Do you really trust that wet runway performance data

[pelmet]

To show an example of how a poster can be giving you bad information......

Last year I made reference to a Safety Alert For Operators(SAFO 15009) in this thread. It has very important information mentioning that landing distances in the aircraft performance manuals should be increased under certain conditions such as during moderate to heavy rain. Rockie was insistent that this SAFO was no longer applicable because it had pre-dated implementation of TALPA(even though it was still on the FAA website and even though an FAA inspector from the Air Carrier Division of the FAA confirmed to me that it was still applicable as seen earlier in this thread). In fact, this poster was giving you very bad information.

These are only some of the ridiculous responses that were given by him as his argument...

I can't explain why the FAA has on their website a SAFO recommendation that has been superceded by the TALPA-ARC recommendations - now regulation. Maybe you should ask them.

Check the dates on your documents versus the TALPA regulation implementation date Pelmet. The ones you're quoting are at least a year before the implementation of TALPA and do not even mention it.

Really...stop. Betraying yourself as a moron is not worth another pointless argument with me.

Or...continue. This should be good...

And each time you ask the same question over again despite getting the answer you betray how little you know about wet runways. Do I need to repeat the answer for a third (or was it fourth) time?

Your SAFO is older than the TALPA regulations that specifically address and amend landing distances higher for the very same reason they wrote that older SAFO to begin with.

Give it a few seconds real thought Pelmet and see if it dawns on you a little bit.

We do not adhere to anything whatsoever contained in SAFO 15009 because it is old news and not relevant to our operation. If you continue to take issue with that I suggest you contact Transport Canada, the manufacturers and operators and take it up with them. In the meantime, I will continue to do what I am required to do despite your misguided opinion on this topic. As before, I strongly advise all other pilots do the same.

I don't see SAFO 15009 referenced anywhere in either the FAA or TC documentation regarding landing distance calculations since it's been written Pelmet. Other SAFO's like 16009 yes...but not 15009. Why is that do you suppose?

Here is what the FAA states in a current SAFO(19001)...

"The following ACs and Orders were revised or created in support of the TALPA ARC implementation:
1. AC 150/5200-30D, Airport Field Conditions Assessments and Winter operations
Safety
2. AC 150/5200-28F, Notices to Airmen (NOTAMs) for Airport Operators
3. AC 25-31, Takeoff Performance Data for Operations on Contaminated Runways
4. AC 25-32, Landing Performance Data for Time-of-Arrival Landing Performance
Assessments
5. AC 91-79a, Mitigating the Risks of a Runway Overrun Upon landing
6. FAA Order 7930.2R Notices to Airmen (NOTAMs)
7. FAA Order 8900.1 Volume 4 Chapter 3 Section 1 Safety Assurance System: Airplane
Performance Computation Rules, paragraph 4-494 Takeoff From a Runway which is
Wet or Contaminated, and paragraph 4-503 Landing Distances at the Time of Arrival.
8. SAFO 15009 Turbojet Braking Performance on Wet Runways"

Of course, I was correct the whole time and that SAFO 15009 was still valid at the time of our discussion(despite the other poster making an obvious and dangerous assumption that SAFO 15009 must have been cancelled based on its date of issue). However, SAFO 15009 was finally cancelled just this past month, more than two years after the implementation of TALPA and replaced with a new SAFO(19003) that states among other things....

"This SAFO cancels and replaces SAFO 15009 and warns airplane operators and pilots that the advisory data for wet runway landings may not provide a safe stopping margin especially in conditions of Moderate or Heavy Rain."

https://www.faa.gov/other_visit/aviatio ... O19003.pdf

...which is what I have been saying all along. The new SAFO still talks about the 30-40% additive in landing distance required in moderate to heavy rain. This can be accounted for by simply adjusting the TALPA runway condition code on your own(easily done at airlines using an onboard computer) because you may not get the proper condition code from other sources(ie. at the airport where you are landing).

Further info from the FAA from the SAFO.....

"The FAA recommends that airports report “Wet” conditions. However, airports are not required to report when a runway is only wet. Further, an airport may not be able to generate a Field Condition NOTAM (FICON) for sudden rain showers that result in water on the runway more than 1/8 of an inch in depth (contaminated)."

Folks.....Please beware of the information that you get on the internet. Insults do not make someone right. One can see further examples of this by the same poster on the thread about the AC Airbus that nearly landed on a taxiway last year. The same insults and bad information about how it is not proper to use the localizer to assist with aligning with the runway when in fact, the NTSB confirmed that it was a requirement to do so and that the failure not to do so was a primary cause of that incident. Obviously, this poster wasn't doing what was required in the same situation...…...bad info, quite possibly passed on to others flying said airline into SFO.

[Rockie]

To show an example of how a poster can be giving you bad information......


Folks.....Please beware of the information that you get on the internet.

Fully agree. Follow your regulator approved company procedures...not what some guy on the internet says.

[pelmet]

To show an example of how a poster can be giving you bad information......


Folks.....Please beware of the information that you get on the internet.

Fully agree. Follow your regulator approved company procedures...not what some guy on the internet says.

There is validity in this statement but.....blind faith in the regulator approvals is not something that worked out too well for some 737 Max passengers. One needs to go beyond that in a reasonable manner and perhaps get some life-saving info from 'some guy' on the internet.....as I showed was available prior to the second Max crash...…

viewtopic.php?f=118&t=132544

And keep in mind that TALPA was created because the regulator approved company procedures for many years prior was...inadequate. Anyone who believes that there are not other inadequate regulator approved procedures out there is wrong.

[Rockie]

The biggest benefit TALPA provides is standardizing and improving the way airports report runway conditions when it’s not dry.

Since I’ve been in this industry close to 30 years and several airlines before TALPA came along if standing water was suspected the procedure has been to use authorized contaminated runway performance numbers, not some multiplier of wet numbers which are meaningless. If one uses unauthorized, unsanctioned numbers like that when they should have used published contaminated numbers they are literally making up their own procedure and do so at their own, and their passengers, risk.

If any check pilot saw you doing that - trust me - you would fail for intentional noncompliance with procedures and unsatisfactory technical knowledge.

You use dry, wet, or the applicable contaminated....period. Which one to use is up to you based on your best judgement if you wish to be more conservative. The final determination if it’s safe to land is always the PIC’s even if the numbers say you can.

[pelmet]

I wouldn't trust the wet runway performance data. It doesn't come from actual flight tests. It comes from.....calculations based on assumptions agreed to by the regulator. It is a guess and that's it which is why it is called Advisory Data. So if the runway performance is tight but appears to be just within limits, you might just want to re-consider.

Some might remember my original post as shown above. The thread ended up in an 'interesting' discussion which took away from the original post. That I don't trust the wet runway data.

In this report from the NTSB for an Embraer Phenom, it can be seen how wet runway data is created.

https://app.ntsb.gov/pdfgenerator/Repor ... l&IType=LA

"Certification regulations do not require the publication of landing distances on other-than-dry runways, although certification applicants may choose to present this information to the regulator. If the applicant provided this information, it would not necessarily be based on flight tests (largely because of the difficulty of achieving a consistent "wet" or "contaminated" runway surface) but rather derived by calculations based on assumptions agreed to by the regulator."

In fact, wet runway performance data for transport category aircraft is not even a requirement by the FAA or Transport Canada, therefore, if provided, it is considered as Advisory only. But it is requirement by EASA.

"....to certify the airplane in Europe, Embraer proposed to EASA that the unfactored wet runway landing distances presented in the EMB-500 AFM would be computed as 125% of the demonstrated, unfactored dry-landing distance, and EASA accepted this proposal."

In the accident, the pilots came in too fast and with a tailwind. But, there still should have been a deceleration capability as certified by the manufacturer(or provided as advisory info in other countries) and therefore, the aircraft should have been able to decelerate properly, if the crew had operated the aircraft properly(which they did not).After all, a different crew may do everything right based on their performance expectation.

"...Runway 35, even with the higher threshold crossing speed and assuming that the airplane braking performance implied in the AFM landing distances could be achieved, had an available landing distance of 6,016 ft...."

"The findings in this accident and similar accidents investigated by the NTSB confirm that the actual braking coefficient that can be achieved on a wet runway may be significantly lower than the braking coefficient predicted by industry-standard models or the braking coefficient required to match the manufacturer's published unfactored, wet-runway landing distances. The results are also consistent with an Embraer Flight Operations Letter that states that the AFM landing distances corresponding to "standing water" contaminated runways may be more indicative of the airplane performance than the AFM "wet runway" landing distances, even for runways that would not normally be considered flooded (for example, even in the case of "light rain over a non-grooved runway or a concrete polished surface.") In this case, the AFM braking performance was not achieved because the actual braking coefficient generated between the tires and the runway was far less than the braking coefficient implied by the wet runway landing distances published in the AFM."

"Although the runway was not contaminated with standing water at the time of the accident, the performance study revealed that the maximum wheel braking friction coefficient was significantly less than the values derived from the unfactored wet runway landing distances published in the AFM, and was more consistent with the AFM-provided landing distances for runways contaminated with standing water."

In this thread, there has been a lot of discussion about the new TALPA procedure calculation to provide an increased level of safety. However, that does not change the fact that according to the NTSB, that the performance data for this aircraft(and quite possibly a significant amount of other aircraft) cannot be trusted. Which is all I was trying to state from the very beginning.

CRFI or TALPA, the bottom line is that your landing distance on a contaminated runway will likely be flight tested.

This is unfortunately not the case.

[AuxBatOn]

The charts may not be created from flight test data but I would be extremely surprised if a reputable company with an established flight test department doesn’t at the very least spot check the charts. There are techniques available to guarantee an equivalent surface friction to replicate wet/icy conditions.

[2R]

Some aircraft have g load indication , that indicate the g loads on the landing gear .
Smaller aircraft break through the water and avoid hydroplaning by banging it on ? No g loads available .
Any charts for increase g load on landing to avoid hydroplaning and making hard contact ?

[AuxBatOn]

The charts are for a specific landing technique described in the AFM.

[pelmet]

The charts may not be created from flight test data but I would be extremely surprised if a reputable company with an established flight test department doesn’t at the very least spot check the charts.

Maybe....but we don't know which companies have done so. And as we have seen, not every major manufacturer these days can honestly say that they are widely considered to be "reputable".

I took the tine to read through the engineering report in the docket about the originally posted accident. Not the most interesting read in the world for much of it but there are some interesting parts.

Bottom line from how I interpret things....The AFM calculations are based on an assumption about runway friction qualities. Unfortunately, not all runways have the same friction. They wear down over the years and have deposits accumulate. Some of this can be mitigated, such as removing rubber, but it is not so easy for other things such as the runway becoming smoother. And we don't know at least some of this information for most runways we operate on. The performance assumptions are not based on most conservative scenario.

That doesn't mean that newer methods for performance calculations are not sufficient. It just means that there is a good reason why the methods have been revised in the last few years.

"Recent landing overruns on wet runways have raised
questions regarding current wet runway stopping performance requirements and methods.
Analyses indicate that the braking coefficient of friction in each case was significantly lower than
expected for a wet runway (i.e., lower than the level specified in FAA regulations)."

"Over time, the skid-resistance of runway pavement deteriorates due to a number of factors, the
primary ones being mechanical wear and polishing action from aircraft tires rolling or braking on
the pavement and the accumulation of contaminants, chiefly rubber, on the pavement surface. The
effect of these two factors is directly dependent upon the volume and type of aircraft traffic. Other
influences on the rate of deterioration are local weather conditions, the type of pavement ([Hot Mix
Asphalt or Portland Cement Concrete]), the materials used in original construction, any
subsequent surface treatment, and airport maintenance practices."

https://dms.ntsb.gov/pubdms/search/docu ... mkey=90106

[pelmet]

This accident report is quite large but I think it is fairly interesting for the guys interested in performance. It is a good example of how the wet runway performance may not meet the AFM values. In this case because a 'fog spray' had been used over the entire runway to fill in runway cracks.

Which just shows that the wet runway performance numbers may exceed what the AFM says, as I stated in my first post. This could also be affected by rubber deposits from tires, runway polishing from repeated use, etc.

"The friction tests conducted on 9 December 2009 and 15 February 2010 indicated good coefficient of friction, yet the aircraft exceeded the AFM limitations during both tests on the wet runway surface. These two tests by the Boeing crew should be regarded as significant to the investigation, as they highlight two important factors:

(a) The similarity to what was experienced at Bristol aerodrome in the UK on 29 December 2006, when the friction coefficient of the runway was indicated as “good”, yet several aircraft experienced difficulty in braking during the wet runway surface conditions. Even though good friction values were obtained during the post-accident tests at FAGG and making use of the CFME (GripTester) on 9 December 2009 and 15 February 2010 respectively, such tests provided no guarantee that reduced braking would not have been experienced during wet weather operations by landing aircraft at FAGG on a fog-spray-enriched runway surface.

(b) The Boeing crew had the option of utilising thrust reversers, as their CA 12-12a 25 MAY 2010 Page 111 of 188 primary objective was to bring the aircraft to a stop in the shortest possible distance. Even though all deceleration devices on board were activated during these two tests, the aircraft was unable the meet the AFM limitations due to reduced braking effectiveness on the wet runway surface. Should the thrust reversers on the Boeing have been disabled during these two tests, it is believed that the stopping distances would have been considerably longer. The conclusion drawn from the tests was that the runway friction coefficient did not allow the aircraft to perform within AFM limitations and the NOTAM issued by the regulating authority after the ZS-SJW accident thus remained in force."

https://www.baaa-acro.com/sites/default ... ZS-SJW.pdf