failure on a VASIS box makes almost no difference to the integrity. The light source appears a little dimmer, that's all. However if one complete box goes out of action due a major electrical problem, then that can quite misleading. Of course one box u/s on a PAPI would be misleading, too.