Archived from groups: alt.games.microsoft.flight-sim (
More info?)
Marcel Kuijper <zoepetier_nothing_here@hotmail.com> wrote:
> How about take-off from an uncontrolled airport?
Yes, the same applies when a pilot decides on which runway to depart, too.
The pilot is the PIC and ultimately responsible for using the runway at an
uncontrolled airport s/he concludes is the safest.
It is common at uncontrolled airports to have one longer runway and perhaps
one crossing runway that is much shorter. Or, in the case of my real world
across-the-US trip two weeks ago, flying into an airport with one long
paved runway and one crossing turf runway.
In either case it is conceivable that there could be one or more small
aircraft using the small paved or turf runway, whereas you are flying a
heavier, single or multi-engine aircraft that needs the longest paved
runway possible. Thus, no matter how many might be using the crossing
runway, you will choose to takeoff/land on the longer runway for the safety
of your flight.
I'll give you another example: A calm evening with winds 000 at 0 kts. I
was just taking the runway at an uncontrolled airport one evening when I
heard a commuter aircraft (Beech 1900) call that he was 10 miles out,
landing on the opposite runway as I was departing. As my aircraft began to
accelerate down the runway, I saw his landing lights come on in front of me
(albeit 10 miles off).
I simply re-iterated my call on unicom, stating that I was "on the roll on
runway xx, with a south departure, traffic approaching opposite runway in
sight" so that the commuter pilots were confident that I would turn away
from them soon after my departure.
> Since I was climbing out after take-off (in a straight line I might add),
> the last thing I expected was incoming traffic from the same side.
> This made me wonder: was I taking off in the wrong direction or was the
> Skylane approaching the wrong runway?
Neither. When that high (and speaking as if this were real life, rather
than limited AI aircraft), it is certainly conceivable that the Skylane
hadn't yet begun his maneuver for the traffic pattern of the runway from
which you just departed. Or, as I indicated, he may have been on a real or
practice instrument approach.
Nonetheless, neither of you would have been wrong, unless you banged into
each other. Then you both would have been faulted for failing to see and
avoid.
> Yes I was around 4000ft above the airport elevation, but the Skylane was
> coming down from his cruise altitude and it was heading towards me.
> And that's what sparked this thread.
There are no street signs in the sky. Aircraft can and do approach from
any direction, especially when considering climbing and descending
aircraft. I type it again, because it is so true: See and Avoid.
> Okay...maybe I shouldn't have switched to the Center freq. so quickly.
> From now on I'll stay on the Traffic freq. until I feel it's safe to
> switch.
Or, continue to monitor the unicom frequency with the second radio while
communicating with ATC on the first. However, listening to the radio does
not guarantee that you will have a totally correct picture, since there are
aircraft flying about legally that do not have radios (in class E or G
airspace, of course).
> Wouldn't that depend on the country this is taking place in?
> At EHLE for instance (one north-south asphalt runway), the wind direction
> decides from which way one should fly in and it's up to the controller to
> inform the pilots what the wind direction is, so one doesn't fly in on 23
> while the other is taking off from 5.
Now you are mixing controlled airports with uncontrolled airports. IIRC,
your primary question that started this thread pertained to uncontrolled
airports. The PIC determines what runway to use at uncontrolled airports,
based on several criteria, not the least of which is whether there are
other aircraft already in the pattern or not.
At controlled airports, wind direction *most often* determines runway in
use, but even that rule does have exceptions. For example, if the winds
were, say 5 knots straight down a runway, ATC could choose the opposite
runway if municipality noise abatement rules required them to do so. A 5
knot tailwind will not have any relative effect on a larger jet aircraft
and the runway length will more than compensate for smaller aircraft.
> We're talking about a few degrees deviation either way, so that by itself
> shouldn't have that much effect on the plane....
Nope, it shouldn't, but I was assuming by your example whether you were
wondering if headwind/tailwind components determined take-off direction. I
was simply pointing out that in your example, you had a tailwind component
when you departed runway 27, which may have contradicted what you believed
was the proper runway to use based on wind direction.
> but I like what you're
> saying. 0-179 degrees for runway 09 and 180-359 for runway 27.
> Simpley use the same principles used to determine an even or odd cruise
> altitude. I can remember that!
> This problem should no longer be a factor!
Sure, that problem works out cleanly for runways 09/27, but what about
single strip airports with runways 15/33? How about 1/19? The point is
that you may need to come up with a more generic rule of thumb for quickly
determining landing/takeoff direction strictly in a headwind, if that is
even possible.
I mentally calculate the headwind component by comparing the runway number
to the reported winds (if the uncontrolled airport has an AWOS/ASOS), or
quickly see the headwind/tailwind by observing the windsock/tee.
> Uhm....I gotta ask this....doesn't that go against all the training manuals
> there are out there?
There is the theory in training a primary student, and there is the
practicality in flying for several hundred/thousand hours.
Honestly, I do not know how to train someone to fly, so I couldn't answer
this with certainty (perhaps someday), but the problem with teaching a
primary student to NEVER take off in a tailwind scenario without explaining
the actual thought process behind the takeoff/landing runway decision is to
severely limit the student. I hope I have given you at least a few real
life reasons one may have to takeoff with a tailwind.
> When I first started simming (almost 6 years ago now!)
> I read in the manuals that a certain amount of lift was necessary to get an
> aircraft airborne. One can achieve this lift by taking off against the wind
> (i.e. face first).
>
> Taking off with a tail wind would give the aircraft a little extra speed,
> but wouldn't it also force it more downward than upward?
No. Again, discounting gusts for this discussion (which can cause a type
of windshear and can momentarily affect lift), a tailwind affects
groundspeed, not relative wind across the airfoil. Thus, the aircraft's
movement across the ground will be faster at the point where relative wind
across the airfoil indicates proper rotation speed.
The faster groundspeed results in more runway used up and this can be the
danger in taking off with a tailwind (considering short runways with
obstacles at the end). Lift is not affected.
--
Peter
----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups
----= East and West-Coast Server Farms - Total Privacy via Encryption =----