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alexban
19th Mar 2004, 18:09
Hy
I wonder what is the crosswind limit for autoland on 737.The OM specifies 20 kt crosswind for dual chanel if CAT 2 or 3 app executed.What if the weather is CAVOK? (with a crosswind of 30 kts)
What are the limits for autoland on Airbus (320 family)?

Brgds Alex

wing737
21st Mar 2004, 08:03
So you are a 737 pilot(as seen on your profile)and asking the crosswind limits of autoland on a internet forum?I am surprised.What type of 737 are you flying anyway?

alexban
21st Mar 2004, 16:34
wing737 : As I see from your profile you are pretty new here,so I can wait for you to grow up :)
My friend ,first this is not just a "internet forum" ! If you think so,better go check the CNN ,or AOL or some other site. This is a site for professionals or aviation fans.You can find here some of the best,and you can learn a lot from them.
Second,how"many types of 737" do you REALLY know? It's easy to be just a smart a:mad: than answer a question .
Just to answer your curiosity I am type rated on 737 3/4/5/6/7/8 and at present time I fly the 3/5/7 series.(several thsd hrs on type :ok:)
And back to my question, what is your policy (limits) regarding max crosswind autoland?
Brgds
Alex

seat 0A
22nd Mar 2004, 07:29
Well, Alex, I have to admit that I understand the scepsis of mr. wing.
If you are really a 737 pilot, and cross rated on the different types (like myself), you would realise that the different types all have different crosswind restrictions for autoland.
You would also realise that the autopilots don`t give a toss what the weather looks like, outside :D

p.s. knowing the crosswind capabilities of the 737 autoland, I wouldn`t try it with 30 kts crosswind. Especially on the 3/400 it is not a good idea.

mcdhu
22nd Mar 2004, 07:58
Alex,

A320/321 Cat 3 Auto app and ldg:

Hd: 30kts
Tail: 10kts
X: 20kts (RVR less than 100m: 10kts)

Cheers,
mcdhu

alexban
22nd Mar 2004, 18:04
Seat OA: I agree with you about the weather. I'm a bit puzzled because,as I said ,tne OM says 20 kt crosswind for dual chanel if CAT 2 or 3 app executed.
Why was this phrase required? I know the cat ! ils won't give the protective area as a cat 2or 3,thus maybe some restrictions on performing autoland on cat 1?
Are you doing autolands on cat 1 app?
I did few autolands,maybe less than a dozen per year,all on cat 2 conditions.
I also agree with you about the 400,also the 800 series.But what about the 3/7 series. You'll be surprised,but I know of autolands made at 40 kt's xwind,perfectly done by the plane.(700).There were ,of course,on test flights.
And you didn't answer my question.Some numbers would've been ok.
Thks
Alex

seat 0A
22nd Mar 2004, 18:28
fair enough,

We do autolands on cat1 approaches.
We have the following numbers in the OM:
-300: head 22, cross 17, tail 10
-400: head 35, cross 20, tail 10
-800/900: head 25, cross 20, tail 10

We don`t do autolands often, in fact I made about 6 autolands last year.
There`s no difference in crosswind-limits for various weather conditions.

Regards

80/20
23rd Mar 2004, 06:31
Does alexban’s question show poor knowledge?
I do not think so because he is simply asking how various operators follow manufacturers guidelines which is encouraging individual operators to develop their own limits.

The regulators do not require manuals to include autoland crosswind limitations.

In general, Boeing’s crosswind information contains guidelines not limits. Complete limitations are not even included in the AFM. Crosswind guidelines are provided to assist operators in establishing their own crosswind policies and that’s what alexban is asking for.

Some Boeing AFMs have crosswind autopilot limit for CAT II & III autoland. This is not part of the manuals normally given to line pilots or stored onboard. Many operator’s SOPs have the same limit for autoland as they do for CAT II & III typically such as seat 0A has given above.

wing737
26th Mar 2004, 15:02
Alexiban,

Cool down my friend.I might be new in this forum as a poster but I an a long time visitor around these forums.I've seen lots of enthusiasts who wants to learn from pro's(which I respect).
If you really are a professional you should know that these forums are not the place to sharpen your technical knowledge.(Even if the 737 chief test pilot himself is a contrubutor)
As a pilot if I need any kind of information I speak up about it with my experienced captains (only with the knowledgeble ones and the ones willing to share it)during long cruise hours instead of just drinking cofee .We both check it with our books,company documents, support with experiences.After I go home I cross check it from my sources again before adding it to my brain.
There is no dangerous pilot than anyone who accepts every crap heard as a solid fact just because someone in a forum said so.This person might be the most experienced pilot or an weirdo pretending to be pilot.

Human brain "forgets" critical details when not updated regularly but your books never.So you should learn what ever you need from your company documents,ask help from your instructors and captains.And use these forums as a reference where to find the info,not as a ground school even though you refer the contrubutors as the best pilots my huge pilot ego can not accept anybody around (whom I can't see)to be better than me(no offence to anyone)

To answer your question which 737 I really know,I am flying 7374/800's at the moment.We use
Headwind:25kts
Tailwind:10 kts
Crosswind:20 kts as wind speed limits, for Auto lands.
For training purposes we perform auto lands in good weather also(CAT I limits).

Do you think you can have more than 20 kts of wind in CATIII conditions?

Right Way Up
26th Mar 2004, 16:25
Wing737
Simple answer - Yes!

alexban
26th Mar 2004, 21:05
Wing737 :
What do you think of a sand storm? Not a nice place to be in ,landing at CAt 2-3 on a very windy day :)
I never take anything for granted,nor here,nor spoken by any "experienced captains' I've met. But all the thinks that I've learned here or somewhere else I used to improve my knowleadge about the plane or aviation alike.I have all the books ,and one,I can say, big database about the 737,and I crosscheck all that I learn here ore there about it.
I've met experienced pilots who doesn't like vnav,lvl chg,speedbrakes,who recommend autobrakes,or not ,which told me a lot of good thinks ,and also some crap along the way.All of them are top pilots,I can tell you this,but nobody knows all there is.
So,my point is:take information,questions,answers,from everywhere you can.Than check your books,maybe the net,or boeing site,or jaa,whatever,and keep what's good for you.
You can hear of a lot of things that didn't cross your mind untill now.
You should've answered like this from the first time.I like to think that we are all friends here,maybe one day I'll be happy to have the chance to drink a Fosters with you at a bar in Istanbul.:O
:ok:
Alex

None
26th Mar 2004, 21:59
http://www.pprune.org/forums/showthread.php?threadid=109287&highlight=Autoland

wing737
27th Mar 2004, 10:35
Alexban,
During the last 4 years I flew for some African Airline companies as my company wet leases the planes during the low season.I've spent a lot of time around Sahara desert and central Africa and during this time I've seen a lot of sand storms(try to walk around the airplane during blowing sand and youll be surprised when you find sand even in your underwear in the evening)

I can agree with you with the low visibilty that the blowing sand brings associated with high winds but a CAT III in those airports,hardly I must say.Most of the airports around the desert doesn't even have ILS installed(been to places where you are the one of 4 airplanes landing daily)Mostly in sand storm conditions if its forcasted we delayed,if not -more than one occasions- we had to divert to another place because visibilty is over the limits.

Another interesting point to consider about CAT III in sand storm is different from fog conditions, the direction of the wind must be associated with runway which is CAT III capable,I have never seen any airport in desert with all runways CAT III capable.As I said hardly equpped with ILS.
Once I have been in situation where we were bound to Tamanraset Airport(Algerie) in desert.This airport has ILS installed on one runway and VOR on the other side.The weather was blowing sand with low visibility (but within CAT I ýls limits) and the direction of the wind was coming directly opposite of the ILS equipped runway.So you can't do an ILS app. with way over your tailwind limits while you can't do a VOR app since the visibility and descent limits were out of VOR limits.

I think brain works associated with experience.So thats why actually I was refering CAT III in "fog" conditions.Which we generally do.

About the "experienced captains",you're true . I 've been in situations where I took the informations of capts (who acts like an Astronout near the young F/O's) as 100% correct and shockingly surprised how these "astronouts" can forget very crutial details after not reading books any more but flying with instincts and experience.

I didn't want to sound inpolite in my first post also but if you read your post one more time with your pilot jacket on you'll understand why I am surprised.I'll be glad to host you in Ýstanbul and the Fosters are on me :ok:

alf5071h
27th Mar 2004, 11:07
There appears to be plenty of room for confusion in this thread.
First 80/20 is correct with respect to crosswind values in the AFM. The manufacturer publishes max demonstrated crosswinds for manual landings. Operators can apply for alleviation / interpretation from the authority, but I would not recommend pushing any demonstrated limit. All crosswind limits should be revised to lower values for wet / slippery runways as advised by the manufacture.

Autoland performance (certification) is a complex mixture of aircraft actual demonstrated landings and simulated landings – touchdown in the required box – narrower than the runway width. AFM statements vary by national authority; for some the autoland crosswind clearance is a hard limit (the JAA?), for others the value may only be the demonstrated value (the FAA?). Recently the major authorities met to harmonize the regulations and I suspect that hard limits now apply universally and are hidden in statements such as “ Limitations on the use of the system and crew procedures to be incorporated in the aeroplane Flight Manual;” from JAR AWO 309 (f).

My second point is that there is a hint of confusion between dual channel ILS ground installations; a must for actual conditions, and dual channel autopilot systems. I do not know if the 737 can autoland on a single autopilot channel (I doubt it, but I am prepared for education). Both channels of dual channel systems that I operated had to be operational so that in the event of a failure the auto pilot failed soft i.e. the aircraft was approximately in trim. I do not know of any autoland systems that are cleared for hard fail landings even during training. Further confusion and alternatives may exist with degraded triple or dual-dual autoland systems, but again I do not think that these apply to the 737. Also, additional crosswind limits may apply to those systems with ground rollout capability – defiantly not the 737.

Thus my advice follows wing737, revise your technical knowledge of the system, read the AFM, and stay with the published limits – hard or demonstrated.
Thus to answer the original question, the actual weather should not change the autoland crosswind limit (excluding ground roll out systems); the overriding factors are the autopilot capability and level of failure protection. A bit like some pilots?

30kts in Cat3? Unfortunately yes; fog at St Johns NF, and blowing snow at Keflavik. However without the appropriate takeoff limits for a slippery runway the conditions were observed from the comfort of the bar.

LEM
30th Mar 2004, 17:49
If you really are a professional you should know that these forums are not the place to sharpen your technical knowledge.(


Rubbish!

If you are really an experienced professional you can immediately feel the caliber of the various posters, discard rubbish and develop new ideas talking with other pros.

Only if you are a monkey you run the risk of absorbing rubbish in your monkey brain.

Have you really been through the amazing mass of information and stimulating ideas PPRUNE offers?

Often, even an apparently dumb question or post is the spark to provoke brilliant reactions and open new horizons...




Sorry, mr. wing, but a poor village somewhere is missing his idiot, tonight.


:(

calypso
30th Mar 2004, 18:18
I remember a couple of months ago in Keflavic (Iceland) the ATIS was 090/34g44 rwy11rvr 300m OVC 200' together with heavy snow, severe icing and moderate turbulence.

Another aspect not discussed so far is that the 737 autlands maintaining full crab until touchdown. I beleive the main wheels have a few degrees of play to absorb the lateral force. Whatever the visibility a stronger crosswind will put a much heavier strain on the landing gear, this might not show up right away but it may lead to a failure later on (in somebody elses watch...)

wing737
31st Mar 2004, 15:32
"Sorry, mr. wing, but a poor village somewhere is missing his idiot, tonight."

Dear LEM,
I felt very sorry about your poor village,but I doubt they will notice your absence.


For everybody else,
I'd like to repeat that brain works together with experience in some cases.All the CAT III experiences I had were associated with typical fog conditions around Europe.Well I guess you learn a bit more everyday.

Bomber Harris
1st Apr 2004, 01:31
alexban, i read your question with an open mind and i think it is a good question. you know what your ops manual states but you don't know WHY it is much lower than that of a manual landing, and i guess you are wondering what would happen if an autoland was attempted with a much higher crosswind.

to get straight to the point....a manual landing involves the pilot decrabbing with the rudder. there is no rudder channel in the 'stock' 737 autopilot thence the autopilot cannot kick off drift. the aircraft is capable of handling a certain amount of side load on the gear but obviously boeing have decided that 20kts across covers it nicely (that equates to 8 or 9 degrees of crab at touchdown). I believe there is a three channel option but I havn't flown it so know nothing of it's performance.

From a commercial point of view, the vast majority of low vis landings are in foggy conditions with little or no wind. I think it is reasonable to assume that boeing have designed the aircraft to cover this sector of the market. the extra cost of having a rudder channel with runway alignment software in the FCC's has been weighted against keeping the sale price down. the technology is there but boeing made the decision which way to go based on market forces and we have to operate the aircraft based on that.

personnally i wouldn't like to land in a sandstorm with a 35 kt crosswind in 200m visability and be handed control by the autopilot at touchdown (ops manual says disconnect as soon as possible after touchdown) with 15 degs of crab on and then try find the centerline. if the drift had been kicked off by a rudder channel this would be a whole lot easier ( like the md11/tristar/767 etc).

i wonder did all the guys/gals who took the pizz out of your question know that!!!:oh: :)

crvm
2nd Apr 2004, 06:03
AL507,

" I do not know if the 737 can autoland on a single autopilot channel"

Sure it CAN and will even flare but is not approved. One needs only try this in the sim..


Cheers,

Randy

alf5071h
2nd Apr 2004, 07:21
Thanks Randy, but beware of simulators – see other threads, simulators may not fully represent the aircraft or the auto-land system during unapproved operations. They are only computerized representations.

If any one was thinking of trying this in an aircraft then you will be taking some serious risks, in that any single failure in the auto pilot, ILS, or rad alt, etc may maneuvered the aircraft harshly or not flare at all; do not experiment with aircraft.

Thus we differ in our definitions of system capability; I don’t believe that an auto-land system can land (flare) on a single channel unless it is certificated to do so safely.

Bomber Harris
2nd Apr 2004, 23:00
Sorry crvm....have to contradict you on the model I am familiar with.

The 737-800 autopilot will disconnect at 158 feet rad alt with single autopilot engaged (certified 'minimum use height' by boeing) and will also disconnect with both autopilots engaged but failure to recieve flare arm annunciation at approximatly 350 ft rad alt. this would occur only if the was an FCC problem...not a normal scenario obviously.

As long as you don not get flare armed the aircraft cannot autoland.

Ref boeing ops manual ch4 page set 20

alexban
6th Apr 2004, 09:33
BH : you are right,the plane won't do an autoland on one autopilot,but on classics,I think it won't disconect by itself,it will just slamm on the rwy,having no flare capability.The AT will retard though,at 27 feet,so a very hard touchdown.
Regarding your pertinent answer about the crab position,one question:why not trying to use rudder peddal during flare,to remove the crab angle? Never tried that,just a question.
And also,the book says that you can toucdown in a crab position,then removing crab,on a wet rwy.I did this once,on a dry rwy,:} ,due to very strong crosswind with gusts,not the nicest soft landing,but a good one.We did taxi after that :)
Brgds Alex

calypso
6th Apr 2004, 21:02
An extract from our procedures:

AUTOLAND
The Autopilot flies the aircraft onto the runway with a rate of
descent of approx. 150 ft per minute and without removing any
drift. This is a safe manoeuvre up to the autoland crosswind
limitation. The Autopilot must be disengaged at or shortly after
touchdown. If the autopilot is left engaged it will lower the nose
gently but if there is any crosswind there is a tendency for the
upwind wing to lift.

Rudder must not be applied prior to touchdown as the autopilot will apply aileron to counteract this input and the aircraft may drift off centreline. In addition, manual rudder inputs may lead to roll
oscillations and increased touchdown dispersions. Any drift that
was present on touchdown should be removed gently by rudder
after both main wheels are on the ground. Reverse thrust and
brakes/autobrakes should be used as in the manual landing case

crvm
8th May 2004, 05:45
Bomber Harris,

Ah you think so? If that is the case (sure at some points this is true but we are only talking about S CH autolands) but what about the *confidence check* in single channel? Certainly your 800 preforms this even with a single A/P! And you can try this one ;-) . So why would it perform this if it's impossible not to autoland in single channel? (I am not saying anyone should EVER do it but only that it can)

Like I said, Boeing does not want to give any false impressions here so that is why FLARE is not on the FMA but it will autoland. Sure you do not want try this on the real bird but one can ask Boeing (already did ;-)).........

Crvm

alexban
9th May 2004, 09:40
crvm:
sorry mate ,but you got it wrong about this so called 'confidence check'
This check,done at 1500' has nothing to do with single or dual channel autoland.
'The ILS deviation monitoring alerts the crew of excessive LOC or GS deviations.This alerting function is operative during SC or DC A/P ILS approach. The alerting system is armed when the a/c descends bellow 1500' RA with LOC and G/S captured.This self-test generates a two-second LOC and G/S deviation alerting display on each EADI.'
So ,as I said it has nothing to do with autoland or manual land.
It is just an ILS 'confidence check' if you want.
Regarding DCh app,shortly after capturing LOC and G/S ,and below 1500' RA ,the second A/P couples with the flight controls,and FLARE armed is annunciated.
You'll probably ask why 1500'? My guess , at 1500' RA you must be on ILS, this is generally near the OM ,very close to RWY for a unstable app.The ils deviation will autotest,also the a/p's systems will do an autocheck at aprox 1500'.But you can select both pilots till 800'RA.
You said you asked Boeing about autoland on SCh ? he,he...
And what did Mr Boeing say? FLARE not armed,then no flare and touchdown capability available,no bias trim also. (as he says on the OM) ,and the plane wiil land on the rwy?! :)))
That is correct.It will smash on it with 700' ROD.Nice landing.


Like I said, Boeing does not want to give any false impressions here so that is why FLARE is not on the FMA but it will autoland. Sure you do not want try this on the real bird but one can ask Boeing (already did ;-)).........

:) kids ,we are proffesionals ,don't try this at home,you'll wreck your FSims.
what false impression?
Brgds Alex