Unnecessary verbiage or sensible redundancy?

"Peter Duniho" wrote in message
...
"Tony Cox" wrote in message
ink.net...
Oh I don't know about that. 100% compliance isn't necessary, since
the two methods of announcing intentions aren't contradictory and
no additional ambiguity is introduced.

For it to do any good, you need to be able to tell the difference between
a
complete communication and an incomplete one. Without 100% compliance and
without some sort of built-in error detection, you can't. Your proposal
provides neither.

I'm still missing your point, I'm afraid. In both cases you can tell
when the transmission is complete since it'll end with "xxx traffic".
If you think I'm proposing dispensing with the full call, I'm not.
I'm not actually proposing anything - just telling you that I personally
prefer to add a "zero" to the front of a runway with one numeral,
and judging by what others have said that seems to be the preference
of the majority, even here in the US (it is apparently proper phraseology
elsewhere in the world).

I'm also saying that in this case, prepending a "zero" improves
the quality of information transfer if the transmission is truncated.

The two objections to this (pardon me if I've missed others) are
1) it's additional bandwidth, and 2) pilots might accidentally transpose
numbers. Both are valid.


And *in this particular case* (and no doubt in other scenarios
too) safety would have been enhanced had he used the "zero two"
phraseology.

How do you know he wasn't?

Because he was calling "Cherokee blah-blah, downwind, runway two".


Pilot calls "..left base, two". Could be either 2 or 20 & you know there
is an error. But you're none the wiser as to where he is. Worse case you
assume he's just being lazy with the "Jean traffic" bit & think he's on
base for 2.

How do you know there is an error? Perhaps he's landing on 2 and that was
the end of his transmission.

I know there is an error because the transmission doesn't end with
"Left Jean Traffic" or "Zero Left Jean Traffic" (0L7 has two parallel
runways). The fact that you jumped to the conclusion that he was
landing on 2 is precisely the issue in hand. He wasn't.


Pilot calls "..left base, zero". Error detected, but a reasonable
assumption
is that he is heading for 2.

How do you know he's heading for 2? Perhaps he's at a different airport,
landing on 1, 3, 4, 5, 6, 7, 8, or 9. Or even 2.

I don't know for certain, of course. He may be dyslexic. But assuming
he isn't, he could only be heading for 2 since he'd only say "zero" if he
was about to follow it with "two". Jean has only 2 one-digit runways,
2L and 2R, and he prepended his entire call with "Jean Traffic".

BTW, how does ATC call vectors? Don't they say things like "Cherokee
blah-blah turn right heading zero-two-zero", rather than just "two-zero"
?
Been a while & I can't remember.

As Steven said, three digit headings. But that has nothing to do with
calling runways, and they use single digits for single digit runways.

I think it has everything to do with it. ATC call three numbers and
pilots expect to hear three. If they don't, they know immediately that
there is an error. If it makes sense for headings, then why not for this?


It's not detecting conflicts. It's making use of degraded information.
Think of it as equivalent to a cyclic redundancy check, rather than
a parity check.

I'm afraid you need to read up on CRCs. They are simply a more reliable
error detection than a single bit parity check. They don't help you
reconstruct degraded information.

You really don't need to take my word for it. Go see what NIST
has to say. http://www.nist.gov/dads/HTML/cyclic...ancyCheck.html
CRC's *can* correct some limited types of transmission errors, whereas
parity checking can't. CRC's aren't very good at it, but that's another
matter. Just like adding that spare "zero"- it allows you to correct certain
limited types of transmission error.

Now if we could only get pilots to calculate a CRC in their
heads and append it to each transmission.......!