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From: Gary Casey <glcasey@adelphia.net>
Subject: Re: enough runway

>
A few comments on runway length:

I certainly agree with Mark's comments below - I've never seen a time  
when getting on the ground, realizing there was not enough distance  
to stop, and then deciding to go around worked.  If the remaining  
distance is so short that the plane can't be stopped after the tires  
touch it is almost certainly too short to make a successful takeoff.   
I have read about any number of accidents where the subsequent  
takeoff was unsuccessful, including one double fatality in a IV.

The traction coefficient between the tire and the runway is certainly  
better than any other combination available(retracting the gear??) -  
reminds me of the old biker tale about "laying it down" to stop.   
Their theory must have been that the traction between skin and  
pavement was better than rubber to pavement.  The tire is the best  
way to stop the plane.  This is, on dry paving at least, irrespective  
of the size of the tire.  Granted, a huge tire with soft rubber might  
have a slightly better coefficient that our hard rubber, high  
pressure tires, but not by much(10%?).  And it doesn't have much to  
do with brakes as long as there is enough brake pressure to lock the  
wheels.  In fact the best approach when faced with a real emergency  
is to just push as hard as you can and lock up the wheels.  On dry  
paving the coefficient doesn't drop off a lot when sliding and the  
pilot will almost never be able to perform an optimum "anti-lock"  
function, so there is no point in trying.  If stopping on a runway  
with standing water (or ice) you really do need an anti-skid, but is  
it worth adding an electronic anti-skid system?  I don't think so,  
but others might disagree.  In short, rubber is the best stopping  
media and the technique is to get the plane on the ground, even if  
too fast(brakes will slow the plane much more effectively than  
floating just above the runway), apply the brakes, get the nose down  
and the flaps up while the stick is held full back and hope for the  
best.  I think you'll be surprised how fast it will come to a stop,  
although the tires will probably need to be replaced.  All you have  
to do is ride (if you're driving you already know this) a 737 into  
Burbank to witness the technique in action.  Invariably I will here  
some passenger say "that was a terrible landing" about the time I'm  
thinking "that was a great landing."  Granted, with hard braking  
there may be only 50% or less of the plane's weight on the mains, but  
that is still the best way.

In my opinion drag chutes aren't worth talking about, but reverse  
thrust might do some good, although with the added work load there  
might not be an improvement in real life("oops, the runway is too  
short - stand on the brakes, get the flaps up, prop past the detent  
to reverse, wait for the blades to change, add throttle...oops I'm  
already stopped").  I don't think the engine would care about having  
the pitch reversed.

Gary Casey
ES N224SG
> Guys,
> It takes MORE runway to do a touch and go than to full stop.
> I suggest that if anyone wants to experiment with any such  
> techniques they
> do it on plenty of runway.
> I have flown into runways as short as 1800 ft with trees at both  
> ends.  The
> minimum runway I need to land, reconfigure flaps, add power and go  
> is more
> like 3000 ft.
>
> Also, I think a drag chute would be impractical.  By the time you  
> realized
> you need it, your speed would be low enough that it wouldn't do  
> much good.
> They are for planes that land at 175 kts.
>
> Mark Ravinski
> N360KB  1399 hrs