Looking for a math wiz!

Chad Speer wrote:
This tool is basically meant to be a replay of a high altitude training
session, where the trainer can say "Okay, let's see what would have
happened if you had turned AAL460 fifteen left rather than descending
him." As it exists now, it is really cool, but a bit unrealistic. If
the winds are strong enough, a fifteen degree turn can easily add
twenty knots to a groundspeed. [..]

Chad, I think we need to stop and get the requirements, so we can help
better. I'm guessing how the program will work:

You have data from a training session. It has a recording of many
aircraft movements that you can play back. Perhaps you add one new
and controllable craft to the mix (AAL460 above?) and that's the one
that gets vectored by the trainee, to see what kind of trouble he can
get in/out of. Since all the other aircraft had been affected by wind,
the controllable plane needs the same flight input. Is this a good
description?

If so, I'm thinking that the wind within the 2000' block you talked
about, is a single fixed value for the entire training session. Would
that be fair to say? If that is true, then you don't need to
calculate the wind except once at the beginning. Can this be stored
for later use each time?

Just trying to get a handle on things,
Kev

Kev wrote:
*****
You have data from a training session. It has a recording of many
aircraft movements that you can play back. Perhaps you add one new
and controllable craft to the mix (AAL460 above?) and that's the one
that gets vectored by the trainee, to see what kind of trouble he can
get in/out of. Since all the other aircraft had been affected by wind,
the controllable plane needs the same flight input. Is this a good
description?

If so, I'm thinking that the wind within the 2000' block you talked
about, is a single fixed value for the entire training session. Would
that be fair to say? If that is true, then you don't need to
calculate the wind except once at the beginning. Can this be stored
for later use each time?
*****

Hey, Kev. We're not going to be adding tracks, we'll just review what
was done with the existing aircraft. The real kicker is that the
operator can effectively take control an aircraft and "fly" it
according to an alternate set of instructions the controller could have
given the pilot. We can then watch the original track of the aircraft
alongside the simulated track and see how the situation would have
developed if the controller had made a different choice.

The playback has no idea what the winds are. If we don't account for
the winds, the simulated track for an aircraft would behave as though
the wind was calm, which is highly unrealistic. Since this is a short
time frame and a relatively small chunk of airspace, a single
calculation for winds would be fine.


Chad Speer
PP-ASEL, IA
ATCS, Kansas City ARTCC

Chad Speer wrote:
Hey, Kev. We're not going to be adding tracks, we'll just review what
was done with the existing aircraft. The real kicker is that the
operator can effectively take control an aircraft and "fly" it [...]

The playback has no idea what the winds are. If we don't account for
the winds, the simulated track for an aircraft would behave as though
the wind was calm, which is highly unrealistic. Since this is a short
time frame and a relatively small chunk of airspace, a single
calculation for winds would be fine.

Okay then. This is like my earliest days of programming back with 4K
memory and a slow cpu :-) Sometimes the simplest ways are best.

I think someone else noted that since you know the filed TAS and the
radar-derived GS, then the Headwind values will be super easy to
derive. (TAS-GS)

So what I would do is try to find aircraft facing the four or eight
main compass directions. Calculate and store the head or tail wind for
each base direction in a lookup array. Extrapolate if wished for more
compass points. You can do this once at the beginning, or do it at
various intervals if more aircraft will turn and give finer data.

Now just apply that simple wind info (by array lookup of the rough
course) to the TAS of the plane you are taking control of. It should
be quite sufficient since you really just need the basic wind effect on
its TAS as it turns... the crosswinds and airplane headings don't
matter in your case.

Regards, Kev

Kev wrote:
*****
I think someone else noted that since you know the filed TAS and the
radar-derived GS, then the Headwind values will be super easy to
derive. (TAS-GS)
*****

This is interesting. I hadn't considered breaking them up into
headwind and crosswind components. I see the simplicity in that, but
I'll have to run that through the brain a few times to see how it fits.
I certainly can't dismiss it offhand!


Chad Speer
PP-ASEL, IA
ATCS, Kansas City ARTCC

Chad Speer wrote:
This is interesting. I hadn't considered breaking them up into
headwind and crosswind components. I see the simplicity in that, but
I'll have to run that through the brain a few times to see how it fits.
I certainly can't dismiss it offhand!

No crosswind calcs needed. No trigonometry needed. Just addition and
subtraction.

In your case, aircraft always follow a specified course. Headings
don't matter. Crosswinds don't matter. The only thing that changes is
their speed, and that's simply TAS +/- wind speed for a particular
direction.

So if you calculate at startup the head/tail wind (TAS-GS) for two
aircraft flying basically North or South, and East or West, then you
have enough rough information to extrapolate the speed of the trainee's
airliner, as it turns to face different directions. It's not precise,
but it's good enough to make things more realistic by at least having
the speed change appropriately for each direction.

Kev