Part II of The ANN Interview With Avidyne's Dan
By ANN Senior Correspondent Kevin R.G. "Hognose" O'Brien
Aero-News: Can you give me an example of
something, a way they used it (surprising uses of Avidyne's
Dan Schwinn: I'll give you -- which one?
Aero-News: Well, we'll come back to when they
were doing things that were more difficult than they need to be,
because I do want to talk about training on these sophisticated
systems. But talk about something they're doing, that's something
you didn't expect. Did these guys teach you a capability of your
system that you didn't know about, in a way?
Dan Schwinn: Well, one of the big debates
around datalink weather has been on the tactical versus strategic
use of datalink. Tactical
meaning: ten degrees to the right, ten degrees to the left, have to
go around this little spot, take a left around this little spot,
take a right around that one. Strategic meaning, line of storms is
here, I'll go over it and I'll miss the whole thing.
Aero-News: Almost, a preflight planning versus
inflight planning use of it?
Dan Schwinn: It might be in flight, but... in
the example that we had last week, we were coming back from Canada.
I was sitting in the back.
We had a bunch of guys, two pilots sitting in the back, two in the
front. That's like three more pilots than you really need to have
on board. (Dan begins sketching on a whiteboard).
Aero-News: Yeah, a bunch of people fidgeting on
Dan Schwinn: Yeah. So, it's normal northeast
conditions -- you remember, when we had that bad weather last
Wednesday and Thursday. So, we're going from here, Canada, down to
Bedford. And there's a line of storms in between.
Now, strategically, by looking at this, you could have done
either the down and around here (pointing to the southwest end of
the storm line), but this went down pretty far south. You could
have done the up and around here (pointing to the NE terminus of
the storm line). Both valid.
And, of course, this stuff is all moving. And either of these
routes is probably fifty percent more mileage. So instead what we
do -- and I'm just sitting in the back, kind of enjoying the show
-- is, we go right at this (points at a possible fault line in the
line of storms), we come over here, tack back like this. (Indicates
a zigzag path through the storm line).
The narrowest gap here, between the greens, is maybe half a
mile. And we're up over Vermont, or someplace like that. Now, the
datalink has two kilometer, one mile resolution on the XM. And
there's slant angle, and there's "where is the precipitation really
currently" -- we're flying around 8,000, or something like
And these guys are going, "We're going to navigate right through
this, and there's not going to be anything there, because, look, it
says so on the datalink."
And it was true! But it's not definite that it's going to be the
Aero-News: It's a probabilistic thing that
there's not going to be anything there, perhaps.
Dan Schwinn: Right. Now as we're doing this, there's a big blob
of red [most serious activity] here. ANd we're trying to get here
as fast as possible. And the question is, do I go way out away from
this thing -- do I leave it ten miles? -- or do I slice right by
it? And the answer is, if there's convective [activity] in there,
you stay ten miles away.
but if there isn't? Go right by it. It's just a bunch of heavy
And that's where the lightning reporting comes in.
Aero-News: It's all which stage of a
thunderstorm you're in.
Dan Schwinn: Well, if there's [even] one there.
maybe it's just heavy rain. So, in this case, we saw a few little
guys down here [lightning strikes far from the precipitation and
the planned flight path] and nothing up here [near the flight
path]. So we went a little bit closer to it and the ride was
perfectly smooth. The whole way, a perfect ride.
It was a textbook demonstration of what you can do with datalink
that you could never do without it. You would have been vectored
None of this stuff [pointing at the cells that were zigged and
zagged around] was going to kill you, either, but you could have
had a miserable ride.
Aero-News: And the other thing is, you could
have been in the air for half again as long.
Dan Schwinn: And you could have been a lot more
worried about it! I mean, we're just cruising along having a ball.
It's all there -- you know exactly -- you've got total knowledge.
You talk to ATC, you're not asking them, you're saying, "well, we
want to deviate 20 degrees right for 30 miles and then we're gonna
cut back to the northeast for about 10 miles and then we're gonna
head directly to destination, is that OK?" [Puts on ATC voice]:
"Sure, sounds like you guys know what you're doing."
You know, they don't care, as long as you're not in a heavy
Aero-News: So when you're conceiving this
integration of systems, you never imagined that people would do
these things with it?
Dan Schwinn: You know, you kind of imagine it
but you don't really know what's going to happen. And the thing
that I found particularly interesting in listening to the
discussion between the two guys who were flying -- remember there
were four of us pilots, two guys flying and two guys with color
commentary in the back -- and I'm sitting there and they're saying,
"yup, we're going to be able to go right around it like this and
like that," -- and I'm sitting there going, "What do you guys think
the accuracy of those green and yellow areas is?"
"Well, it's up there on the screen, it must be exactly
"Well, what age do you think it is?" and the guy looks up on the
thing, and there's a little number, and he says, 'Well, it's three
But that three minutes is three minutes from when it was
composited, which is not necessarily from when the raindrop was
formed. It's not much longer than that, but it's just kind of funny
to listen to people.
"It's on the screen so it must be exactly correct."
Aero-News: Also, it's possible that -- you know
a great deal about what feeds into the system. You have all these
different radars on the ground, that are going together, it's all
being composited into one picture. And every one is on its own
And depending on how far away you are from the radar, you're at a
different slant angle, and a different slant angle with a different
Aero-News: Same issue you have with DME or
anything that's a line of sight radio signal.
Dan Schwinn: But the point is that -- and this
is one that nobody realizes -- you're flying along at 3,000 feet
and you look at your screen and your radar's perfectly clear, and
then you fly into a rain squall -- "What happened?!" Well, you're
150 miles from the radar, and it can't see anything -- this
whole rainstorm is only 8,000 feet tall.
And the radar's shooting right over the top of it.
Aero-News: Because of the curvature of the
Dan Schwinn: Nobody thinks of that.
Aero-News: Now, is that something -- is it
possible that we're going to give pilots overconfidence because
they see, "The red ends here and the green ends here, and that's
the way it is."
Dan Schwinn: But here's the thing. Are you
going to fly through a red rainstorm that's 7.000 feet tall? Are
you gonna get hurt? You're gonna get wet, you're not gonna get
hurt. The only thing that's really going to hurt you is if there's
I mean, all this stuff -- you can separate this weather business
into two things. Or maybe three. One is whether you get wet, two is
whether you have a rough ride, and three is whether you actually
enter convective weather.
The third one --
Aero-News: That's the one that breaks airplanes
and kills people.
Dan Schwinn: -- is the one that breaks
airplanes. And all of these systems can help you avoid that. A few
lightning specks... the red... but in fact, they're giving you
indications. They're giving you false positives of convective.
It could be heavy rain or it could actually be convection.
There's no way to tell the difference on an onboard radar or
Aero-News: You can't see air movement with
Dan Schwinn: That's where the 'sferics are kind
It's an evolving area.
To Be Continued...