Altitude Call Out is COOL

Jay Honeck wrote:
I did a flight shortly after getting the 396 installed. I had the
altitude voice on, and had a multi-leg route programmed into it as the
active flight. I decided to land at an intermediate airport that wasn't
at the end of the flight plan. The voice came on during final approach
with terrain warnings and demands to "pull up". Thought it was rather
amusing but it is probably a good feature to have.

That's a neat feature -- although I'm glad you told me about it
*before* it surprised me.

Can you imagine flying a newbie somewhere for lunch, diverting to a
different, nearby airport, and having THAT come over the intercom
turning base to final?

Hi Jay,

You can get the same warning even at the destination airport. I talked
to a Garmin engineer who explained how they decide whether you are
landing or just too close to terrain.

At the destination airport, there is a virtual surface that is lower
along the axis of the *primary* runway at the airport. If you break that
surface, you get the warning. Landing on some runway other than the
primary runway, the virtual surface is higher and you are more likely to
get the warning.

For example, I get it all the time when landing on runway 32 at RDU
(Raleigh/Durham, NC). The primary runways at RDU are 05/23 L and R.

There seem to be some other anomalies where you can get the warning. I
used to get it all the time when turning final for runway 21 at TTA
(Sanford, NC). I never could find anything unusual about the terrain or
obstructions there. I think another r.a.o poster also mentioned this
anomaly. Come to think of it, I just did that landing the other day, and
didn't get the warning, so maybe they've changed something in the later
versions of the firmware.

I try to remember to warn my Angel Flight passengers that they might
hear the warning. It's quite alarming if you're not prepared for it.

Dave

You can get the same warning even at the destination airport.
..stuff snipped
There seem to be some other anomalies where you can get the warning. I
used to get it all the time when turning final for runway 21 at TTA
(Sanford, NC). I never could find anything unusual about the terrain or
obstructions there. I think another r.a.o poster also mentioned this
anomaly. Come to think of it, I just did that landing the other day, and
didn't get the warning, so maybe they've changed something in the later
versions of the firmware.

I get the "pull up" terrain warning on my 396 when turning base at too
high a sink rate. We have towers nearby and my theoretical flight path
would put me too close to them if I did not turn final. Somehow I am
outside the zone of "landing" at that point. With the aerodynamics of a
2 by 4, I come in a wee bit higher than some expect (Cherokee 140 -
nuff' said). I finally see "red over white" on short final. Maybe that
does it. It seems to be coupled to the sink rate cuz I sometimes get it
on final.

Mike

Mike Spera wrote:
With the aerodynamics of a
2 by 4, I come in a wee bit higher than some expect (Cherokee 140 -
nuff' said). I finally see "red over white" on short final.

Is that because you're doing power-off landings? I fly a Warrior, which I
assume has simular aerodynamics, and have no problem holding the
glideslope. With power in, you'd be able to control the descent rate, no?

.... Alan
--
Alan Gerber
PP-ASEL
gerber AT panix DOT com

With the aerodynamics of a
2 by 4, I come in a wee bit higher than some expect (Cherokee 140 -
nuff' said). I finally see "red over white" on short final.

Is that because you're doing power-off landings? I fly a Warrior, which I
assume has simular aerodynamics, and have no problem holding the
glideslope. With power in, you'd be able to control the descent rate, no?

That's the way I do it, too (and I think most Cherokee pilots carry a
bit of power to land smoothly) -- but a lot of guys like to do
power-off landings, just to prepare themselves for the eventuality of a
failed engine in the pattern.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

Alan Gerber wrote:
Mike Spera wrote:

With the aerodynamics of a
2 by 4, I come in a wee bit higher than some expect (Cherokee 140 -
nuff' said). I finally see "red over white" on short final.


Is that because you're doing power-off landings? I fly a Warrior, which I
assume has simular aerodynamics, and have no problem holding the
glideslope. With power in, you'd be able to control the descent rate, no?

... Alan


No, No, No, my friend. The tapered wing is WAY different than a constant
chord wing. Power is at around 17500 rpm and it sinks like a rock. Go
for a ride in a 140 and you will be enlightened (or scared to death).

Yes, you can control the descent rate right at 500fpm. But, you do so at
a MUCH greater angle to the ground than your Warrior. First time I flew
a tapered wing I could not believe how flat you had to come in to avoid
floating right past the airport. If you tried that with the 140, your
CFI would immediately pull the power back and announce "Engine Out" and
laugh while you quickly figured out you would NEVER make the runway.

Try it out.
Mike