Why don't voice radio communications use FM?

In article ,
Dylan Smith wrote:

I've seen general aviation displays that run Windows NT. They don't have
the Win32 subsystem (which is what really sullies the NT based operating
systems, the actual NT kernel that lies beneath things like the win32
subsystem is quite small and elegant).

Do any of those displays have the software at DO-178B Level C or higher?
(btw - I do know a little about the avidyne display)

--
Bob Noel
Looking for a sig the
lawyers will hate

"Mxsmanic" wrote in message
...
Thomas Borchert writes:

So I guess you can point to the accidents caused by Windows-based glass
cockpits as well as you pointed to sources for accidents caused by AM
radios?

Not yet.

As far as I know (and hope), these cockpits don't have any trace of
Windows running in them. If they do, the situation is much more dire
than I had feared.

You neeed to look a litle closer.

"Mxsmanic" wrote in message
...
Dave Stadt writes:

Nope, it was quite a ways down the line. Morse code via spark gap
transmitters was one of the first.

All early audio used AM.

Yea, so.

Thomas Borchert wrote:
Mxsmanic,

It's hard to put a price on safety.


You are making the second step after the first. You still haven't shown
how the use of AM radios influences safety. If there is no connection
between AM and safety (and you have shown zero evidence that there is,
even when asked to show it), then it can't possibly enhance safety. So
we're really discussing the price of radios, not of safety.

And actually, the FAA and NTSB DO put a price on safety.

But why introduce logic at this point?

Dylan,

accidents caused by bad radio communications are so rare, they
barely register as statistical noise!


Ah, but if it weren't for AM, that noise would be so much less ;-)

--
Thomas Borchert (EDDH)

On Mon, 04 Sep 2006 08:41:34 -0400, Bob Noel
wrote in
:

Do any of those displays have the software at DO-178B Level C or higher?
(btw - I do know a little about the avidyne display)

I am very apprehensive about Avidyne avionics. What can you say about
their products?

In article ,
Larry Dighera wrote:

Do any of those displays have the software at DO-178B Level C or higher?
(btw - I do know a little about the avidyne display)

I am very apprehensive about Avidyne avionics. What can you say about
their products?

I don't have any in my 140, but then, I don't even have any GPS whatsoever.
This is more a reflection of not needing to upgrade a good 1995 panel than
a reflection on Avidyne.

I can say that Avidyne was the first company to get a windows-based product
certified to a 178B level that would ordinarily be level C. Note that the
windows portion of the software does NOT comply with Level C objectives.
But last I knew, Avidyne consider the technique(s) used to be proprietary.
(I don't what they are, but I have some educated guesses on possible methods).

I've seen some demos of their products, which look way cool, but they are
also way too expensive for me.

Not much help - I know...

--
Bob Noel
Looking for a sig the
lawyers will hate

On Mon, 04 Sep 2006 11:29:17 -0400, Bob Noel
wrote in
:

In article ,
Larry Dighera wrote:

Do any of those displays have the software at DO-178B Level C or higher?
(btw - I do know a little about the avidyne display)

I am very apprehensive about Avidyne avionics. What can you say about
their products?


I can say that Avidyne was the first company to get a windows-based product
certified to a 178B level that would ordinarily be level C.

Just so we are all aware of the definition of DO-178B software levels:

http://en.wikipedia.org/wiki/DO-178B
Software level
-------------

The required level is determined from the safety assessment
process and hazard analysis by examining the effects of a failure
condition in the system. The failure conditions are categorized by
their effects on the aircraft, crew, and passengers.

Catastrophic [Level A] - Failure may cause a crash.

Hazardous [Level B] - Failure has a large negative impact on
safety or performance, or reduces the ability of the crew to
operate the plane due to physical distress or a higher workload,
or causes serious or fatal injuries among the passengers.

Major [Level C] - Failure is significant, but has a lesser impact
that a Hazardous failure (for example, leads to passenger
discomfort rather than injuries).

Minor [Level D] - Failure is noticeable, but has a lesser impact
than a Major failure (for example, causing passenger inconvenience
or a routine flight plan change)

No Effect [Level E] - Failure has no impact on safety, aircraft
operation, or crew workload.

The number of objectives to be satisfied (with independence) is
determined by the software level.

Level Failure condition Objectives With independence
----------------------------------------------------------
A Catastrophic 66 25
B Hazardous 65 14
C Major 57 2
D Minor 28 2
E No effect 0 0


Note that the windows portion of the software does NOT comply with
Level C objectives.

I presume that Windows does not comply with Level B either.

And how, pray tell, can avionics that run an OS incapable of meeting
the specification be citified to it?

But last I knew, Avidyne consider the technique(s) used [to meet DO-178B] to be
proprietary. (I don't [know] what they are, but I have some educated guesses
on possible methods).

Would those methods include mordita?*

I've seen some demos of their products, which look way cool, but they are
also way too expensive for me.

But are Avidyne products that employ Windows OS reliable enough to
preclude their negatively impacting air safety?

Not much help - I know...

You know more about the subject than me. Thanks for your input.


* http://www.sandiegomag.com/forums/av...cptnmord.shtml

In article ,
Larry Dighera wrote:

Just so we are all aware of the definition of DO-178B software levels:
Catastrophic [Level A] - Failure may cause a crash.

"Failure conditions which would prevent continued safe flight and
landing."

Hazardous [Level B] - Failure has a large negative impact on
safety or performance, or reduces the ability of the crew to
operate the plane due to physical distress or a higher workload,
or causes serious or fatal injuries among the passengers.

"Failure conditions which would reduce the capability of the aircraft or the
ability of the crew to cope with adverse operating conditions to the extent that
there would be:

(1) a large reduction in safety margins or functional capabilities,

(2) physical distress or higher workload such that the flight crew could not be
relied on to perform their tasks accurately or completely, or

(3) adverse effects on occupants including serious or potentially fatal injuries
to a small number of those occupants."



Major [Level C] - Failure is significant, but has a lesser impact
that a Hazardous failure (for example, leads to passenger
discomfort rather than injuries).

"Failure conditions which would reduce the capability of the aircraft or the
ability of the crew to cope with adverse operating conditions to the extent that
there would be, for example, a significant reduction in safety margins or
functional capabilities, a significant increase in crew workload or in
conditions impairing crew efficiency, or discomfort to occupants, possibly
including injuries."


Minor [Level D] - Failure is noticeable, but has a lesser impact
than a Major failure (for example, causing passenger inconvenience
or a routine flight plan change)

"Failure conditions which would not significantly reduce aircraft safety, and
which would involve crew actions that are well within their capabilities. Minor
failure conditions may include, for example, a slight reduction in safety
margins or functional capabilities, a slight increase in crew workload, such as,
routine flight plan changes, or some inconvenience to occupants."


No Effect [Level E] - Failure has no impact on safety, aircraft
operation, or crew workload.

"Failure conditions which do not affect the operational capability of the
aircraft or increase crew workload."


[snip]
Note that the windows portion of the software does NOT comply with
Level C objectives.

I presume that Windows does not comply with Level B either.

Correct.


And how, pray tell, can avionics that run an OS incapable of meeting
the specification be citified to it?

By otherwise mitigating or controlling the hazard. For example, there could
be some other portion of the system (e.g., hardware) that is independently
monitoring the windows-based application.




But last I knew, Avidyne consider the technique(s) used [to meet DO-178B] to
be
proprietary. (I don't [know] what they are, but I have some educated
guesses
on possible methods).

Would those methods include mordita?*

If I understand the reference correctly, no.


I've seen some demos of their products, which look way cool, but they are
also way too expensive for me.

But are Avidyne products that employ Windows OS reliable enough to
preclude their negatively impacting air safety?

I don't believe that their PFDs include windows. I assume that they have
some form of Greenhill's RTOS or Windriver's OS.

The stuff with Windows is just for situational awareness, they don't perform
any functions required for safe flight.

--
Bob Noel
Looking for a sig the
lawyers will hate

Dylan Smith writes:

That's incorrect, too. During a formation flight, there will be some
communication between the formation members even when ATC is involved.

Are there a lot of GA and commercial formation flights in the air?

That's a bit like saying that smoking flying out of the back of an
aircraft should not necessarily be considered abnormal because a few
acrobatic flying teams use it.

--
Transpose mxsmanic and gmail to reach me by e-mail.