Why don't voice radio communications use FM?

"Mxsmanic" wrote in message
...

Some of the words on the cockpit recording are impossible to
understand even today.

Those are not transmitted AM or FM. They are hard wired. This seems to
defeat your point.


In fact, there are several instances of misunderstood radio
communication involved.

You keep mkaing vague references to these instances. Can you cite even one?

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,

From the NTSB and several books on the subject.


Like which?

--
Thomas Borchert (EDDH)

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:
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.

"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.

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?

Emily wrote:

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.

Then why did the aircraft start its takeoff roll, if the pilot didn't hear
what he wanted to? The tower only issued the ATC clearance, and the KLM
captain seems to have taken that as permission to take off. What else is
that but hearing what he wanted to?

James Robinson wrote:
Emily wrote:

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.

Then why did the aircraft start its takeoff roll, if the pilot didn't hear
what he wanted to? The tower only issued the ATC clearance, and the KLM
captain seems to have taken that as permission to take off. What else is
that but hearing what he wanted to?

He didn't hear ANYTHING but a heterodyne. If you want to say he heard
the heterodyne as clearance to take off, fine, but that's not what we're
talking about. The OP stated that AM results in poor transmission
quality and therefore pilots will hear what they want to hear. In this
case, the pilots heard nothing, and a high ranking captain blatantly
ignored both ATC and his own f/e.

Emily writes:

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.

There were several problems. The Pan Am crew was not sure of which
exit to take from the runway. Neither was the KLM, IIRC. The KLM
didn't understand the ATC clearance, and the tower didn't understand
the KLM acknowledgement. Pam Am said it was on the runway several
times but this was misunderstood as well. There were many
misunderstandings, most of them related to radio communication.

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.

Not entirely true. Part of it was audible.

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.

That has never been determined. The most likely cause is that a pilot
heard what he wanted to hear, or he deliberately and negligently
ignored instructions. Other pilots may also have heard what they
wanted to hear.

--
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