Stabilzed Approach with white PAPI
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Aterpester,
I understand and agree that Precision approach aids are more precise than visual aids such as papis
If one flies an ILS,the glide slope is the most accurate but Papis should be monitored as well,as they give an easier,less precise guidance than the glide slope at low altitudes.(it was mentioned earlier,that new pilots may find easier to follow the papis in the last 500 feet than the glide)..
If one flies a VNAV app,the papis should also be included in the scan for cross checking(distance versus altitude).
If one flies a Visual, the Papis provide the best guidance when turning final.
If one flies a non precision app (Vor,Ndb),the papis provide the best guidance until distance to threshold is such that the aiming point is clearly identified and followed.
Also, the Papis position (left or right or runway) should always be briefed(especially during non prec.app)as they will give an additional clue that you are aligned with the correct runway.
Knowing if the papis for the runway you will use are calibrated for 747 will give you an extra clue as whether to follow them precisely until approaching the threshold or if an earlier transition to the aiming point is more adequate.
I hope that clarifies my previous posts and general idea on the subject
I understand and agree that Precision approach aids are more precise than visual aids such as papis
If one flies an ILS,the glide slope is the most accurate but Papis should be monitored as well,as they give an easier,less precise guidance than the glide slope at low altitudes.(it was mentioned earlier,that new pilots may find easier to follow the papis in the last 500 feet than the glide)..
If one flies a VNAV app,the papis should also be included in the scan for cross checking(distance versus altitude).
If one flies a Visual, the Papis provide the best guidance when turning final.
If one flies a non precision app (Vor,Ndb),the papis provide the best guidance until distance to threshold is such that the aiming point is clearly identified and followed.
Also, the Papis position (left or right or runway) should always be briefed(especially during non prec.app)as they will give an additional clue that you are aligned with the correct runway.
Knowing if the papis for the runway you will use are calibrated for 747 will give you an extra clue as whether to follow them precisely until approaching the threshold or if an earlier transition to the aiming point is more adequate.
I hope that clarifies my previous posts and general idea on the subject
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VGSIs are invaluable when the approach does not have a DA for the landing runway.
Since you bring up the finer points about VGSIs, it is also important to determine whether there is any restriction to its customary maximum useable distance and angle of coverage especially at night and/or in restricted visibility conditions.
Since you bring up the finer points about VGSIs, it is also important to determine whether there is any restriction to its customary maximum useable distance and angle of coverage especially at night and/or in restricted visibility conditions.
The stabilised approach criteria in my current airline specifically excludes PAPI from the definition in order to allow for approaches not coincident with the PAPI slope.
A case in point is the RWY05 VOR/DME approach at Geneva, which due to terrain is quite a bit higher than the ILS & PAPI. On the VOR/DME correct profile, at the minima, you will have 4 whites on the PAPI - but under our definition this is "stable" and you may continue to a landing.
Interesting about the USA FAA rule regarding touch-down zone. In Australia the company had an SOP about the touch-down zone, but my UK airline seems to ignore it completely in their manuals and operation. A mistake IMHO.
A case in point is the RWY05 VOR/DME approach at Geneva, which due to terrain is quite a bit higher than the ILS & PAPI. On the VOR/DME correct profile, at the minima, you will have 4 whites on the PAPI - but under our definition this is "stable" and you may continue to a landing.
Interesting about the USA FAA rule regarding touch-down zone. In Australia the company had an SOP about the touch-down zone, but my UK airline seems to ignore it completely in their manuals and operation. A mistake IMHO.
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I can't speak to PANS-OPS in this case (which is generally more conservative than TERPs) but such approaches that have straight-in minimums under TERPs cannot exceed a final segment descent gradient of 400 feet per mile (3.77 degrees) to the runway. Once within the distance of VGSI coverage, and visual, an adjustment to capture the VGSI generally won't de-stabilize the approach and has the added benefit of not crossing the threshold excessively high.
Often those types of VOR approaches are offset from the runway so there has to be a lateral maneuver once visual.
A case in point is the RWY05 VOR/DME approach at Geneva, which due to terrain is quite a bit higher than the ILS & PAPI. On the VOR/DME correct profile, at the minima, you will have 4 whites on the PAPI - but under our definition this is "stable" and you may continue to a landing.
Often those types of VOR approaches are offset from the runway so there has to be a lateral maneuver once visual.
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Quote:'Once within the distance of VGSI coverage, and visual, an adjustment to capture the VGSI generally won't de-stabilize the approach and has the added benefit of not crossing the threshold excessively high.
Often those types of VOR approaches are offset from the runway so there has to be a lateral maneuver once visual.'unquote.
I agree.
Having flown to Innsbruck in Austria on B737s,the Loc approach on Rwy 26 would lead you to an MDA,but then a visual segment was required(slight left turn)to intercept the runway centerline.Therefore allowing extra room to lose some altitude and follow the papis once established on final.
Using a VDP would allow a more standard rate of descent at low altitude.
I have never flown to Geneva but I am sure if you do a non precision approach there and continue to the published MAP,you will be high on final,therefore the importance of defining your VDP before the approach and then be able to continue with the same rate to establish on the papis.
Often those types of VOR approaches are offset from the runway so there has to be a lateral maneuver once visual.'unquote.
I agree.
Having flown to Innsbruck in Austria on B737s,the Loc approach on Rwy 26 would lead you to an MDA,but then a visual segment was required(slight left turn)to intercept the runway centerline.Therefore allowing extra room to lose some altitude and follow the papis once established on final.
Using a VDP would allow a more standard rate of descent at low altitude.
I have never flown to Geneva but I am sure if you do a non precision approach there and continue to the published MAP,you will be high on final,therefore the importance of defining your VDP before the approach and then be able to continue with the same rate to establish on the papis.
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As to the RNAV glideslope that leads to a decision altitude that path often provides a more optimum TCH than does a VGSI. Also, in many aircraft the VNAV glideslope can be coupled, thus assuring a stablized descent path to DA if not the threshold. And, in marginal visibility conditions the VGSI can be indistinct in the visual segment, especially in the daytime.
Granted, it looks very precise, especially if you have the same indication as on any precision approach (ILS/GLS), which is the standard on 737s now. However you have to be aware about the pressure and temperature effects on FMC derived glidepath indication. Something that PAPIs do not suffer from.
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Denti:
No doubt that temperature affects Baro VNAV (except for the compensated systems). But, if Baro VNAV is the only IAP certified glidepath option, it is a whole lot better than no vertical path. And, becoming visual at typical minimums its errors are minimal and its better to stay with its stable path than attempting to transition to a VGSI.
Finally, Baro VNAV systems in RNP AR qualified aircraft have to perform to some very tight requirements.
Granted, it looks very precise, especially if you have the same indication as on any precision approach (ILS/GLS), which is the standard on 737s now. However you have to be aware about the pressure and temperature effects on FMC derived glidepath indication. Something that PAPIs do not suffer from.
Finally, Baro VNAV systems in RNP AR qualified aircraft have to perform to some very tight requirements.
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They are very precise as long as the input is correct. However they do suffer a lot from input derived errors. If you have due to pressure change within the time between ATIS-cycles an input error of just one hPa it might make landing on a marginal runway impossible if you follow the GP for too long. Which is the reason why Boeing changed our SOP to only continue visually below any MDA/DA on IAN approaches, the GP is not longer deemed safe below that.
Of course any GP is better than no GP, which is exactly why IAN is such a great tool since it offers a GP for every kind of NP approach, but it remains still a non precision tool with all its limitations. Non-Baro non-ILS precision approaches are something completely different and of course something we hope to see a lot more in the years coming. GLS to CAT I limits is allready operational and we are currently in the certification process to CAT IIIa limits, which makes sense since boeing offers GLS as standard equipment on current aircraft.
Of course any GP is better than no GP, which is exactly why IAN is such a great tool since it offers a GP for every kind of NP approach, but it remains still a non precision tool with all its limitations. Non-Baro non-ILS precision approaches are something completely different and of course something we hope to see a lot more in the years coming. GLS to CAT I limits is allready operational and we are currently in the certification process to CAT IIIa limits, which makes sense since boeing offers GLS as standard equipment on current aircraft.
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Denti:
I don't believe we are speaking of quite the same thing. I am making reference to a Baro VNAV path that is locked in the nav database as part of the instrument approach procedure, not a path constructed by the flight crew.
They are very precise as long as the input is correct. However they do suffer a lot from input derived errors. If you have due to pressure change within the time between ATIS-cycles an input error of just one hPa it might make landing on a marginal runway impossible if you follow the GP for too long. Which is the reason why Boeing changed our SOP to only continue visually below any MDA/DA on IAN approaches, the GP is not longer deemed safe below that.
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I accept that this might be deamed a slight digretion, but I do so anyway. Firstly I have to assume that 3 reds or 3 whites = .25 degree deviation from 3. Thus if you are JUST on 4 whites you are 0.5 degrees from 3 = 3.5 and JUST on 4 reds = 2.5 degress. There is an airfield I frequent where the PAPI's for the circling rwy are set at 2.5 degrees. Our circling procedure is designed to roll you out on finals at 3 degrees. The circling MDA could be as low as 400' agl. & the vis 2400m. The landing gate is 300' and for SOP's you have to be 3 reds or 3 whites at worst. You roll round on finals at MDA and min vis. You see 4 whites. You've got 100' to make the correction, but not at >1000fpm. It's all workable, but it gives the F/O as PM a fright unless you brief it. One solution is to extend the downwind by 5secs to create 3 whites at worst.
However, back to points raised above; you roll out stable on 3 degress, constant aiming point, constant speed, constant power all correct for 3 degrees, but 4 whites. At first it is confusing. Should PM call a G/A? That's their dillema.
Equally, 4 reds becomes a G/A which at some point must transit through 2 whites 2 reds i.e. correct Glide path; so why not make a sensible adjustment rather than a mandatory G/A. Surely Mk.1 eyeball can tell how low you really are, unless of course there is hight ground descending in the undershoot. The same true for 4 whites, Mk.1 eyeball. Could it be that most C.P's don't trust visual judgements anymore? And what would you do on minimum fuel at MDA at a non-radar airfield?
All I'm trying to say is perhaps the answer to the original question is not so red & white. As is much of aviation. We've just been brainwashed into thinking so.
However, back to points raised above; you roll out stable on 3 degress, constant aiming point, constant speed, constant power all correct for 3 degrees, but 4 whites. At first it is confusing. Should PM call a G/A? That's their dillema.
Equally, 4 reds becomes a G/A which at some point must transit through 2 whites 2 reds i.e. correct Glide path; so why not make a sensible adjustment rather than a mandatory G/A. Surely Mk.1 eyeball can tell how low you really are, unless of course there is hight ground descending in the undershoot. The same true for 4 whites, Mk.1 eyeball. Could it be that most C.P's don't trust visual judgements anymore? And what would you do on minimum fuel at MDA at a non-radar airfield?
All I'm trying to say is perhaps the answer to the original question is not so red & white. As is much of aviation. We've just been brainwashed into thinking so.
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I don't believe we are speaking of quite the same thing. I am making reference to a Baro VNAV path that is locked in the nav database as part of the instrument approach procedure, not a path constructed by the flight crew.
Baro VNAV still relies on baro settings and only can be as precise as those. And baro settings are inherently inprecise, unlike purely geometrical approaches like GLS, MLS or ILS. One hPa equals roughly 30ft in height difference at sea level and that is something you will have quite often during rapidly changing conditions. Crossing the threshold at 80 ft (50 plus 30 for one hPa) will increase your landing distance with picture perfect flying by around 200m in a 737, which on a marginal runway could be outside limits (mandatory GA). That is why boeing advised us that the database derived glidepath might not be a good idea to follow below MDA/DA and that segment should be flown visually only, GPWS "glideslope" alerts can then be ignored as they are very common.
Don't get me wrong. Baro VNAV is a nice tool, but one has to be aware of its limits.
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Denti:
The chairman of the FAA/Industry performance based navigation committee (the PARC) is a Boeing engineer. Also, there is another Boeing engineer who represents Boeing on the PARC. It they have discussed this recommendation to not use the database BARO VNAV glidepath below DA, I must have slept through it.
It's now on my question list.
The chairman of the FAA/Industry performance based navigation committee (the PARC) is a Boeing engineer. Also, there is another Boeing engineer who represents Boeing on the PARC. It they have discussed this recommendation to not use the database BARO VNAV glidepath below DA, I must have slept through it.
It's now on my question list.
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Yup, should be interesting. As i said, boeing required a training change to only fly visually below MDA/DA if using Baro VNAV from my company. By the way, it is also very interesting to see the vertical ANP which is constantly displayed on a 737. Haven't seen any value smaller than 40 feet yet which seems to say the same thing as the boeing requirement.
By the way, you might ask them why they are not going for GBAS instead? Covers 50 precision approaches up to CAT IIIb capability within 25 NM around the station, one station costs less than a single VOR.
By the way, you might ask them why they are not going for GBAS instead? Covers 50 precision approaches up to CAT IIIb capability within 25 NM around the station, one station costs less than a single VOR.
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Denti:
I know the answers to that one, at least for the FAA jurisdictions and the U.S. carriers.
1. The FAA is overwhelmed trying to get WAAS become an effective program for other than week-end light tin. Also, their rudder is broken on their NextGen "ship."
2. The airlines can't afford Boeing's or Airbus high, high prices for any avionics retrofits.
By the way, you might ask them why they are not going for GBAS instead? Covers 50 precision approaches up to CAT IIIb capability within 25 NM around the station, one station costs less than a single VOR.
1. The FAA is overwhelmed trying to get WAAS become an effective program for other than week-end light tin. Also, their rudder is broken on their NextGen "ship."
2. The airlines can't afford Boeing's or Airbus high, high prices for any avionics retrofits.
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Hmm, doesn't sound good then. However, at least on 737s GLS is standard equipment if you get new ones which i think quite a few US airlines do. Shame to let it go to waste except for that one test installation in Memphis. Well, over here in the old world WAAS won't be approved for precision approaches soon, and certainly not for CAT II or higher.
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VGSI and ILS are not coincident
What does this mean, I was told that if you are fully coupled to an ILS this approach would take you just short of the runway threshold, I need a reference where I can look this up. Thanks
Jax
Look at the back side of the Jepp Airport Chart (10-9), there is a listing of all the distances--Glide Slope touchdown point is about 1300'-1500' feet from the threshold, TCH on the GP is around 45'-55', so where did you learn that a coupled ILS touches short of the pavement?
The electronic and visual paths may not coincide because that are not collocated on the runway side.
GF
Look at the back side of the Jepp Airport Chart (10-9), there is a listing of all the distances--Glide Slope touchdown point is about 1300'-1500' feet from the threshold, TCH on the GP is around 45'-55', so where did you learn that a coupled ILS touches short of the pavement?
The electronic and visual paths may not coincide because that are not collocated on the runway side.
GF
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There are really only two things that matter when it comes to the final apch and landing: Where do you want your wheels to touch the ground, and at what speed? Boeing says 1.000ft from threshold, at Vref. That is all you need to know. As long as your ROD does not trigger the EGPWS and your colleague's gluteux maximus are not excessively flexed and still in contact with the seat, you should not worry much about the PAPI, as it usually intersects the rwy 1.000-1500ft down the rwy (and then you must flare).
B737 FCTM p.6.6 v.June2010: "The PAPI may safely be used with respect to threshold height, but may result in landing further down the runway."
Find your aimpoint and make the aircraft fly towards it at the correct speed. Basic piloting skills.
My point? If the chief pilot says you MUST fly PAPI down to 50ft in order to be stabilised - show him the OM page where it says that safety is always priority #1. I have seen sooo many pilots struggle to fly that damn PAPI all the way down, working the controls like a damn foosball game and completely forgetting all their basic PPL skills of pitch, power and aimpoint. The flight path usually ends up resembling the path of a sewing machine pin, ending in a grand last-second panic "adjustment" to get back up on the PAPI. This adjustment is usually too aggressive, and we end up whizzing past the PAPI with excess speed and lots of runway behind us. Then you add a limited, slippery runway to that. Aimpoint aimpoint aimpoint and then slam that sucker down before you set a new world record in floating.
B737 FCTM p.6.6 v.June2010: "The PAPI may safely be used with respect to threshold height, but may result in landing further down the runway."
Find your aimpoint and make the aircraft fly towards it at the correct speed. Basic piloting skills.
My point? If the chief pilot says you MUST fly PAPI down to 50ft in order to be stabilised - show him the OM page where it says that safety is always priority #1. I have seen sooo many pilots struggle to fly that damn PAPI all the way down, working the controls like a damn foosball game and completely forgetting all their basic PPL skills of pitch, power and aimpoint. The flight path usually ends up resembling the path of a sewing machine pin, ending in a grand last-second panic "adjustment" to get back up on the PAPI. This adjustment is usually too aggressive, and we end up whizzing past the PAPI with excess speed and lots of runway behind us. Then you add a limited, slippery runway to that. Aimpoint aimpoint aimpoint and then slam that sucker down before you set a new world record in floating.
