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Old August 19th 03, 02:55 AM
Roy Smith
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"Chip Jones" wrote:
Here's the deal.


An interesting choice of words :-)

In the most professionally bored voice I can muster, I key up and say "Baron
123, traffic alert, traffic two o'clock, two miles converging from the right
indicating 7000, suggest you turn right heading 180 immediately."
[...]
Given this traffic scenario, would any of you guys have followed my
suggestion to turn to a 180 heading, or was I wasting my breath?


Hard to say for sure, but I can offer a few insights from my own
experiences. As a general rule, if the controller says, "immediately",
I put my life in his hands, follow orders, and ask questions later.

I've only once heard the phrase "traffic alert". I was IFR, the
controller was not talking to the other guy. It was not solid IMC, but
there was plenty of IMC around. I can only guess the other guy was not
legal VFR.

In this case, the controller did not issue a suggested heading. My
response was to turn 90 degrees away from the direction the traffic was
being called. I can certainly see your point where turning directly
into the traffic would have put me behind him, but that wasn't my
instinctive reaction.

I suspect your traffic call may have been by the book, but on the other
hand, it was probably too verbose to really be useful to the pilot. I'm
guessing that with each successive traffic call leading up to the alert,
the pilot was getting increasingly antsy about the unseen traffic, and
already working out an escape plan -- "bad stuff to the right, I gotta
get left, away from the danger". All it took was hearing the words
"traffic alert" to trigger that plan into action.

I just timed how long it took me to calmly read the above clearance.
Seven seconds between "traffic alert" and "heading 180". At standard
rate, the guy's already 20 degrees into his left turn before he knows
you want him to turn right (and I'm not sure I would limit myself to
standard rate in response to a traffic alert). More than the physics of
changing heading, consider the human factors -- he's already made a
decision and acted on it. He's already made the mental leap from
obeying instructions to acting on his own. It's not going to be easy to
get him back into the fold quickly.

My guess is, by-the-book or not, a better way to say it might have been,
"Barron 123, traffic alert, immediate left turn, heading 180". Get it
right up front what you want the guy to do.

I fully understand the reason the book wants the phrasing the way it
does. It's the PIC's decision, and the controller is just feeding the
PIC information which will let the PIC make an informed decision. The
problem is, I don't think it works that way in real life. It's hard
enough working CPA problems (Closest Point of Approach; do they call it
that in the ATC world?) looking at a screen or a plotting sheet. It's
damn near impossible in your head with nothing better than an O'Clock
traffic call, some dubious WCA, an unknown speed and cardinal heading on
the target, and no formal training.

PIC-correctness, legality, and liability issues aside, the fact is the
controller is the one with the best picture of what's going on, and it
makes the most sense for the controller to take charge and issue an
unambigious instruction, with no extraneous information to get in the
way of communicating the one thing you really want to communicate: which
way to turn.

It's a pity there's no mechanism to plan stuff like this a little
further in advance. At the 5-mile point, it would be nice if I could
hear, "Hold current heading for now. If you don't see him in another 3
miles, I'm going to turn you left to pass behind him". Does "the book"
allow for such a conversation?

My other hobby is racing sailboats. A very important part of the sport
is judging crossing situations. I'm here, you're there. I'm on this
heading and speed, you're on that heading and speed. Will I cross in
front of you? Will you cross in front of me? There's often a big
tactical advantage to me crossing in front (as opposed to changing
heading to make sure I cross behind), so there's a lot of incentive to
learn how to judge these things closely.

You don't want a surprise. If we're not sure of the crossing situation,
we want to have a plan as far in the future as we can as to what we'll
do if it gets to the decision point and it's still not clear we can make
it across the other guy's bow. That way, when the time comes, I don't
have to explain what Plan-B is, we just have to tell the crew that
Plan-B is what we're doing.

Think about what was going on from the pilot's perspective. You kept
telling him, "Something bad might be happening soon. I know the best
way to deal with it, but I won't tell you what it is yet. Don't worry,
though, at the last possible second I'll clue you in on the plan and
then expect you to react immediately".

Well, anyway, that's my take on it. Other people will probably have
different opinions.
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