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Riddle me this, pilots

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Old August 19th 03, 01:21 PM
Roy Smith
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In article ,
(blanche cohen) wrote:

Um....Bob & Chip...could you explain in more detail the reason
for the "turn into traffic"? I'm having problems visualizing
it. And I have the most horrible feeling that someday I'll run
in the same problem and want to understand it.


That one's easy.

Let's say you've got two objects moving in space (doesn't matter if
they're airplanes, boats, or cars). They are on intercept courses,
something like this:



Assume for the moment you're object #2, trying to decide how to avoid
hitting #1. Assume that #1 is going to keep moving at a constant speed
and direction. Further assume that the problem is reduced to 2D (i.e.
nobody can change altitude).

You've basicly got 4 choices: you can speed up, slow down, turn left, or
turn right. In boats or planes, speed changes usually happen pretty
slowly, so they're really not effective for short-term collision
avoidance. This leaves you with turn left or turn right.

Let's say I make an 45 degree turn to the right (away from the target).
Now the situation is this:



Quick, is this an intercept situation? Can you work out in your head if
#2 will cross in front of #1? They're still moving towards each other,
so it's hard to tell.

But, what if #2 turned to the left, toward the target? Now you've got:



It should be obvious in the picture above that #2 is going to pass
behind #1. Look at the arrow heads (the lengths of the arrows are how
far each target will move in, say, 1 minute). By the time #2 gets to
the head of its arrow, #1 has already moved from it left side to its
right side.

The basic rule is that if you're aiming right at a crossing target,
you'll never hit it, because while you're moving towards it, it's moving
cross-wise to you and will move away from where you're aiming. The
correlary of this is that if you *want* to hit the target, you need to
lead it (this is the "firing solution" stuff they're always doing in
submarine movies when they launch a torpedo).
Old August 19th 03, 01:51 PM
Leland Vandervort
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On Tue, 19 Aug 2003 11:44:03 GMT, "Gary L. Drescher"

"Chip Jones" wrote in message
This kind of turn can be be counter intuitive to the pilots involved.

Yup. It was to me until I gave it more thought.

Actually, to me it seems quite logical and would have been my initial
reflect to turn TOWARDS the conflicting traffic, since the whole
purpose of the exercise would be to change the constant bearing of
closure.. turning away from it will only slow the rate of bearing, not
necessary change the angle (as viewed from overhead both, not as in
"clock" positions from the pilot's perspective).. turning towards it
will increase the rate briefly until the vector angle is depassed and
then it will widen again. Of course if the other traffic does the
same thing, then you're going from a constant relative 90 degree
closing bearing to a constant relative head-on closing bearing which
will also be a bad thing... of course in this particular case the
other [unidentified] aircraft was seen to maintain his course.


Old August 19th 03, 02:49 PM
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"Capt. Doug" wrote in message ...
Chip Jones wrote in message The response I get is "Baron 123 is IMC, no


While your scenario may be right on the money, let me point out that some
pilots will claim to be IMC even when there isn't a cloud in the sky. Their
reasoning is that by doing this, it keep the onus of seperation on the

Hi Doug,

There's also the vis. factor. If it's hazy and you're flying towards
the sun, you can't see a durn thing even if there isn't a cloud out
there. You're flying on instruments; isn't that properly described
as "IMC" with no funky legal reasoning behind it?

OTOH, a plane flying perp. or away from the sun can legitimately
see 3+ miles

IIRC the Baron was flying 110, early a.m., perhaps this is possible?

Old August 19th 03, 03:08 PM
Stan Gosnell
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"Chip Jones" wrote in

The only problem about issuing the 180 heading as an instruction
instead of a suggestion is that I do not have separation
responsibility between an IFR and a VFR in this class of airspace.
Because of that, I have to follow the 7110.65's provisions regarding
safety alerts and traffic alerts, and the 7110.65 requires me to make
a suggestion instead of taking control with an instruction in this
case. In fact, the 7110.65 even instructs me to use the phraseolgy
"immediately" if I offer a suggested course of action. Hence, if your
best course of action was to hold your present heading, and I
suggested this to you, I would actually have to key up and say
something as ridiculous as "N123, traffic alert [insert appropriate
information here], suggest you fly your present heading immediately
for traffic!" Silly, ain't it?

Any similarity between logic and government regulations is purely
coincidental and completely unintended. But if you ever see me heading for
another aircraft, please point me somewhere else, whatever phraseology you
can come up with that will satisfy 7110.65. If we have a midair, you'll be
down there blameless in the FAA's eyes, but I'll come back and haunt you.



Old August 19th 03, 03:56 PM
Ron Natalie
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"Snowbird" wrote in message om...
Jesu! I hate pilots who fly illegal IMC. Making the most charitable
interpretation possible, it's possible that the Baron was in spotty
IMC and the other pilot climbing through a hole, and that his Mode C
was off.

Or the visibility was right at three miles and the sun was in the Baron
pilot's eyes, etc...

Old August 19th 03, 04:36 PM
Chip Jones
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"Dr. Anthony J. Lomenzo" wrote in message

Note to Chip! Chip, your name rings a bell...didn't you have a rather
elaborate ATC website { I could have the wrong person but your sector
mention after your name [ZTL] rings a bell ... as well as a secondary
website dealing with flight safety [read: crash] investigation issues?

Not me. :-)

Chip, ZTL

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