to HSI or not to HSI

Please excuse the hijacking of this religious/political forum to raise a
question about flying.

My partners and I are faced with a decision. What would you do?

We plan to update our outdated panel with a GNS480. The CDIs currently installed
are not compatible with the GNS480, so one of them will be replaced.

We could replace the existing CDI with a compatible one for $2000.

We could install a non-slaved NSD360 HSI instead for $3500.

If we install the HSI, the no-longer-used CDI hole can be used for the electric
AI that's been waaaay over on the other side of the panel.

I think I know what we will do (go for the HSI), but I'm collecting opinions.

Is the NSD360 likely to become a maintenance headache?

In the electronic age, does it make sense to install an electromechanical aid to
situational awareness?

Thanks,

Dave

This was heatedly discussed in the Cessna owners' group a
few months back. People seem to be completely polarised
about it. FWIW, I love my HSI and would hate to have to
fly without it. It was one of my key decision factors in
choosing a plane to buy. It just makes things SO much
easier as compared to a DI and a separate CDI. I've
flown a couple of times behind a Sandel electronic HSI
and that was even better, although I wouldn't pay
$10K to upgrade.

John

Dave Butler wrote:
Please excuse the hijacking of this religious/political forum to raise a
question about flying.

My partners and I are faced with a decision. What would you do?

We plan to update our outdated panel with a GNS480. The CDIs currently
installed are not compatible with the GNS480, so one of them will be
replaced.

We could replace the existing CDI with a compatible one for $2000.

We could install a non-slaved NSD360 HSI instead for $3500.

If we install the HSI, the no-longer-used CDI hole can be used for the
electric AI that's been waaaay over on the other side of the panel.

I think I know what we will do (go for the HSI), but I'm collecting
opinions.

Is the NSD360 likely to become a maintenance headache?

In the electronic age, does it make sense to install an
electromechanical aid to situational awareness?

Thanks,

Dave

jharper aaatttt cisco dddooottt com opined

This was heatedly discussed in the Cessna owners' group a
few months back. People seem to be completely polarised
about it. FWIW, I love my HSI and would hate to have to
fly without it. It was one of my key decision factors in
choosing a plane to buy. It just makes things SO much
easier as compared to a DI and a separate CDI. I've
flown a couple of times behind a Sandel electronic HSI
and that was even better, although I wouldn't pay
$10K to upgrade.

I love my HSI! But it might be better to wait and save for a glass panel.

Should the best be the enemy of the the good?

Dave Butler wrote:
Please excuse the hijacking of this religious/political forum to raise a
question about flying.

My partners and I are faced with a decision. What would you do?

We plan to update our outdated panel with a GNS480. The CDIs currently
installed are not compatible with the GNS480, so one of them will be
replaced.

We could replace the existing CDI with a compatible one for $2000.

We could install a non-slaved NSD360 HSI instead for $3500.

If we install the HSI, the no-longer-used CDI hole can be used for the
electric AI that's been waaaay over on the other side of the panel.

I think I know what we will do (go for the HSI), but I'm collecting
opinions.

Is the NSD360 likely to become a maintenance headache?

In the electronic age, does it make sense to install an
electromechanical aid to situational awareness?

Thanks,

Dave




-ash
Cthulhu in 2005!
Why wait for nature?

"Dave Butler" wrote in message
...
Please excuse the hijacking of this religious/political forum to raise a
question about flying.

My partners and I are faced with a decision. What would you do?

We plan to update our outdated panel with a GNS480. The CDIs currently
installed are not compatible with the GNS480, so one of them will be
replaced.

We could replace the existing CDI with a compatible one for $2000.

We could install a non-slaved NSD360 HSI instead for $3500.

If we install the HSI, the no-longer-used CDI hole can be used for the
electric AI that's been waaaay over on the other side of the panel.

I think I know what we will do (go for the HSI), but I'm collecting
opinions.

Is the NSD360 likely to become a maintenance headache?

In the electronic age, does it make sense to install an electromechanical
aid to situational awareness?

Thanks,

Dave

Great question! Although I can't imagine flying without an HSI (all my
flying since my private checkride has been behind an HSI), it seems that
there will be a breakthrough soon. With some experemental PFDs selling for
under $2000 with AHARS, it seems that someone must be cooking up a
self-contained EHSI with internal gyro. I don't actually know of anyone
working on this but it seems unlikely that it is not being persued

Mike
MU-2

"Mike Rapoport" wrote in message
k.net...


under $2000 with AHARS, it seems that someone must be cooking up a
self-contained EHSI with internal gyro. I don't actually know of anyone
working on this but it seems unlikely that it is not being persued

It already exists, i.e. Garmin 195 or anything later.

(Yes, I know, it is not based on a gyro, has a somewhat slower response
time, and is not legal for primary navigational or attitude information.
Nonetheless, it works quite well to supplement a panel DG.)


--------------------
Richard Kaplan, CFII

www.flyimc.com

Dave Butler wrote
If we install the HSI, the no-longer-used CDI hole can be used for the electric
AI that's been waaaay over on the other side of the panel.

Actually, if your primary AI is vacuum and the secondary is electric,
you can simply remove the T&B and install the second AI in its place.
AC91-75 permits the replacement of the T&B with a second AI, as long
as the power source for the 2nd AI is different from the power source
for the 1st AI. So really, being able to free up the hole should not
factor into your decision.

Some people love HSI's, some hate them, some are indifferent. I've
flown several planes with HSI's and I'm indifferent. It's OK. A DG
with CDI is also OK. About the only time an HSI really has an
advantage is when you're flying reverse course on a localizer. Other
than in training, I do not believe I have ever had to do that.

Michael

"Michael" wrote in message
om...
Dave Butler wrote
If we install the HSI, the no-longer-used CDI hole can be used for the
electric
AI that's been waaaay over on the other side of the panel.

Actually, if your primary AI is vacuum and the secondary is electric,
you can simply remove the T&B and install the second AI in its place.
AC91-75 permits the replacement of the T&B with a second AI, as long
as the power source for the 2nd AI is different from the power source
for the 1st AI. So really, being able to free up the hole should not
factor into your decision.

Some people love HSI's, some hate them, some are indifferent. I've
flown several planes with HSI's and I'm indifferent. It's OK. A DG
with CDI is also OK. About the only time an HSI really has an
advantage is when you're flying reverse course on a localizer. Other
than in training, I do not believe I have ever had to do that.

Can you explain why that is the one advantage (BC)/revers on localizer, and
why that is so?
Do you mean to say that people confuse which color sector they are in on a
localizer due to "reverse needle"? If so then it is a training issue, not a
technology issue.


Michael

In article ,
Richard Hertz no one@no one.com wrote:
Can you explain why that is the one advantage (BC)/revers on localizer, and
why that is so?

An HSI is like a CDI you can spin around. When shooting a back course
it is effectively upside down, cancelling out the reverse sensing.

--
Ben Jackson

http://www.ben.com/

"Ben Jackson" wrote in message
news:mkXkd.397609$D%.109302@attbi_s51...
In article ,
Richard Hertz no one@no one.com wrote:
Can you explain why that is the one advantage (BC)/revers on localizer,
and
why that is so?

An HSI is like a CDI you can spin around. When shooting a back course
it is effectively upside down, cancelling out the reverse sensing.

Yes, thanks.
But there is no such thing as "reverse-sensing" on the localizer. If
perhaps the current common teaching of localizers and CDI was corrected then
we that selling point of HSI is dropped.

The CDI needle points to the color sector you are in. On some (older) nav
heads the blue and yellow sectors were indicated. So, no need to look for
reverse sensing/etc, just look at the approach chart, look at the needle and
you will know where you are relative to the course. Nothing could be
simpler.


--
Ben Jackson

http://www.ben.com/

"Richard Hertz" no one@no one.com wrote
Can you explain why that is the one advantage (BC)/revers on localizer, and
why that is so?
Do you mean to say that people confuse which color sector they are in on a
localizer due to "reverse needle"?

Yes, that is exactly what I mean to say.

If so then it is a training issue, not a
technology issue.

Oh man, here we go. You've just touched off a religious debate.

In real life, I run a department that designs instrumentation for
process environments. What that means is that engineers design it,
but generally non-engineers (plant operators, meter readers,
technicians) install and use it. These days, most instrumentation has
software in it, so it should not come as a surprise that I rose into
that position from software engineering.

In the process, I learned a lot about user interfaces. There are two
kinds of user interface bug. There is the kind where the user
interface acts contrary to design, in a useless or unpredictable
manner in a given situation (coding error) and there is the kind where
it acts as designed (intentionally or unintentionally), in a manner
that is predictable and useful but, in certain situations,
counter-intuitive to the operator (design error). The first kind is
unusuable in those given situations. The second kind is usable,
provided you read the manual and are aware of how the system will
behave. There are those who believe that this means it's not an error
- that you should simply RTFM. In other words, that it is a training
issue. They are wrong.

The "reverse" indication of a conventional CDI is a design error. You
can work around it. I have. I had to shoot a LOC BC approach with
engine failure at leveloff (simulating a failure of the engine to come
up on the powerup for leveloff) followed by a single engine missed
approach. I passed - meaning I executed the approach and miss to ATP
standards, and I have the certificate to prove it. Nonetheless, a
couple of times I found myself, with the needle half a dot off,
applying the incorrect contol inputs before I "caught" myself. So
clearly the training worked - I corrected before I deviated beyond ATP
standards - but that doesn't mean that the design is correct. It's
not. On an approach, you're used to correcting towards the needle.
Under normal conditions, you should have the situational awareness to
know what you are doing, rather than just correcting by habit.
However, in emergency conditions where the workload becomes high,
there is a tendency to revert to habit. In other words, the operation
becomes counter-intuitive.

Sometimes this is unavoidable, but where this is done for no good
reason, it's simply bad design. It's really quite simple to modify a
conventional CDI for "reverse" sensing - all it takes is the addition
of a simple DPDT switch, and the needle will act correctly on the BC.
Thus I have to say it's done for no good reason. Only in aviation is
somehting like this not done - because this is how we've always done
it (and because the FAA would make such a modification
cost-prohibitive).

The UK (and I believe other nations) will not certify LOC-BC
approaches because the potential for error is believed to be too high.
I don't agree with this - I consider the potential for error to be
adequately low with proper training - but the addition of a cheap,
simple, and reliable part to the CDI (or replacement with an HSI)
eliminates the potential for error - and is thus clearly an advantage.

Michael