Why don't voice radio communications use FM?

"Bob Noel" wrote in message
...
In article ,
Jim Logajan wrote:


That would definitely be a great solution, but that page was last updated
January 4, 2000. Do you or anyone else know if any further progress been
made or have the efforts died? (The links I could find all seemed to
dead-
end.)

VDL mode 2 will be coming Real Soon Now. Like all the recent CNS/ATM
mandates/changes (RVSM, 8.33, TCAS, FM immunity, TAWS, BRNAV, RNP-4,
etc etc), the move to VDL is happening way

"Sir? If the VP is such a VIP, then shouldn't we keep the PC on the QT?
Because if word leaks to the VC he could end up MIA and we'll all be put on
KP."

Mxsmanic wrote:
Peter R. writes:

A leading cause of accidents? Where did you get this statistic?

From the NTSB and several books on the subject.

Could you provide a source? I've never heard this and I know several
NTSB employees.

Mxsmanic wrote:
Emily writes:

Really? Can you cite some statistics? I'd be very interested in
reading them.

Just look through accident and incident reports. Radio communication
is one of the weak links in the aviation safety chain.

Has it ever been listed as a probable cause by the NTSB?

Mxsmanic wrote:
Peter R. writes:

A leading cause of accidents? Where did you get this statistic?

From the NTSB and several books on the subject.

Guess? If a pilot or controller is not able to comprehend the other side's
transmission, there is no guess. "Say again?" is the phrase of choice and
it is used all over the frequencies.

It's routine in linguistics to unconsciously guess. A person
listening to familiar sounds in a familiar context will "fill in the
blanks" for any sounds that cannot be unambiguously distinguished, and
he will do this without thinking. If he guesses wrong, trouble can
result, and accidents have happened in aviation for this reason (the
most famous probably being the one at Tenerife).


Actually, in the Tenerife accident, the only radio problem was caused by
simultaneous radio transmissions by aircraft, NOT a pilot hearing want
he wanted to hear. The tower told the KLM aircraft to stand by at the
same time the Pan Am aircraft transmitted, which resulted in a blocking
of both transmissions. There were many other steps in the accident
chain, but Tenerife was most certainly not caused by a pilot hearing
what he wanted to hear.

Mxsmanic wrote:
Peter R. writes:

My understanding of the accident at Tenerife is that it had more to do with
a fateful heterodyne and a captain who was asserting his own way, rather
than misunderstood communications.

Some of the words on the cockpit recording are impossible to
understand even today. That's pretty strong evidence that
misunderstood communications had an important role in this accident.
In fact, there are several instances of misunderstood radio
communication involved.


They were misunderstood a) because people were stepping on other people
and b) because the KLM crew had heavy Dutch accents. Please do a little
research before you assert such ridiculous accusations.

Mxsmanic wrote:
Peter R. writes:

With regards to aviation communication, "niner" is the proper phonetic
pronunciation of nine and "fife" is the proper pronunciation of five,
although admittedly "fife" is not as widely used as it should be.

They still sound very much the same.

Uh, no they don't.

"Emily" wrote in message
...
Mxsmanic wrote:
Peter R. writes:

A leading cause of accidents? Where did you get this statistic?

From the NTSB and several books on the subject.

Guess? If a pilot or controller is not able to comprehend the other
side's
transmission, there is no guess. "Say again?" is the phrase of choice
and
it is used all over the frequencies.

It's routine in linguistics to unconsciously guess. A person
listening to familiar sounds in a familiar context will "fill in the
blanks" for any sounds that cannot be unambiguously distinguished, and
he will do this without thinking. If he guesses wrong, trouble can
result, and accidents have happened in aviation for this reason (the
most famous probably being the one at Tenerife).


Actually, in the Tenerife accident, the only radio problem was caused by
simultaneous radio transmissions by aircraft, NOT a pilot hearing want he
wanted to hear. The tower told the KLM aircraft to stand by at the same
time the Pan Am aircraft transmitted, which resulted in a blocking of both
transmissions. There were many other steps in the accident chain, but
Tenerife was most certainly not caused by a pilot hearing what he wanted
to hear.

Correct, and FM would not have solved any of the problems. At least with AM
the heterodyne lets people know there were multiple simultaneous
transmissions. The capture characteristics of FM do away with this
sometimes useful feature.

"Steven P. McNicoll" wrote in message
ink.net...

"Ron Natalie" wrote in message
m...

No actually, it's just historical. Early av radio used AM, and for that
reason we still do.


Didn't all early radio use AM?

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

"Mxsmanic" wrote in message
...
Vaughn Simon writes:

Actually, not much does change in aviation compared with other fields of
human endeavor.

I don't think that is necessarily a bad thing. It does worry me that
the things that change in aviation are things that I'd rather see
stable. I have my doubts about fly-by-wire systems or glass cockpits,
which seem to be increasingly designed for the convenience of
programmers who grew up with Windows rather than for the convenience
of pilots.

But changing to FM would require a new radio to be
simultaneously installed in every cockpit in the world. The only way to
accomplish that would be for every plane with a new radio to transmit in
"parallel" (as someone already suggested) for a period of years on both
the new
mode and the old mode. What are the chances of AOPA allowing that to
happen?

I don't see why it would be so objectionable. It isn't even necessary
that the AM be phased out. The FM would simply be available to those
who wish to use it, for the added clarity it provides.

Why screw around with FM. It is old technology, not much beter than AM,
and there are much better technologies that would cure the communication
problems and lack of frequency availibility.

Dave Stadt wrote:
"Emily" wrote in message
...
Mxsmanic wrote:
Peter R. writes:

A leading cause of accidents? Where did you get this statistic?
From the NTSB and several books on the subject.

Guess? If a pilot or controller is not able to comprehend the other
side's
transmission, there is no guess. "Say again?" is the phrase of choice
and
it is used all over the frequencies.
It's routine in linguistics to unconsciously guess. A person
listening to familiar sounds in a familiar context will "fill in the
blanks" for any sounds that cannot be unambiguously distinguished, and
he will do this without thinking. If he guesses wrong, trouble can
result, and accidents have happened in aviation for this reason (the
most famous probably being the one at Tenerife).

Actually, in the Tenerife accident, the only radio problem was caused by
simultaneous radio transmissions by aircraft, NOT a pilot hearing want he
wanted to hear. The tower told the KLM aircraft to stand by at the same
time the Pan Am aircraft transmitted, which resulted in a blocking of both
transmissions. There were many other steps in the accident chain, but
Tenerife was most certainly not caused by a pilot hearing what he wanted
to hear.

Correct, and FM would not have solved any of the problems. At least with AM
the heterodyne lets people know there were multiple simultaneous
transmissions. The capture characteristics of FM do away with this
sometimes useful feature.

I think it's very useful. As annoying as it is to have someone out
there with a stuck mic, what would happen if messages were stepped on
and we didn't know it?