PPRuNe Forums - How much value do you give Braking Action reports?

PPRuNe Forums (https://www.pprune.org/)

- Tech Log (https://www.pprune.org/tech-log-15/)

- - How much value do you give Braking Action reports? (https://www.pprune.org/tech-log/617138-how-much-value-do-you-give-braking-action-reports.html)

How much value do you give Braking Action reports?

Braking Action PIREPS are subjective. With autobrakes and antiskid systems participating in (and possibly masking) part of the effort to stop, how much value do you give to a previous arrival's braking action report? Are you able to determine the difference between Good and Medium, or Medium and Poor subsequent to your own landings?

Always downgrade a little conservatively, except when reporting GOOD.
So MEDIUM-GOOD becomes MEDIUM for safety reasons, etc...
Too many times I've landed on a reported 1mm covered runway without seeing any lines under the snow layer and traversing over the ridges of snow rolling out, while reported to be MEDIUM-GOOD.
Wonder sometimes why airports give us pilots trying to land readings or measurements which are inaccurate to say the least, based on a runway inspection some time before landing during snowfall without intermediate clearing operations.

Autobrakes and antiskid are actually valuable indicators in making reports. You should be able to feel the brake releases when antiskid is working. If the antiskid doesn't have to do anything, I call the braking action Good. If I can feel a moderate amount of action, I'll report Medium. If the antiskid is working very hard, and/or there is significant yaw induced because of asymmetrical brake releases, I'll report Poor.

This is one good reason why it's far nicer to stop first, then land.... ;)

None, #1, ‘none’.

Airbus provides a balanced view in their Safety First magazine - ‘Using Aircraft as a Sensor on Contaminated Runways’.
I heed their view “Making an accurate braking report can be difficult for a pilot because it relies on their subjective experience of the landing”, thus PIREPS are of little or no value in making ‘your’ decision to land.

From a Pprune sage “I don’t bet my butt on the feeling in someone else’s butt”, i.e reports are subjective and others have no idea of the reporters experience in the conditions, nor the aircraft or retarding systems selections or characteristics.

It’s very difficult to ignore a report once it has been broadcast. The advice post TALPA is not to give a PIREP unless it downgrades the existing braking action.

https://safetyfirst.airbus.com/using...nated-runways/
download PDF, or via
https://safetyfirst.airbus.com/app/t...df.php?p=13846

Intruder,
your personal subjective scale is exactly the reason why PIREPS should be ignored; there is no standard, measure, yardstick, for pilot sensed braking action.

Quote:

Originally Posted by Intruder (Post 10358189)

Reporting a poor breaking action is no joke . There are plenty of operators that will not allow landing if braking action is reported poor.

I just don't see how pilots would be able to judge breakin action. This is a value that lives depend on. Shouldn't just be left to opinion. Too many factors at play .

Interesting article from a while ago here. It's basically the same concept as the one safetypee is describing. PIREPS on braking actions can be valuable in a very limited amount of conditions.

I read somewhere, that airbus or boeing are writing software that monitors deceleration and breaking effort and transmitting it live for real time braking actions. Will be a huge improvement from basically a car doing 50mph on runway, to a 60 ton jet doing 150mph...

RAAS (runway awareness advisory system) is already available and operational in some airlines...

RAAS, #10, is a very restricted aid. It is only ‘advisory’ and lacks the ability to alert (or not) in context; see discussion on 777 Dubai accident.

An Airbus alternative is ROPS, which has both predictive alerting - advice in the air, and reactive - ‘commands’ on the ground. Both aspects still depend on the accuracy of the pre-landing data input. The computation has ability to deduce’ the braking action based on reported contaminant type, depth, and extent of coverage, or by crew inputs, i.e. subject to ‘PIREP error’. As with many modern thinking machines, their value depends on input / sensors.

Advantages of ROPS are with combined audio-visual alerts before touchdown, and ability to give a course of action when in the runway. The options for action might be no better than a pilot might have, but the need for change it is sensed (measured) by the aircraft, not the butt, and thus the crew is quickly alerted use all of the remaining safety margin. Some viewpoints support the idea that humans will react to a machine alert quicker that an individual’s decision depending on experience and frailties of ‘biased’ judgement.

ROPS page 21 - http://aerosociety.com/Assets/Docs/E...%20Chapman.pdf
also
page 47- https://www.icao.int/SAM/Documents/2...nting%20RE.pdf

I would not ignore braking reports by other pilots flying the same model aircraft I am flying. I would use those reports in combination with other sources to attempt to put together a complete picture of braking action on the landing runway. Official reports can be old or, in rapidly changing conditions, invalid. A PIREP from an aircraft which landed immediately in front of me would carrry more weight than a 30 minute old RWYCC. Turbulence reports are also subjective, we don’t ignore those but also put them in the mix in an attempt to create a complete picture.

Salute Mongo
You have same thots as I, and I cut my teeth on anti-skid lites as a youth flying up in the frozen north across the U.S./Canada border.
Of course, over the years the anti-skid systems got better and we no longer experienced the "complete" release of the brakes at beginning of a skid, but rather a more gentle release of pressure as we experienced carbon-based critters would do. My last jet could allow a hamburger like me to press hard on the brakes and Hal took care of braking pressure.
Getting a PIREP from your wingman/flight lead who landed a minute in front of you is what I would go with 95% of the time, especially if we had discussed braking technique due to the weather forecast and past experience.

Quote:

Originally Posted by Airmann (Post 10358793)

I have just described ONE way to judge breaking action. Along with that is the actual distance needed to stop. Maybe those operators would be thankful that someone warned them ahead of time, and they had enough fuel to go to their alternate...

Braking action reports are as arbitrary as ‘ride reports’ or turbulence reports.
They are in indication and not the holy word brought down the mountain by Mozes.

My airline has been running a trial called CORSAIR (COntaminated Runway State Automatic Identification and Reporting) on the A320. From what I've read it works like this, it monitors objective braking action during landing electronically and then uploads its braking action report to a central unit. This objective information can be then sent back (automatically) to the tower at the relevant airport to generate an honest BA report. This essentially dispenses with the subjectivity that a 'Braking Action' PIREP might elicit.

I'd rather not post company material, but found this online: https://ral.ucar.edu/sites/default/f...4-kicinger.pdf

Some airports don't measure, or don't report Braking Action. For instance, Narita.
I once taxied out there in a tropical storm - torrential rain was falling and it was blowing a gale. 25kt mean crosswind. The ramps and taxiways were flooded.

I asked ATC for a Braking Action Report and was told 'Not measured or available'.

So what do you do?

Assume the BA is 'Good' and just plough on?
Or assume it's Medium and in fact outside limits - then what?
Or assume its really what it looks like - Poor - and taxi back in?

I'd take a PIREP. In the circumstances its your only option.

This has been such a pain for so many years. Braking action, braking coefficient, medium or medium good...and so on.
Contaminants of different types and depths across a specific percentage of the specific runway length...phew....what an equation.
IMHO TALPA has done a good job with the RCAM and the RWYCC's in an effort to unify procedures and above all KEEP IT SIMPLE.
It's not a perfect system but, it gives a good picture to the flt crew and then takes into account the PIREP....Braking action only derives from the crew that handles the aircraft.
In 2019 3 Scandinavian airlines, operating Airbuses will have the Braking Action Computation Function (BACF), Results will go through ACARS into NAVBLUE and everyone will be happy

gig, #16, thanks for sharing.
This system, like those previous referenced, still depend on the first aircraft having a sufficiently accurate description of runway conditions in order to establish a baseline from a ‘successful’ landing (i.e. it might not necessarily have been safe). Subsequent aircraft will benefit from the information gathered and thus the overall operational safety should improve.

An overview of other initiatives in this area, including COSAIR as a complementary function.
https://www.ecologique-solidaire.gou.../CPS_RWYCC.pdf

Are opinions such as those in #17 representative of current safety attitudes; do they stem from training or social influence? An alternative is that as an open forum we have to entertain those who seek personal gain, spotters, gamers, spammers, etc; but in a professional forum the slightest ill-informed post might influence beliefs and understanding for the unwary, or perhaps any of us subconsciously.

In the absence of reported conditions flight operations depend on judgement; wind and heavy rain should indicate the need for additional caution.
Assumptions should not be the basis of any decision; assumption has value in self-assuming that your assessment, judgement, decision, could be flawed, thus some additional safety margin is required.
If you are unable to form a sufficiently accurate assessment of the runway state; ‘if you don’t know then don’t go’. (A sufficiently accurate assessment - before the event, is something which you can defend after the event.)

Using PIREPS is an assumption; that those people have a better understanding than you, but what is the basis of their judgement. Safety related decisions should not be delegated either by assumption or using reports of unknown quality without compelling evidence and consideration.

An objective of operating safely is to always have options; then using professional skills manage them. If you believe that you have no option, then you have overlooked something, think again and particularly consider the option that you should not to fly at all.

Quote:

Assumptions should not be the basis of any decision

Self evidently.

Quote:

If you are unable to form a sufficiently accurate assessment of the runway state; ‘if you don’t know then don’t go’.

In the ideal world, yes.
The real world is rarely ideal.

Quote:

Using PIREPS is an assumption; that those people have a better understanding than you, but what is the basis of their judgement.

A pilot who has just landed on a waterlogged runway has a better understanding of the runway condition than a pilot waiting to take-off.

Quote:

Safety related decisions should not be delegated either by assumption or using reports of unknown quality without compelling evidence and consideration.

In the example I mentioned, I approached the holding point of the TO runway with a crosswind that was either just within, or significantly outside of the crosswind limit, depending on braking action (which was not available from ATC).

As I waited I watched a BA B787 in the latter stage of his approach. In the extremely gusty and turbulent conditions I could see him struggling to control the aircraft - and he did a damn fine job, putting it down in the TDZ and braking to clear the runway.
When he was clear I asked him for a PIREP. He replied 'Medium' and that put our take-off out of limits.
There are some airlines I might hesitate to put credence in for PIREPS, but BA is not in the habit of putting aircraft off the end of runways, so I definitely heeded that PIREP. And of course it confirmed what I suspected - less than good braking action, and a no-go.

Conditions can change quickly in tropical storms, bands of rain sweep through bringing worse weather, and then they pass, giving temporary lulls. In addition the eye of the storm is moving, so the bigger weather pattern is affecting wind direction over time. I anticipated the crosswind would begin to reduce after a while. So we waited. We did not 'give up' and decide to 'not go' because the company I worked for (an Asian airline) would not support any such decision. They would expect me to provide EVIDENCE that the braking action was not GOOD. Giving my 'opinion' would not cut it.
This is where your 'ideal world solution' clashes with the real world for many pilots.

By the way as we sat and waited for things to change (about 45 minutes - I took the extra fuel expecting this to happen) we saw around 10 aircraft take off. Including same type aircraft. Pretty tough to sit there and wait it out while everyone else is just blasting off. But in the absence of airport measured braking action reports they may well have all felt entitled to do so!
Would you have been one of them? Because the consequence of your choice to ignore PIREPs is to put ALL your decision making on your own judgement - which (as you point out) could be very wrong. And if your answer is always 'then don't go' I don't think you'd have a job for long in these here parts.

The wind subsequently backed onto the runway sufficiently for us to depart in a lull.
I still feel I did the right thing by my passengers and crew in obtaining that PIREP, and delaying the take-off.