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Beechjet Anti-Skid Off on the Rollout???

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Never turn A/S off on rollout!

Aspiriring I can't tell what you were saying. I'm not sure if you were quoting something or what you were saying.

A/S in a citation puts a annuciator light on the panel. Anything below 15-12kts turns the a/s off. Why would you turn the a/s off? The ntsb would love the fact that you turned the a/s off right before you slid off the runway.

If the system fails it fails. At least the switch will be in a position it was supposed to be in. Check the numbers for a landing anti skid off. It's a long number.

We aren't talking 75''s and that sort. We are talking beechjet's and that size.
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I was not trying to be disagreeable. In a previous post I said that you should never turn the A/S off to improve stopping distance. The min stopping distance is achieved by using max braking and let the A/S work to prevent hydroplaning. That is an undeniable fact.

I was responding to a post where the person said that it would take a lot more runway and you would probably blow your tires. This is just not true. On a dry runway using normal procedure you should not have any trouble. I will say again that if you cause the A/S to active on landing on a dry runway your procedure, well sucks. I do not care if you are flying a B-747-400 or a Cessna. If you land other than an emergency condition and have to use max breaking thereby requiring the A/S to prevent hydroplaning you have made the wrong decision or selected the wrong airport. I stated that landing on a contaminated runway the activation of the A/S can on occasion occur.

Yes landing without A/S requires more runway but a clean runway it is not that much and you should not blow your tires. Can you blow your tires, yes, but to me the real danger or concern about landing without A/S is flat spotting a tire. Some of the larger aircraft even with A/S you can still flat spot a tire. Flat spotting a tire and blowing a tire are two different things. Like I said I would not land a Hawker without A/S on a contaminated runway of 5000 feet or less but I would land without A/S on a dry runway of 5000 feet.

If you look at the numbers say for a Hawker, landing wt. 21000, standard day, sea level, calm winds the landing distance is 2473, landing field dry is 4121, landing field wet is 4740. You can almost land the Hawker on a dry runway of 5000 feet and landing weight of 21000 lbs and never use breaks. If you land without A/S the penalty would be applied to landing distance and not the landing field. It would affect the landing field but the penalty would be applied to the landing distance. Why anyone would ever think that max breaking would be normal is beyond me. Have you ever had the A/S to activate on landing on a dry runway? I do who hope not.

My previous response was to the poster that said it was such a big deal and that you would blow tires, etc. Sorry but I believe that is just not true. I would be willing to make a bet that I could land and stop any aircraft with reasonable runway without A/S without blowing a tire. I am not the ace of the base and I hope that most pilots could do the same. Yes if I was operating the sim I could hit the button that says blown tire but that is a compound problem and not one that should be cause by the fact that you landed without A/S.

Now bottom line and I state again you should never turn the A/S off in any aircraft to decrease stopping distance. Min stopping distance is achieved by using max brakes and allowing the A/S to prevent hydroplaning thereby given you the min stop distance.

I do believe that landing on a contaminated runway you should as a normal procedure use aerodynamic breaking until you are well below hydroplaning speed for your aircraft before using any brakes. If you find that you must use brakes above hydroplaning speed you again are some place you should not be. I only made the statement that on contaminated ramp I like to turn the A/S off due to the fact that I have seen the A/S activate at low speeds where it was supposed to be auto off. I am not saying that I think it should be normal procedure. I am saying that I do that and I will continue to do so. I have several things that I do that I do not expect all to do, I am sure all I do is maybe not the best thing. Many times as I approach a gate where the ramp is very slippery I will open the reversers and even use reverse thrust when on a down slope. I have had to do this several times on large aircraft to be able to stop without hitting the terminal.

It might not be a procedure in the book but I know that most all aircraft with reversers will back up. Now I am not saying that backing up an aircraft is normal procedure but in some aircraft it is approved procedure. I also am not trying to give lessons, but I do not believe that landing without A/S is a big deal. I do not believe that landing without A/S will mean that you will blow your tires. I do believe that taking off without A/S is a much bigger deal. I would want a bunch of extra runway for takeoff. I do not believe in scare tactics such as you will blow your tires. I do not think the poster really meant it as a scare tactic but that is the way it came across to me.

Normal abort procedure will be changed. Some types (maybe only larger types) use auto brakes for abort, without A/S you could not arm the auto breaks. All of the auto brakes that I can think of are activated by reverse thrust above 80 knots. Not being able to touch the brakes on abort is difficult when you first start training in such a system.

Gereral statement never land an aircraft with 4 mains or more with more than 1 A/S release light on with the A/S on. Never land an aircraft with only 2 main wheels with any A/S release light on with the A/S on.

While flying with some of the younger pilots the biggest fault that I find is the reliance on auto systems and computers. Steam gauges still work for me and I believe in them.
 
Boy you guys are long-winded! Here's what this guy's thinking about turning off the anti-skid... Locked-up wheels produce more friction than rolling wheels on dry pavement, so therefore an airplane should stop sooner with the wheels locked up than rolling. The problem is, the wheels cannot maintain this condition for long due to heat build-up and the eventual tire failure, in which case the end result is longer (and more expensive) stopping distance required.
 
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Not really true. You can hydroplane on rubber so it depends on the speed you lock up your brakes. I do not believe that you can not stop quicker when you are skidding. Maybe from a very low speed it would be true. Tire failure as I have seen, from heat buildup, occurs several minutes after the braking action is completed. This is one reason for fuse plugs. Fuse plugs will blow when the heat build up is sufficient and save the damage that could result if the tire blows from heat buildup; a control blowout is really produced.

I have seen it take 10 or 12 minutes after landing for a fuse plug to blow. One case I remember I met the aircraft at the gate and had started a pre-flt and was in the area of the gear when a fuse plug blew, scared the hebe gebbies out of me I can tell you.
 
Aspiring to be said:
Not really true. You can hydroplane on rubber so it depends on the speed you lock up your brakes. I do not believe that you can not stop quicker when you are skidding. Maybe from a very low speed it would be true. Tire failure as I have seen, from heat buildup, occurs several minutes after the braking action is completed.

True... Eventually the tires could start hydroplaning on boiling rubber, until there was no rubber left, to be followed by a blow-out. Then there is the other kind of blowout due to a melted fuse plug, but this has nothing to do with the anti-skid system and more to do with landing at excessive speeds or insufficient rollout which will overheat the plugs to save the tires from exploding.

In any case it is never recommended to turn off the anti-skid for normal takeoffs and landings. It is, however recommended to be turned off for taxi in some aircraft... where much lower speeds are involved.
 
I hesitate to jump into this mess, but here goes. Back to the original question of some BE400 guy saying to turn off the anti-skid if things get hairy. He probably flew the old Diamonds (MU300) without T/R's. If you have ever flown one you would know the brakes suck. On a contaminated runway, they WILL cycle and once they do, you have no choice but to stay on them unless you have a really long runway in front of you. The 1st cycle is a lonnnngggg one. The brakes just realease and you count to 10 (seems like) waiting for your brakes to come back. When they do, you need to apologize to you pax for the series of whiplash maneuvers. The problems were pretty well worked out in the Beechjet. I do know guys that would turn the A/S off if they got scared in the MU300 but to tell a new Beechjet crew to do it is not right.
 
AntiSkid

If the performance was better without anti-skid, then why did we ever put it on airplanes? The fact is the performance is greatly enhanced and this guy is taking a real chance.
 
Other possibility for why this stuff happens:

Some guys have a deeply held need to be smarter than the test pilots, engineers, whoever.

Book calls for .76M, they have some co 'n bull reason why .77M is far superior. The rules/methods change on every leg, so that you can never figure out their black magic. Wearying.

Not necessarily true in this case, but it happens all the time.


Quote from rice:
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Here I sit just shaking my head!
Some yahoo is out there flipping off the anti-skids for apparently no good reason, flat-spotting tires, costing some company lots of dollars and generally making a fool of himself.
And I'm sitting here behind this f%*$en geek machine for the 76th day after being laid off!!!!!! Some things just aren't right in this world.
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Amen.
The weed-out process in this biz never seems to work properly does it? I feel your pain.
 

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