landing jet on Snow covered runway ABS or none

[Pace]

Writing this from Eindhoven. had to divert in here this morning in heavy snow as destination went down very quickly.
Here was 300 feet and 800 meters and the runway had white out with snow.
Runway was long for a citation so I braked very carefully feeling the ABS unlocking the wheels.
On snow covered runways or icy runway are you better switching ABS off?

pace

[Lord Spandex Masher]

If its that bad I'd give it full reverse and max braking (man or auto) effort with anti skid.

[moonym20]

I'm not sure the thrust attenuators double up as effective reversers ;)

[Gulfstreamaviator]

1/2/3/5 etc mostly had REVERSERS, not attenuators.
Only CJ have attenuators.

I think

Glf

[Pace]

This one is a 550 and no reverse thrust.
ABS is normally a bad idea on snow or ice and it can be switched off! But cannot find any reference to ABS on or off on snow or Icy surface ?
Normally clear of runway after landing or below 30 kts it ABS off anyway.

Pace

[deefer dog]

I seem to recall that under 5kts gs it will not work - simply locks the wheels. Long time since I flew the 550 but there should however be a reference to it in your flight manual or the POH.

[Trim Stab]

The anti-skid system on Citation aircraft is not as sophisticated as ABS on you average family car, so beware!

ABS on even a cheap car will brake the wheels until adhesion is momentarily lost, then momentarily release the brakes until adhesion is regained, and repeat the process until brake pedal pressure is released by the driver. The result is high frequency cadence braking, whereby the car tyres penetrate water or light snow and remain in contact with the tarmac, giving maximum braking deceleration.

The anti-skid system in Citations just assumes a skid is about to occur if the main gear wheel rotation speed drops below what it would be if the aircraft was taxying (in dry conditions) at fast walking pace, then opens a valve to reduce the maximum brake pressure the pilot can apply. So if the pilot brakes hard on a slippery surface causing the wheel rotation speed to drop below the preset limit, a valve opens reducing the hydraulic pressure in the braking circuit, until the rotation speed increases above the trigger point again. The resulting braking effect is nothing like as effective as car ABS, as the tyre can continue to aquaplane.

So if you really need to stop quickly in heavy rain or light snow in an emergency, turn off the anti-skid. You will at least have a chance that the tyres might bite through the water/snow to the surface below. You might have a job maintaining directional stability, and might well blow a tyre, but you will have a better chance of stopping.

Obviously this is not what Cessna recommend. They would rather you skid off the end of the runway and die in a fireball so that their clever lawyers can blame you for landing on an inaccessible runway.

[Pace]

Eindhoven is long so was not worried a outrunning out of runway. A 737 landed behind but yes the runway had a complete cover of snow and the brakes kept releasing.
It was then best to take your feet off brake pressure and reapply.
It crossed my mind in the rollout to flick the ABS off

Pace

[Lord Spandex Masher]

Pace, I didn't spot that you were talking about a citation, (yeah I know, RTFQ!).

Disregard post two as its what I'd do on the 737.

Sorry.

[Soave_Pilot]

Obviously this is not what Cessna recommend. They would rather you skid off the end of the runway and die in a fireball so that their clever lawyers can blame you for landing on an inaccessible runway.

nothing but the truth...

[NuName]

Not anywhere near as fantastic as your reply though. I have read it several times and have no idea what you want to get accross to us, "keep just out of virtual trouble when you have time" whats all that about??? Cute???? Proud?????

[His dudeness]

7th Dec 2012 13:56

Writing this from Eindhoven. had to divert in here this morning

somebody lands the bizjet on the alternate and not the destination and the first thought he has is to post via his phone on pprune and express his thoughts and doubts about antiskid on snowy runways


Q:Whats more dangerous than no Anti-Skid ?

Jumping to conclusions...

[Richard Westnot]

I cannot believe some of these replies.

Pace, I don't fly a Citation but I would have thought using the ABS option on a slippery surface would be a good idea. But what do I know. Maybe I will learn something from some intelligent replies.

[Pace]

Aerobat 77
Fail to see what is funny? We had to divert due to a number of airports being closed as did quite a few other aircraft!
Eindhoven was offered which has a long runway for something like a Citation!
A 737 landed behind us so I would be more worried landing that on a runway which was pure white.
The anti skid was struggling meaning I was very gentle on the brakes releasing and reapplying!
Normally on cars anti skid does not do a good Job on snow or ice !
On the Citation you can switch anti skid off!
I wondered in those conditions whether anti skid would have been better on or off.
I do have pictures of the conditions which I can put up so you can see how realistic MSFS has become nowadays

Pace

[Desert185]

The antiskid was doing what it is supposed to do...release to avoid locked wheels. I wouldn't turn it off, or you would increase the likely possibility of a flat tire should you experience a portion of the runway with increased friction.

No reverse is a big issue in a jet on a contaminated runway. You would be better off shutting down an engine to reduce idle thrust on the rollout than turning off the antiskid...in my opinion.

[bluesafrica]

Can't remember if it was early Citation or Mitsubishi Diamond but in any rate anti skid was "working" by releasing the pressure in a very quick manner until the brakes were completely gone. After releasing the brake pressure the same cycle was completed. More than once I was switching the anti skid off on slippery iced up runways.

[His dudeness]

The anti skid was struggling meaning I was very gentle on the brakes releasing and reapplying!

I was told that releasing and reapplying is contra-productive.... but I remember that I once flew 550-0028 and on this one something was different from the higher S/N I used to fly. Can´t remember the difference though...


This is from the CJ3 FSI Manual since I´m to lazy to go to the cellar to dig the old 550 manual out...

To ensure optimum braking on water, snow, and ice-covered, hard-surface runways and all unimproved surfaces, it is necessary for the pilot to apply maximum effort to the brake pedals throughout the landing/or abort run.

Normally on cars anti skid does not do a good Job on snow or ice !

Don´t think I agree....tested it yesterday and today, works mighty fine....

Bosch ABS - The advantage - YouTube

[Pace]

What to keep a troll kid amused ?
I am sure you have MSFS to go and play with and keep you amused.

worries with the big paying passengers and the company than to think about the use or no use of antiskid and post it here via phone entirely from the airport .

Just shows your utter ignorance of corporate flying! Once the PAX are dispatched we often have hours of boredom awaiting their return and either post to pprune on the computers in the pilot lounge or YES an I phone.

Pace






Pace

[midnight cruiser]

Car ABS is designed to facilitate steering under breaking on slippery surfaces. It is well known that car ABS slightly decreases the maximum deceleration possible, but it allows you to steer round a hazard. We don't need to do that in the same way.

I have never come across an aircraft anti-skid which judders the brakes on and off - They have always applied the maximum braking to just short of the point where it would lock the wheels, and held that braking force. This gives the maximum deceleration.Turning off the anti-skid seems a bad idea to me.

[sooty3694]

Aerobat77, what was the point you were trying to get across? What so cute or funny about the post?

The guy landed on a snow covered runway and asked what to me seemed like a reasonable question. Apart from stating the obvious (maintain directional control, and a misspelt reference to runway length), your post served no useful purpose, so why highlight to everyone that you probably DO only fly Microsoft products?

[safetypee]

Pace, et al, see ALAR Briefing Notes (http://flightsafety.org/current-safety-initiatives/approach-and-landing-accident-reduction-alar/alar-briefing-notes-english), chapter 8 onwards.
Also see Managing Threats and Errors During Approach and Landing. (http://www.skybrary.aero/bookshelf/content/bookDetails.php?bookId=874)

[sooty3694]

Aerobat77, what was the point you were trying to get across? What so cute or funny about the post?

The guy landed on a snow covered runway and asked what to me seemed like a reasonable question. Apart from stating the obvious (maintain directional control, and a misspelt reference to runway length), your post served no useful purpose, so why highlight to everyone that you probably DO only fly Microsoft products?

[Pace]

MSFS aerobat 77

When yoiu were doing your medical flights in MSFS on your computer where did you get youir weather.

From RyanAirs site for that day many delays and diversions
Are you 12 or older?

7 Dec - Possible Weather Disruptions - Europe


Snow is forecast on Friday 7 December across Northern France, Belgium, Holland and Germany and flight operations may be affected. We strongly advise passengers to check the status of your flight on Ryanair.com


7 Dec
08:55
Snow. Low clouds. Chilly.
0 °C
14 mph
100%
998 millibars
Maybe you can post the actuals for that arrival time as I cannot be bothered

[His dudeness]

METAR EHEH 070855Z AUTO 15012KT 1300 R22/1000N -SN SCT005///
OVC006/// M00/M00 Q0998 AMB 15013KT 1000 -SN SCT005
SCT008 BKN012 BECMG 9999 NSW FEW006 SCT009 BKN012=

Almost VFR you pussy! ;)

[His dudeness]

He landed in Eindhoven on a slippery runway AFTER diverting. And he has not disclosed his intended destination.

And the wx was bad enough in EHEH, btw he never said he was below minima in EHEH. Pussy followed by the smiley meant not that I think he is a pussy.

You can turn and twist all you like, but your posts were not in shape, type or form helpful nor polite or in a way one could expect from a 35 year old pilot (if you are indeed a pilot?)

[mad_jock]

Pace have you got a Maxaret system on your jet?

Can't turn it off on my type even if I wanted to but I wouldn't to be honest unless your flight manual tells you to or gives you the option and you have performance for it off.

[Artie Fufkin]

aerobat77, have you visited a website called engrish.com (http://www.engrish.com/)?

It really is jolly funny!

[Pace]

MJ

It's on the checklist to turn it on lining up and off clearing the runway!
I was told below 30 kts as it a pretty archaic anti skid system.
12 years ago when I flew as an FO on a citation we nearly ran off the taxiway with the anti skid on taxiing.
The Captain screamed he had no brakes and I pressed my side felt like brake fade on a racing car then thankfully came on with a bang.
While I have landed twins on snow covered runways never a jet and it crossed my mind on the rollout whether it would be better off than on but I left it on until we cleared.
One poster made a good point about the danger of flat ting a tyre if the tires found an area of grip with anti skid off.

[mad_jock]

A feature of the maxaret system is a spinny disk thing inside the hub and if its leaking you have to pump like hell to keep any pressure on what ever speed your doing.


I think it was one of the first ABS systems and not very popular and never made it to cars.

Might be worth finding out what system you have on the aircraft. The type of sensor, method of processing the data will give you a clue why its rubbish while taxing.

[sooty3694]

preventing flat / exploding tyres is the main reason antiskid was introduced at all.

pure braking action on snow will be best with antiskid off and locked wheeles. the tyres will then tend a) to grab down to solid ground and b) build up a bigger and bigger hill of snow infront of them.

forget the flight manual and POH - aerobat77 seems to be the expert on everything to do with aviation judging by the forums here.....quite rare to find such an expert at his young age.

[aerobat77]

huh ?

my only expertize tells me sooty is a little bit tensioned - take a hot bath and try to relax :).

cheers

[mad_jock]

Stop being a prat Aerobat.

Every first year engineer knows that you will get between 0.6 and 0.8 coefficient of friction for a tyre on a dry pavement surface. When the forces involved are when the tyre is under a static load with zero relative velocity between the surfaces.

It drops to below 0.1 which there is a dynamic situation when the tyre starts skidding.

The point you want is a very small zone between the transfer of static to dynamic which is when there is a little bit of unstick between the surfaces but not complete.

Racing drivers try and operate in this zone with varying success rates.

For mear mortals mechanical or electro mechanial ABS systems will control the brakes being in the near optimum band far better than they could.

There are other reasons for not wanting the tyre skidding mainly to do with the fact because of the drop in friction coefficent you will be more exposed to laterial forces moving you sideways which will mean in a aircraft context you may be able to keep it pointing directly down the runway but you will be blown off the side by a crosswind or get some nasty moment effect causing the aircraft to spin due to wind cocking and the nose wheel still having a static grip on the runway.

[aerobat77]

the statement about the braking distance refers only for snow . the same would apply for braking on lets say sand / gravel.

i paste you a sentence from wikipedia .

In gravel, sand and deep snow, ABS tends to increase braking distances. On these surfaces, locked wheels dig in and stop the vehicle more quickly. ABS prevents this from occurring

here is the whole article

Anti-lock braking system - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Anti-lock_braking_system)

this does not mean somebody recommends to switch it off because the benefits of antiskid apply even when braking distance is increased in some conditions .

cheers and keep on going :ok:

[mad_jock]

If you were a pilot of any knowledge on white runways you would know that you don't land on deep snow.

It may be white but the surface is either ice that has been chopped to increase the friction or they put hot sand down that then melts into the surface giving a shell grip effect or they just brush it when the friction is high enough anyway.

You can have up to 130mm of snow dry on top or 13mm of wet slush.

Otherwise you can't land.

Even 100mm on Paces titchy tyres on the Citation isn't really deep. And if you did get into a depth of snow which would have that effect you will more than likely not need the brakes at all. The aircraft will come to a stop on its tod with no braking at all, and you won't be able to clear the runway taxing. And I suspect that he would not have enough power to over come the drag to takeoff.

After a quick google

Coefficients of Friction for Snow (http://hypertextbook.com/facts/2007/TabraizRasul.shtml)

It turns out that dry snow is 0.53 to a wacking 1.76 which you should know is Good. No penalties for landing but huge for depature.

[NuName]

I guess you are assuming we don't need to worry about directional control. Your lack of common sense is quite stunning, but you are entertaining.:p

[sooty3694]

a quick look through tech log will show that aerobat 77 has been advising those who fly Boeing and airbus on a wide variety of topics also.

perhaps when he progresses from flying his microsoft-medivac he'll incorporate the wiki skool of flying?

[mad_jock]

As well as front wheel bias braking.

The lack of spin up.

CofG in front of the application of braking force.

Tri point under carrage

So many things which are different compared to a 4 wheel car.

[aerobat77]

uh... now i started to rise the mental emotions here i see... :rolleyes:

i,m wondering if somebody can really be happy to live in an obscure dream wishes world and claiming in an open anonymous forum to be somebody who he would like to be.

the same of course applies to the tons of boeing / airbus drivers with 20000 hours . techlog reached practically 100% obscurity , but sometimes with a worth reading character of it.

be yourself gents , don,t show so obviously that life frustration and aggression are married . :8


@ nuname : i related purely to braking effect of the wheels on snow, excluded all other aspects like e.g directional control. at the end of the day it means : when you have anstiskid and the poh call to activate it for landing - do it !


:ok:

[mad_jock]

You really are a chump aerobat77

Have fun in your little dream world. And your wrong about the snow bit you have to add in deep snow for it to be correct.

[aerobat77]

its really pprune on its best gents . maybe you notice that you offend me personally while i,m do not offend anybody specific.

relax and be yourself , in regards to the dreamworld you accuse here !you know it...

cheers

[mad_jock]

Nah we are just put out that some one pretends to be knowledgable and part of a industry and job that we all worked hard both from a training point of view and experence to get where we are, really hasn't got a clue.

Then some prat comes along and starts talking rubbish then gets into a come on lighten up when its pretty obvious that they are clueless.

We are just making the call that you are talking rubbish and want to make sure that anybody that is on the road to becoming a pilot isn't diverted away from factual knowledge by your spouting of rubbish.

[aerobat77]

amen mad jock :E

in real i would suggest to kick during taxi in snow the brakes firmly with and without antiskid to answer something you debate for days in 10 seconds .

but suggesting such a think here gives of course no result . so keep on debating .

[His dudeness]

Except that the antiskid does not work at speeds a sane person uses to taxi around when the aprons/runways are snow covered.

[mad_jock]

There really is no debate on our opinion of your good self.

As his dudeness points out there is a distinct lack of practical knowledge of actual operations.

[Richard Westnot]

I cannot believe some of these replies.

Pace, I don't fly a Citation but I would have thought using the ABS option on a slippery surface would be a good idea. But what do I know. Maybe I will learn something from some intelligent replies.


Well, what have I learnt................

Put aerobat77 on the "ignore list"

Thanks mad jock, His dudeness and others for the decent responses. You learn something new everyday :ok:

[sooty3694]

Aerobat 77......I think you are a fraud. How could you possibly be a REAL professional pilot when throughout this thread you have demonstrated ....

a) that you certainly have not even attained English Proficiency level 1, and
b) that here, and on tech log, you continue to be slagged off for writing utter rubbish?

Now if I am wrong, please take up the issue with pprune, and see if you can get a court order to identify me. On both fronts I cannot imagine how it could be proved otherwise....you are a troll, and a misinformed one!

[sooty3694]

on second thoughts......perhaps you have a drink problem to explain away your English grammar - or rather lack of it?

[mad_jock]

piss off sooty :p my grammar ain't that great, spelling either.

[mad_jock]

:D you can still see the taxiway markings ya big girls blouse.

What was the breaking action?

[Pace]

MJ

Runway as posted was pure white taxiway was better have a still shot of runway if I can work out how to put still pics up here ;)

I will throw a snowball at you if you call me a girls blouse :E

Obviously the runway was too much efforts so they just made nice taxiways? :{


Pace

[mad_jock]

Girls blouse.

Discovered that once its below -10 you can't make snowballs the snow is to dry and you can't get them to stick together.

To be honest I quite like it when its perm under -5 its this pissing about freezing then unfreezing thats a pain.

[Pace]

Buy the time we were ready to go the stuff had stuck to the airframe meaning 220 liters of deicing fluid and a 1000 Euro bill beware deicing :{

Couple of pics here

https://lh5.googleusercontent.com/-EnNH-NE9Upc/UMhlbY4vbRI/AAAAAAAACHY/Sjnya084qlE/s640/IMG_0614.JPG?gl=GB

https://lh4.googleusercontent.com/-Oc3vs1ObUV0/UMhlJOWbaNI/AAAAAAAACHQ/2-69mBZXTWw/s640/IMG_0617.JPG?gl=GB

Looks very Christmas Spirit ;)


Pace

[mad_jock]

Thats a normal day at work for me. Or should I say night.

Been lucky so far only had to de-ice twice. The stuff we are getting is so dry it doesn't stick to anything. Just have to broom it off so nobody takes a photo and post it on PPrune :D

[Pace]

The big bugger in the other shot took forever to deice:{ I know we had to wait.
God knows what their deicing bill came to?

Pace

[His dudeness]

The next time you should taxi under it and be deiced by the dropping fluid... ;)

[His dudeness]

Wellwellwell, acc. to this:

link removed

XXXXX departed Doncaster at 0718 and arrived at 1755 on the 7th.

Granted, he could be a troll that puts his imaginary airplane into that site, somehow I doubt it. When it comes to trolls on here I do have other suspects...

Last time I checked Doncaster was in the UK which still is in the EU....

This took 30 secs to google.

wondering what european operator can use an US registrated citation commercialy and with what kind of licence you fly commercially an US registrated citation with passengers to eindhoven i just googled for it.


Did pace say something about flying COMMERCIAL ?

I read something about corperate in his post.

Just shows your utter ignorance of corporate flying! Once the PAX are dispatched we often have hours of boredom awaiting their return

XXXXX was indeed some time in europe ( UK ) but seemed to mostly dissapeared from european sky after 2011

It was seen in late March 2012 in the UK:

Link removed

And in August too:

Link removed

And in bloody November too:

Link removed

But of course, these could all be fakes...

never ever after landing with furious pax

Where comes the furious pax from ? Your imagination ?

Let me guess, observing is not your strongest point ?

[fjordviking]

Aerobat77 is a troll.
Starve and ignore the troll and hopefully he will find other forums to do his tricks.

[BabyBear]

Pace, I don't know you real world, but for sure I do not question your filght related posts, although I may do others.:p:p

BB

[Lord Spandex Masher]

Buy the time we were ready to go the stuff had stuck to the airframe meaning 220 liters of deicing fluid and a 1000 Euro bill beware deicing :{


Bleedin' Nora! You can do a whole 737 with less than that.

Was the de-icer called Dick Turpin?.



P.S. Do you know what de-icer is?









He's de man who puts de ice on de wings.

[Pace]

BB

You will soon ;)

Pace

[NuName]

A quote from your previous post:

"i,m wondering if somebody can really be happy to live in an obscure dream wishes world and claiming in an open anonymous forum to be somebody who he would like to be."

Sounds like it was written for you, while you are publicly accusing someone of breaking the law you might like to give it a lttle validity by not being anonymous yourself. With a mouth like yours you must be really too scared for anyone to know who you are. GET A LIFE!:ugh:

[Armchairflyer]

Pace, for added fun maybe you should mention that you have indeed worked for one of the best MSFS add-on outfits :E

[Pace]

Yes I have worked with the best addon company for MSFS in the past mainly in trying to get as realistic flight dynamics as possible and had the privalage of teaming up with a genius in the complex manipulation of the flight dynamics engine! His genius NOT mine!

MSFS is a great product with a huge following for people who are not lucky enough to fly real world or who use it to help certain aspects of their flying.
I am sure it has also helped many young kids into a career of flying by stoking their imagination early on.

Pace

[Armchairflyer]

Not merely young kids, it can also seduce old blokes to spend a small fortune just to answer the question how the real experience feels ;)

Point was, maybe this info would have fed the troll an after-dinner mint (for those who know "Monty Python's The Meaning of Life") :E

[His dudeness]

It might be different in the S2 but in a CJ3 if you turn the anti skid off and on again it goes into a test mode during which you have NO brakes for a while. I was taught never to touch the anti skid switch unless stationary for that reason.

There is a difference between the earlier C2 and the newer C2s & CJs. Up to S/N 436 (IIRC) anti skid has to be off for taxi. No self test build into these I think.

[CL300]

Finally, someone is using the proper word of Anti Skid instead of ABS.....


Until we will start braking with the nose gear we will not need ABS...IMHO :suspect:

[Steak&Kidney_Pie]

I cannot believe this is a serious question/thread. I suggest handing your license back to the authority.