Crosswind With Gust Landings
 

:ugh:
For Example;
Runway 36
Wind 270 Dgrs 25 Knts Gust 35 Knts
Crosswind Company Limit 25 Is Knts.
So
What Is Your Intention At The Minumum?
Land Or Go Around?
And Reason?

crosswinds
 

according the the icao document for weather planning, you can ignore gusts. Its at the discretion of the captain.

Given this situation, I would:
1. Query current winds at the outer, middle, and inner marker...if still above company limits, I would go around - depending on my own experience (and judgment call), of course - particularly at that airport.
2. If winds dropped after the go around, I'd try again, otherwise...divert.Would also depend on if other traffic was able to land!
3. Why? If that was truly the company limit for direct cross wind component (seems rather low - I wouldn't think that this would present much of a problem, even in a light single or twin! I've landed in worse during a typhoon! :eek:), better not to have the head office on my back! :ugh:

faire d'income
 

That is why i said at the captains discretion and just highlighted the icao document.

annex 3 if anyone is interested

This is an important operational (technical) subject.
Consideration of gusts in the decision to land, and as a contributor in many runway excursion accidents, is an important airmanship issue. Gusts may ignored for planning, but this should not absolve pilots from considering a forecast of gusts before flight; we cannot hide behind the rules – accidents/incidents can always find errors of judgment.
When deciding to land in a crosswind with a steady component at or near the demonstrated limit, a pilot is unlikely to have knowledge of what magnitude / duration of gust it would take to exceed the absolute limit – the ability to retain control of the aircraft.
Note the errors in reporting wind speed in the link below. Also, think about wet runways.

“Crosswind Certification - How does it affect you?”

Safety aspects of aircraft performance on wet and contaminated runways.

“How Good Pilots Make Bad Decisions.”

EDIT new link for How Good Pilots Make Bad Decisions, via Google

http://uk.geocities.com/[email protected]_ISAP_162.pdf

Which ICAO document?

sleepybuddha
 

I just have the page photocopied the page but its Annex 3

Title is 'Application of aerodrome forecasts (TAF and trend) to pre-flight planning'.

I have tried to download the annex from the web but you need to pay for it. i would suggest you/or your ops department get you the document. I am not based at mine so cannot give you any further page numbers etc at the moment.

Don’t really see why this ICAO document is relevant.

Your airline SOP's take precedence anyway, if it isn’t clearly stated in their manuals then id ask for clarification from the chief pilot.

At my airline we are told to ignore the gusts (for x-wind limitation purposes) however if your over the threshold and struggling to get the thing on the black stuff just go-around, and the decision to do so can be made by either pilot

I say again from the origonal post....
 

AT THE CAPTAINS DISCRETION.

Compare your SOP's to some legal documents etc. and you will find a unusually strange reflection. SOP's are legal then commercial.

For example take a look at 'destination alternates' in your SOP manual then consult EU OPS. There may be a comma out of place but thats just translation. No need to speak to the CP about it.

Flyngtincans: To ignore the gusts. Where does that come from. Is it personal advice from the chief pilot, or discretion of the captain (as i have said on every post), or a limitation written down.

May I ask: have you read annex 3. And what are the wethaer planning minimums adopted where you fly. Can you reference that document.

Whay do you think the chicago convention is not relevant.

Anyway to answer the original question,

I would go-around, hold to wait for an improvment if you can, if not divert.

Why? Because your right on limits and have gusty conditions, the aircraft limits have been demonstrated by a test pilot and im not a test pilot.:ok:

Amazing how SOPs vary. Ours are very specific (and nanny like) in that we MUST factor in gusts.

Flyingtincans
 

That was your original post.

That was your second. How did I prove your point as you did not make the same points.

If your SOP's have everything clearly stated then you must have a vast library on the aircraft. For example, do you or the aircraft have a copy of EU OPS etc. (or equivalent)on board. Or is it somewhere to reference.

Surely, planning takes place throughout the flight.

If your not worried about the original documentation why did you read annex 3.

I keep stating 'at the captains discretion' and on my last post I put it at the top in upper case. I can't be any clearer.


Taking the commercial air transport aspect out. Remember crosswind limits in your POH are generally 'max demonstrated'.

Jamestkirk you have taken this thread far from the original question. My point was your SOP's etc are approved by the CAA, whom have drawn up the national reg's from the ICAO documentation, as the books get re-written down the food chain they are either copied or even further restricted.

So your SOP's do take precedence because they will be at worst the most restricting and at best the same! Are you suggesting that you should ignore company SOP's because ICAO say something different??!

Of course it does, but from a legal perspective, planning takes place on the ground before you are airborne, once your wheels are off the ground a different set of rules come into effect.

For example you cannot plan to launch for an airfield that wont be within your planning minimum for your ETA +/- 1hr. However if while you are on the way it is out of limits you can continue all the way to the final approach point before you divert, OR if your past the final approach point and the wx then goes out of limits you can continue to actual minimums.

Because you need to read it for the ATPL groundschool

The captain doesnt really have much discretion to excersice in this case, minimums are minimums and limits are limts, he could decided to bust one of them but he needs a damn good reason to do so i.e saftey

minimums
 

When did I say the captain will bust minimums. Please look back at the post and find where I said that as I cannot find it.

We are talking about gusty conditions outside of the aircrafts limits and my original post clearly stated that you can, if you wish, for whatever reason, disregard the gust factor for planning purposes as per the ICAO document.

I did not state anywhere that when you get to your DA/MDA, the captain can choose to ignore them and carry on.

But you are right, it is going a bit off piste.

To answer the question (# 1):-

• Crosswind Company Limit 25 Is Knts.
  Excellent company policy, few operators add specific clarification to manufacturer’s documentation.
  A play on words, but 25kts is a Limit thus anything above that is ‘prohibited’.
  The comparison here is with CS 25 certification regulations. Maximum demonstrated crosswind is what has been shown to be safe, beyond that aircraft handling is unknown; “the demonstrated crosswind value may be presented in a section (of the AFM) other than the Limitations Section.”
  However, “If the maximum demonstrated crosswind is considered to be limiting for either take-offor landing, the crosswind limitation must be stated in the Limitations Section. If the crosswindvalue is considered to be limiting for one type of operation (e.g. autoland) but not for another,the crosswind limitation may also state the specific operations to which it applies.” AMC 1581.
  
  
• What Is Your Intention At The Minimum?
  Go Around. But why wait until the ‘minimum’, go-around early and don’t get sucked in by the actions or opinions of other pilots or risk you own false assessment / change on mind (human factors – plan continuation bias).
  
  
• And Reason?
  As above, the text provides a limit without exception. If the operational management wish to provide guidance on gusts then additional information must be provided, with I hope sufficient justification.
  Don’t forget that individual pilots ‘own’ the SOPs just a much as the management do – SOPs should be a communication device providing guidance, knowledge, and justification. There are not ‘the law’ as they cannot accommodate for every situation.
  Additional reasons, variability of steady wind and gust, accuracy in measuring and reporting winds, and need to judge runway condition; not all ‘dry’ runways are dry.

For info, from the regs:
CS AMC 25.1327. re HUD para14.1.4.1 “Approach mode guidance, if provided, should be satisfactory throughout the intended range of conditions, including at the minimum approach speed and maximum crosswind, with expected gust components, for which approval is sought.”

So HUD operators may have a crosswind limit which specifies gusts, perhaps smilarly for some auto land operations.

Go around. :ok:

(It says in our manual that gusts shall be included, but may be ignored at the captains discretion when it is considered it will absolutely be of no operational signifigance, which I've yet to seen applied.)

Edit: the above is NOT the wording in the SOP, sorry for the confusion on my part. The wording is "when adhering to the wind limitations the Commander shall include gusts that might be present during operations but he may exclude reported or forecast gusts that definitely will not be a factor for a specific operation".

bfisk, an interesting choice of words for a SOP. You may wish to ask your management for their explanation of ‘absolute’.
Again, a ‘play on words’, but very few things are ‘absolute’, thus in gusty conditions you cannot be sure that something remains which is operationally significant.
Yet again, what is significant? This implies a balance of risk, which requires knowledge of the risks in the operation. This is interesting because researches inform us that the misjudgment of risk is a significant contributor to error in landing accidents.
IMHO, the SOP invites opportunities for error, particularly where ill disciplined thought, or ‘subconscious’ human factors pressures might sway the decision; the "but may be" allows an errant way out.

Another reason for discontinuing an approach in gusts is related to skill and currency.
The certification regulations define limiting crosswind conditions as not requiring exceptional pilot skill, which is similar to most aspects of manual flight.
Manual landings are flown in a range of conditions and the basic skills checked regularly, but the skill in crosswind landing may not be practiced or checked at all.
I recall that flying a crosswind landing in a sufficiently strong wind was a required in the initial license flight test – it took me a month to wait for the wind. Thereafter I don’t recall any such test or check; I could have flown the reminder of my career without encountering a max crosswind.
Where pilots are not familiar with strong crosswind, what risk do they consider about their current ability (currency) to fly a demanding landing; as research shows, pilots overestimate their own ability to deal with a perceived risk and to fly the aircraft in difficult circumstances.

Ref: Risk perception and risk management in aviation.

One of the defensive measures discussed in this article is to focus on why ‘should’ the activity be undertaken, and not how ‘could’ it be done. We have to explain the reasons for our decision, first to ourselves, and then to others.

Here's what my company ops manual says!

But it also says:

Mungo Man, another interestingly worded SOP.
Perhaps the following is a pedantic review, but confusion often comes from ill structured SOPs when under high workload and in time pressured situations.
The text encourages the assumption that all wind reports are mean winds; a reasonable view, but perhaps it does not consider errors in reporting wind *.
Is the mean calculated (computation) or just an eye-ball figure by the observer? In some circumstances the mean wind may have included gusts (the max and min) of a varying wind *.
The commander is allowed to use judgement in gusts, but what is assumed about the ability to judge, what are the risks, how might these be countered.
IMHO, the management have relinquished their responsibility and passed it to the commander – unfair, the commander is someone who they should be protecting - his safety is their safety. Everyone has a safety responsibility which should not be given up.

My interpretation of the text describing the max demonstrated crosswind associates the gusts with an airspeed increment for the approach, but some people might associate this with a crosswind gust – already stated in the previous text.
Whilst airspeed increments in gusting conditions reduce the risk of low energy situations during the approach, crosswind gusts require increased control activity, perhaps encountering a limiting situation close to the ground or even on the runway – more rudder required as speed reduces (until wheel side force helps the situation).
In strong gusting crosswinds, a prudent commander might reduce the crosswind limit by half of the gust increment.
Who in the airline has made the ‘considered’ judgement that the max value is not limiting, how did they determine this – fact or supposition? If this is the manufacturers wording (certification speak), then who can discount that the real ‘limit’ might be a few knots higher?
And where is the advice for operating on a wet runway?

Guidence of the wise and adherence to for fools.
 

Cross winds:

This quote! PEi 3721:
Maximum demonstrated crosswind is what has been shown to be safe, beyond that aircraft handling is unknown.

This is incorrect from my understanding of the certification requirements.

If the Aircraft is placarded with the words "Max Demonstarted Cross Wind 25Kts:

On the day of crosswind certification demonstration, the Captain/crew/pilots/test pilots/monkeys/ whatever! on this day may well have been Demonstrating in 25, & maybe 35 kts, maybe even 30 gusting 40,whatever! they being the demonstrating Crew/Captain for this exercise may enter in the little box Eg 25Kts, as the Captain/test pilot will recommend this as a good average for the average pilot:

In the comments section he may write, and you could quite reasonably expect to see something written like: (wind 30-40kts, no handling surprises, good predictable directional control with rudder in these conditions a safe average of 25kts is acceptable)

IT DOES NOT MEAN: QUOTE! "Maximum demonstrated crosswind is what has been shown to be safe, beyond that aircraft handling is unknown":suspect:

****e: 26kts and my wings fall off.:ugh:

Many a time with a company SOP limiting at max demonstrated, yet routinely operating into scheduled destinations in "scheduled seasonal" windy conditions, the wind would be a steady 30-35kts, at a particular time of the year for a month or two, no one ever diverts, nor cancels flights! does this mean we are operating unsafe! NO, if on the other hand, it becomes more than just wind with the odd "gentle" gust, ( low vis, drifting sand, gusts of 30-40kts) on top of the wind, then as has happened to most of the other pilots and myself, power up and get the hell outa Dodge.

If the aircraft is placarded with MAX CROSSWIND OPERATING LIMIT 25Kts, This is an aerodynamic/performance limitation and it needs to be more closely, "stringently adhered to".

Rules, what do we do with them? "the generation of the now" have no idea on how to use professional discretion.

I believe the wind passed by ATC when cleared to land is the average (with gust bearing in mind the definition of a gust is 10 kt or more from the mean wind speed) over the last two minutes.

You can of course ask ATC for the "instant" wind.

Flying at crosswinds near or at the demonstrated value is not without risk. Most pilots will not do this on a weekly basis and training simulators are not very good in representing the effects of gusty winds on the airframe. Furthermore the way the certification works makes you wonder how realistic demonstrated values are to the airline pilot. I have studied this topic for many years now and analysed numerous accident/incidents related to crosswind. The gustiness of the wind played a very important role in the vast majority of these cases. There has been little progress in solving some of the important issues.

Some recommended reading material:


Crosswind Certification - How does it affect you?


http://www.nlr.nl/id~5114/lang~en.pdf

and

Safety aspects of aircraft operations in crosswind

http://www.nlr-atsi.com/downloads/NLR-TP-2001-217.pdf

hoggsnortrupert, I’m not sure where I am on your scale of assessors; probably in all categories, and particularly after a poorly judged crosswind landing one might as well be a monkey.

Whilst the certification requirements may not be precise, they do, with additional flight test guidance, provide a basis for determining crosswind conditions suitable for an ‘average’ pilot – on an average day, etc, etc, - all things being equal – except they rarely are.

The manufacturer’s tests involve ‘considered’ opinion; however, in my experience not by an individual but as a team effort. Both crewmembers have probably flown the test, and in alternate directions for a given crosswind. After which the air and ground-station data is reviewed, then discussion with AeroD, airworthiness, training, and occasionally the certification authority.

The manufacturer may have flown landings in conditions beyond ‘the max demonstrated’, but in circumstances where the conditions were unstable or data unavailable. This experience is often used when considering the results of actual tests – either a lenient or a more restrictive judgment. However, what might be known to a test crew is unlikely to be available to a line pilot, thus operation beyond max demonstrated is best treated as ‘handling unknown’.

Crosswind certification is one (if not the only) area where there is no margin at the limiting condition; compare with Vmo-Vne, Vref-Vs, or runway length required. Most flight operations provide the crew with considerable protection from the randomness of the environment and occasionally their own judgment; crosswinds can be very unforgiving.

Pilots who land in cross winds/gusts greater the max demonstrated, in the circumstances which you describe, are not necessarily ‘unsafe’ – that’s a relative term, but they are, perhaps unknowingly, accepting high risks.
Often high risk operations are successful, and this is used to redatum a pilot’s norm – a biased, habitual behavior.
We rarely understand all of the risks taken in an operation or the effects of ‘so called’ risk alleviating procedures; it might only require a small change in the conditions to invalidate what a pilot has assumed from previous inappropriate use.

You correctly respect a hard ‘limit’, but interpret max demonstrated as something with margin; I disagree.
As explained above and in previous posts the as-yet-undetermined ‘hard limit’ may only be at max demonstrated +1kt; thus any landing above max demonstrated might have unacceptable risk with severe consequences.

Rules, what do we do with them? "the generation of the now" have no idea on how to use professional discretion.
Rules don’t prevent crews from exercising discretion; they enable discretion, which can be exercised on the safe side of the rule (limit), without bias, and being fully aware of the assumptions being made.
Whilst I would agree that many pilots, both old and new, fail to comprehend this, it is not necessary to encourage pilots to take risks to exercise their discretion.
Discretion (prudence, judgment, carefulness, caution, responsibility) is not intended to identify risk taking opportunities; it is to minimize risk, thus maximizing safety.

Refs:
CS 25 Certification of Large Aircraft (FAR similar).

AC 25-7A Flight test guide for certification of transport category airplanes.

Some good technical / professional content in this thread; NLR links well worth reading.
Suggest that Mods move it to Tech Log for wider viewing and response.

Well said PEI3721. Discretion to step outside SOPs / "limits" is something that is exercised and understood by more modern pilots than the previous poster suggests. Whilst the quantity of printed procedures we have is greater than that of 20/30 years ago, they have been included to avoid repeats of other pilot's misfortune.

More rules don't necessarily make more robots. It's unfair to suggest the rule-conscious pilot has no initiative.

Old thread resurrection
 

Hi there
I’ve been handed a topic about crosswinds from my (ATC) boss and noticed this thread.
Here’s an excerpt from CAP789 (UK) - Requirements and Guidance Material for Operators...I think it’s current?...

Crosswind Limits for Take-off and Landing

It is not sufficient to repeat a statement in an AFM that
a particular crosswind component has been found to be acceptable; operators' limitations should be stated in unequivocal terms and account taken of the effect of gusts and surface conditions. Limits in excess of any figure mentioned in the AFM will not be acceptable. In addition, consideration should be given to any reduction in limits due to narrow runways.

So what do your SOPs state with regard to (a) max crosswind component for dry runway, (b) max crosswind for wet, or worse, runway, and (c) what about gusts for either dry or wet, or worse, runway????

Is there a percentage degredation for wet runways? I’ve heard of +15% for landing distance (unless runway is advised of “slippery when wet” - in which case landing distance is further increased) but what about gusts? Anyone have a rule of thumb for dry and wet runways???

Also, does a 15% increase in landing distance equate to a 15% reduction in crosswind limit???

Is the same true for “narrow” runways?

Over to you.....

And, while I’m at it, does damp make any difference?

Damp is not dry, so it is wet, unless you have specific charts for damp.

Does a grooved runway make a difference?

Gusts do not apply during planning. But they do have to be taken into account for landing (and takeoff). given the additional company restriction I’d ask for instaneous winds. If these were beyond the company limit just before landing (not necessarily at MDA/DH) even if fully stabilised I’d go around. If instaneous winds were not available I’d divert. This is obviously the company’s intention and it’s what you are paid to do and must have been budgeted into their operating costs. That the aircraft is still within its crosswind limits and other operators of the same type are landing is irrelevant.

Thanks TAd

A lot of this depends what is explicitly written in your OM A. My current company has a blanket statement that damp runways are wet for performance purposes. My previous company had bespoke options for certain performance limiting grooved runways.

Regarding crosswind limits, my previous company had fixed limits written into the performance manual, with a written calculation method to factor in gusts. My current employer defers to the manufacturer guidelines in the Flight Crew Training Manual which gives the Captain a measure of discretion regarding gusts.

The crosswind limits decrease based on the braking action on the runway, but the landing distance available doesn’t come into it.

good egg, first to reiterate some previous points. Crosswind ‘max demonstrated’ is in the Operating Manual as advisory information. The AFM contains limiting conditions as hard aircraft limits (rarely for manual landing, always for autoland).

Previously, aircraft manufacturers published advise according to what had been tested for manual landing, usually on an opportunity basis. This might only relate to dry runway, or steady wind. However with increasing focus on runway excursions, manufacturers might now provide expanded advice on interpreting gusts, wet or contaminated runways, width, etc.
The message is to read the small print in the manufacturers documents.

There are several safety publications with advise on wet crosswind restrictions, but the manufacturer should always be considered first. Then assess other factors as per landing distance, how wet is ‘wet’, what form of contamination, type of runway surface, width; all relate to crosswinds.
Wet smooth concrete may be like like ice. High-friction porous surfaces are generally good, providing that they are not contaminated with rubber or dust . Grooving should not be included in assessments unless you are sure that the grooves are clear and provide good drainage, which may not the case after a heavy downpour.

IMHO advice given re crosswind component should be treated as a limit, and further restriction applied for gusts, particularly as the actual variation is unknown; ATC reports are not absolute, wind not measured at the threshold, only an average, etc.
If you don’t know, not sure - how wet, what gust, width; give yourself more margin.

TA, #33, does the U.K. CAA agree with that view? IIRC there was a policy statement that there is no such thing as ‘damp grooved equals dry’?

Jw, #35, re landing distance; except when using credit for reverse to stop, and reverse affects directional control - fin blanking etc, or an aircraft type tends to lift a wing in crosswinds without sufficient aileron input.

Thanks all. Useful info.