WIZZ AIR Skiathos vid
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Where does the perception that risk is increased on wet runways come from; the published landing distances show adequate margin.
Slippery when wet due to rubber deposits,
Dust gathered during dry days turn into a slippery cladding when rain comes along
Even disregarding those possibilities, if a runway is of fixed length and dry numbers give you a small margin, the wet numbers will give you even less margin. It's relevant when we speak of Skiathos.
If, say, 50 m margin is adequate is a subjective.
The discussion on PAPI, #142 onwards is intriguing; as is the continuing views of ‘normal’.
Adding to the PAPI issue, is the setting of the angular change between white and red, which adjusts the sensitivity of the aid; e.g. crossing the road 3R 1W - a ‘minor’ (unseen) transgression is a small height difference on a ‘tight’ setting, but a larger height difference on a ‘wide’ setting. Not forgetting that this relates to the height of the cockpit, and not the wheel height judged by video.
If aiming to land at the normal touchdown point is safe, then why advise to aim short of normal on a ‘wet’ runway, if it is ‘less safe’, (increase undershoot risk vs perceived increased risk in landing distance for a wet runway). ‘Wet’ is one view, ‘contaminated’ another, but not the same.
This is another SOP double bind; the procedure makers move responsibility down to the crew - no right answer, except by judged outcome.
Where does the perception that risk is increased on wet runways come from; the published landing distances show adequate margin.
[One view is that wet runways landing distances do not always have equivalent distance margins as for dry - a view which I subscribe to, debatable elsewhere - , but not requiring a change in aiming point.]
Adding to the PAPI issue, is the setting of the angular change between white and red, which adjusts the sensitivity of the aid; e.g. crossing the road 3R 1W - a ‘minor’ (unseen) transgression is a small height difference on a ‘tight’ setting, but a larger height difference on a ‘wide’ setting. Not forgetting that this relates to the height of the cockpit, and not the wheel height judged by video.
If aiming to land at the normal touchdown point is safe, then why advise to aim short of normal on a ‘wet’ runway, if it is ‘less safe’, (increase undershoot risk vs perceived increased risk in landing distance for a wet runway). ‘Wet’ is one view, ‘contaminated’ another, but not the same.
This is another SOP double bind; the procedure makers move responsibility down to the crew - no right answer, except by judged outcome.
Where does the perception that risk is increased on wet runways come from; the published landing distances show adequate margin.
[One view is that wet runways landing distances do not always have equivalent distance margins as for dry - a view which I subscribe to, debatable elsewhere - , but not requiring a change in aiming point.]
When a decision to alter the procedure due to a perception of a specific threat arises, then the answer is to revisit what it being attempted. It should not be up to the pilot to use an untrained, and unapproved technique in order to satisfy perceptions of risk, there be dragons in that direction, and the liability reverts to the crew, well, they are always the first at the accident site anyway.
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Were You trained for this
If the operation necessitates anything other than normal operations with more restrictive tolerances, then the public safety is being compromised by the workaround. We used to operate a baby B747 into an interesting airport, and there were very specific criteria for completing a touchdown, but the flight path, MEHT/TCH and Vapp were not altered, it was an exactly standard flight profile, but with very specific decision tolerances.
When a decision to alter the procedure due to a perception of a specific threat arises, then the answer is to revisit what it being attempted. It should not be up to the pilot to use an untrained, and unapproved technique in order to satisfy perceptions of risk, there be dragons in that direction, and the liability reverts to the crew, well, they are always the first at the accident site anyway.
When a decision to alter the procedure due to a perception of a specific threat arises, then the answer is to revisit what it being attempted. It should not be up to the pilot to use an untrained, and unapproved technique in order to satisfy perceptions of risk, there be dragons in that direction, and the liability reverts to the crew, well, they are always the first at the accident site anyway.
If not, why did you do it. Most of the times, “Normalization of Deviance “ sets in a particular operation ( if it’s challenging) and most crews do it even though not specifically trained for it.
If there’s FOQA , the crew should be called in and the operation revisited.
For landing on Wet /Contaminated Runways, SAFO 19003 ( FAA ) is important reading.
Confusious, Vref
Fly the speed which was used to determine performance.
- - -
This is an acceptable airport for normal procedures, don't invent or address problems where there are none.
The point of interest is the relationship between touchdown markings, PAPI glide-slope origin, and the start of the runway hard surface, and an apparent difference in conventional definition - relationship between these and a ‘threshold’.
The safety issue is with the people on the road, and uncontrolled vehicles; … and any risk inappropriately generated by false perceptions based in videos.
Re SAFO 19003,
The FAA appears lag ICAO post TALPA; ‘for equivalent safety in older aircraft or when FOLD is not avaiable, the wet (factored dry 1.67 +15%) is now 2.2.’
ICAO Doc 10064 - Aeroplane Performance Manual Appendix 5
and
Appendix 7 ‘Landing on length limited runways’.
“Fly correct approach speed”
“Use correct aiming point”
Fly the speed which was used to determine performance.
- - -
This is an acceptable airport for normal procedures, don't invent or address problems where there are none.
The point of interest is the relationship between touchdown markings, PAPI glide-slope origin, and the start of the runway hard surface, and an apparent difference in conventional definition - relationship between these and a ‘threshold’.
The safety issue is with the people on the road, and uncontrolled vehicles; … and any risk inappropriately generated by false perceptions based in videos.
Re SAFO 19003,
The FAA appears lag ICAO post TALPA; ‘for equivalent safety in older aircraft or when FOLD is not avaiable, the wet (factored dry 1.67 +15%) is now 2.2.’
ICAO Doc 10064 - Aeroplane Performance Manual Appendix 5
and
Appendix 7 ‘Landing on length limited runways’.
“Fly correct approach speed”
“Use correct aiming point”
Only half a speed-brake
The amining point markers at Skiathos is about 150 m from the threshold. Runways with a length above 2400 m (is it?) has the aiming point markers at 450 m past the threshold. The threshold crossing heights can't be the same, if your objective is to land at the aiming point. The performance in-flight calculations for Actual Landing Distance from 50 ft doesn't care about the runway length.
The aiming point markers are the same thing. If the painted in the wrong place, an AFM-like landing cannot be flown towards them. On a 3°/50' standard AFM or ILS profile the RA 'over numbers' height is 30 feet. The LDA and LDR + FLD + OLD + RLD should be satisfied with their inherent margins as applicable using that technique which should be the same no matter the landing distance (fact to me, but respecting the reality that HF will phase shift that in reality).
Should you choose to aim for the 150 marker the resulting gear clearance is 8
Other words: A pilot taking his 320 into a runway so short the aiming marker is unusable for his landing geometry should know not to use it. Was that covered in my short runway training - definitely not. If then, upon seeing the underrun and feeling comfortable (that has not bitten anyone ever, right), the instincts take over and he cuts it short into the first marker - then by all means that is how life works.
Similar but opposite direction, keping the ILS centered to about 100 feet RA and then flying the landing towards 400 mtrs aiming markers + PAPI at Palma / Manchester / Fumicino / Dubai is susceptible to building a habit of a 2 degree profile at 66 feet over threshold (RA 50).
Bring that style to JSI and there will be a massive 'does not compute' moment overloading the normal routines. The rest is videotaped above.
Saying short runways need to be landed short or the aim point markers (at varying distances) should be used to schedule the landing trajectory - sorry sir. I don't mind if you do and trust your skill to make it (repeatedly) but the standard of explainign to others or teaching need to be better than that.
Yet so far the key lesson was completely missed, save for one post.
Why the crew did not go around?! Not whether they should but why they did not. I think anyone here can learn a bit if we dissect that.
Last edited by FlightDetent; 14th Aug 2022 at 16:08.
I think they didn’t go around because “out of the window” it didn’t look that far out. Maybe they felt it “a little low”, but well with in the realms of there or there abouts. That’s what this airport does, and that’s why the vast majority of pilots cannot fly a 3 degree profile to touchdown. They will always be low.
On just about every approach I have flown, or I have seen flow (by pilots of much greater talent than me) 50ft call occurs over the sea, 30ft over the beach, 20ft over the threshold. I think this Wizz crew were maybe 10-15ft too low.
Also, only one of the pilots would have undergone any training for this place, and only one of the pilots would be authorised to operate in here. That would be the Captain. It may well have been the first time the FO had ever seen the place, or anything like it.
On just about every approach I have flown, or I have seen flow (by pilots of much greater talent than me) 50ft call occurs over the sea, 30ft over the beach, 20ft over the threshold. I think this Wizz crew were maybe 10-15ft too low.
Also, only one of the pilots would have undergone any training for this place, and only one of the pilots would be authorised to operate in here. That would be the Captain. It may well have been the first time the FO had ever seen the place, or anything like it.
Only half a speed-brake
In the first 2 pages or thereabouts, you did an excellent summary of the curved mirrors this approach environment has for the visitor. Not sure if listed already but elevation might be relevant too, it is 39 feet.
My thinking is as you come into the bay the nicely scalloping waterline in the peripheral gives you a reasonable perception of height - over the water. The runway is narrow which would reinforce the illusion of being (still) high, the sense of depth is just not there looking straight forward
And then the runway, hidden in plain sight until late, jumps up towards you. It is even higher than the road level.
My thinking is as you come into the bay the nicely scalloping waterline in the peripheral gives you a reasonable perception of height - over the water. The runway is narrow which would reinforce the illusion of being (still) high, the sense of depth is just not there looking straight forward
And then the runway, hidden in plain sight until late, jumps up towards you. It is even higher than the road level.
Last edited by FlightDetent; 14th Aug 2022 at 16:10.
Only half a speed-brake
Another observation:
The 330 mtrs aiming point as marked with the blue line would result in MLG touch at 400-450 m distance as per AFM, leaving 1120 m of braking pavement ahead.
Touchdown geometry (not on the FCOM graphics above - numbers for A320):
No-flare brings the MLG to ground 130 m ("B") short of the aiming point point whereas 'typical' landing touches about 100 m past the aiming point (430m let's say). A cropped half-flare of 130 meters instead of optimal 230 will land the plane exactly at the aiming point.
Going for the MARKERS with such short flare, which seems to be the most frequent result from the good videos, yields an additional 280 m for braking =>> 1400 v.s. 1120. A marked difference, also giving you the chance utilize the uphill slope.
What about the wheel clearance? (significantly corrected from own post above).
Aiming at markers (150 m) gives around 8 feet.
Threshold is displaced by 60 m providing additional 10.
Ground loop for turning has another 50 mtrs for +8 more.
= 27 ft compared to theoretical 31, not bad.
If the pilot eye ignores the painted lines, crossing the pavement edge while aiming at the makrers (+ invisible PAPI) is not critical and will feel somewhat normal. From a 3 deg profile, that is. Of course, the big squares are 260 m from the grass.
Last edited by FlightDetent; 15th Aug 2022 at 04:39.
Only half a speed-brake
I was never trained where to aim for, just assumed and went for the big squares and PAPIs (400 mtrs at 98 % of my airports of first 8 years).
Hope nobody teaches using the aiming piont markers located at 150 as that will result in 8 feet wheel clearance. (no-flare geometry)
If you or I end up doing exactly that (at absence of active understandig what the location and meaning of the markers is), here at JSI the wheel pass approx 27 feet over the edge of the paved surface (turning loop). Which actually covers for the compromised aiming point by the virtue of airport design.
The road itself is little further away and has lower elevation, please check.
Hope nobody teaches using the aiming piont markers located at 150 as that will result in 8 feet wheel clearance. (no-flare geometry)
If you or I end up doing exactly that (at absence of active understandig what the location and meaning of the markers is), here at JSI the wheel pass approx 27 feet over the edge of the paved surface (turning loop). Which actually covers for the compromised aiming point by the virtue of airport design.
The road itself is little further away and has lower elevation, please check.
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I think the attitude from certain training departments that all landings should be the same and all runways should be treated the same is a) choosing to be naive to the point of negligence and b) completely and utterly ignores the human factor of the pilot looking out the window and actually experiencing these runways on a daily basis. It brings to mind SOPs that are routinely ignored or worked around by crew but yet the management choose to remain blind to the reality of the situation and ignore the clearly poorly designed/implemented SOP.
If you tell me that landing lightweight, with a ten knot headwind, CAVOK, 3,000+ runway, ops normal should be precisely the same as landing up to MLW, contaminated, possibly tailwind, high autobrake required in-flight calculations then you are either telling porky pies or are genuinely that low-skilled as to not be able to discern/operate as required by the situation.
If you tell me that landing lightweight, with a ten knot headwind, CAVOK, 3,000+ runway, ops normal should be precisely the same as landing up to MLW, contaminated, possibly tailwind, high autobrake required in-flight calculations then you are either telling porky pies or are genuinely that low-skilled as to not be able to discern/operate as required by the situation.
I think the attitude from certain training departments that all landings should be the same and all runways should be treated the same is a) choosing to be naive to the point of negligence and b) completely and utterly ignores the human factor of the pilot looking out the window and actually experiencing these runways on a daily basis.
Only half a speed-brake
Questions, questions...
How much lower than 28 feet (standard) over the red lights do you want to go for a tailwind landing with a 330?
What is the point of deliberately choosing a landing deeper that the normal distance on any day, protecting the tarmac behind you? 3000 meters rwy most likely have a turnoff to take at 1700 meters, don't they.
The training departments by some lucky chance might just know what they are talking about.
And this is why automation will make us all jobless. Because it is configurable and can be improved. Humans as a group cannot. Freshly reliving other people's bad days since 200000 B.c.e.
Imagine, in 2022, professionals screaming out loud they need to fly shorter than expected as a failsafe means of avoiding an undesired state, and how they enjoy flying the plane for extra 15 seconds because this runway is too long anyway.
Here is a thought:
Why did the FAA chose not to follow the ICAO guidance but instead keep aiming markers at 1000' for even the longest runways? (at the same time they do set the PAPIs at 1500' to allow proper visual guidance for the largest incoming craft and protect threshold crossing clearance).
Thought 2:
Because the painting standard for JSI runway length requires the aim point markers at the first position (150 mtrs), to assure CAT near obstacle clearance (8 ft not enough) is actually the reason why the threshold needed to be displaced deeper down the pavement.?
Flare technique differs, no contesting that. The aiming point the pilot choses should not.
Most people probably don't even chose one. Rest assured by the outcome statistics, everyone seems to be doing a good job - again - we may think about it differently but end up doing the same thing.
On the other hand, the language of training needs to be clear and correct. So when we have a bad day the job is still done acceptably.
How much lower than 28 feet (standard) over the red lights do you want to go for a tailwind landing with a 330?
What is the point of deliberately choosing a landing deeper that the normal distance on any day, protecting the tarmac behind you? 3000 meters rwy most likely have a turnoff to take at 1700 meters, don't they.
The training departments by some lucky chance might just know what they are talking about.
And this is why automation will make us all jobless. Because it is configurable and can be improved. Humans as a group cannot. Freshly reliving other people's bad days since 200000 B.c.e.
Imagine, in 2022, professionals screaming out loud they need to fly shorter than expected as a failsafe means of avoiding an undesired state, and how they enjoy flying the plane for extra 15 seconds because this runway is too long anyway.
Here is a thought:
Why did the FAA chose not to follow the ICAO guidance but instead keep aiming markers at 1000' for even the longest runways? (at the same time they do set the PAPIs at 1500' to allow proper visual guidance for the largest incoming craft and protect threshold crossing clearance).
Thought 2:
Because the painting standard for JSI runway length requires the aim point markers at the first position (150 mtrs), to assure CAT near obstacle clearance (8 ft not enough) is actually the reason why the threshold needed to be displaced deeper down the pavement.?
Flare technique differs, no contesting that. The aiming point the pilot choses should not.
Most people probably don't even chose one. Rest assured by the outcome statistics, everyone seems to be doing a good job - again - we may think about it differently but end up doing the same thing.
On the other hand, the language of training needs to be clear and correct. So when we have a bad day the job is still done acceptably.
Last edited by FlightDetent; 15th Aug 2022 at 09:43.
I think the attitude from certain training departments that all landings should be the same and all runways should be treated the same is a) choosing to be naive to the point of negligence and b) completely and utterly ignores the human factor of the pilot looking out the window and actually experiencing these runways on a daily basis. It brings to mind SOPs that are routinely ignored or worked around by crew but yet the management choose to remain blind to the reality of the situation and ignore the clearly poorly designed/implemented SOP.
If you tell me that landing lightweight, with a ten knot headwind, CAVOK, 3,000+ runway, ops normal should be precisely the same as landing up to MLW, contaminated, possibly tailwind, high autobrake required in-flight calculations then you are either telling porky pies or are genuinely that low-skilled as to not be able to discern/operate as required by the situation.
If you tell me that landing lightweight, with a ten knot headwind, CAVOK, 3,000+ runway, ops normal should be precisely the same as landing up to MLW, contaminated, possibly tailwind, high autobrake required in-flight calculations then you are either telling porky pies or are genuinely that low-skilled as to not be able to discern/operate as required by the situation.
Using standard technique and being totally open about rejecting the landing should it not work out is the way to proceed. The videos showing the majority of flights into JSI crossing the road at a reasonable height, doing a “standard landing” and rollout with room to spare shows this.
Part of being a professional pilot is to have the ability to get creative when needed but also to follow SOPs when they have been demonstrated to work.