Altimeter discrepancy

[Gene Whitt]

Y'all,
I have been flying in an aircraft where ATC has occasionally mentioned that
there is a 3-4 hundred discrepancy betwee our
communicated altitudes and that of our blind encoder. We have
acknowledged the difference.

The altimeters were certified some 300 miles away only three months ago.

ATC has accepted continuation of our flights using our indicated altitudes
not those of the blind encoder. The transponder altituded gives encoder
altitudes..

What do the FARs require?
What are the options?
What warranty on altimeter work and for how long?
Opinions wanted.

Gene Whitt

[Mike Rapoport]

Why do you think that it is your altimeter? Does it match field elevation
with the current altimeter setting?

Mike
MU-2


"Gene Whitt" > wrote in message
k.net...
> Y'all,
> I have been flying in an aircraft where ATC has occasionally mentioned
> that there is a 3-4 hundred discrepancy betwee our
> communicated altitudes and that of our blind encoder. We have
> acknowledged the difference.
>
> The altimeters were certified some 300 miles away only three months ago.
>
> ATC has accepted continuation of our flights using our indicated altitudes
> not those of the blind encoder. The transponder altituded gives encoder
> altitudes..
>
> What do the FARs require?
> What are the options?
> What warranty on altimeter work and for how long?
> Opinions wanted.
>
> Gene Whitt
>

[Gene Whitt]

Mike,
Thanks for the reminder...
Fortunately everything is still under new aircraft warranty. Will check
papers to see kind of blind encoder feeding the transponder.
Gene


"Mike Rapoport" > wrote in message
nk.net...
> Why do you think that it is your altimeter? Does it match field elevation
> with the current altimeter setting?
>
> Mike
> MU-2
>
>
> "Gene Whitt" > wrote in message
> k.net...
>> Y'all,
>> I have been flying in an aircraft where ATC has occasionally mentioned
>> that there is a 3-4 hundred discrepancy betwee our
>> communicated altitudes and that of our blind encoder. We have
>> acknowledged the difference.
>>
>> The altimeters were certified some 300 miles away only three months ago.
>>
>> ATC has accepted continuation of our flights using our indicated
>> altitudes not those of the blind encoder. The transponder altituded
>> gives encoder altitudes..
>>
>> What do the FARs require?
>> What are the options?
>> What warranty on altimeter work and for how long?
>> Opinions wanted.
>>
>> Gene Whitt
>>
>
>

[Peter R.]

Gene Whitt > wrote:

> The altimeters were certified some 300 miles away only three months ago.

Last May I had my altimeter and encoder certified as part of the two-year
requirement. During a flight soon after, I was told by ATC that our
transponder-sent altitude was off about 400 feet when compared to the
altimeter.

After pointing this out to the shop who certified the aircraft, they
discovered that their altimeter that they use to certify aircraft had a 400
foot error in it. Nice...

--
Peter
























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[Victor J. Osborne, Jr.]

The Octal (Base 8) sections of the xponder could be out of alignment and
therefore output off by the 3-400 ft. you mention. It c/b on their end
although, I only remember "not receiving you mode C."

--

Thx, {|;-)

Victor J. (Jim) Osborne, Jr.
"Gene Whitt" > wrote in message
k.net...
> Y'all,
> I have been flying in an aircraft where ATC has occasionally mentioned
> that there is a 3-4 hundred discrepancy betwee our
> communicated altitudes and that of our blind encoder. We have
> acknowledged the difference.
>
> The altimeters were certified some 300 miles away only three months ago.
>
> ATC has accepted continuation of our flights using our indicated altitudes
> not those of the blind encoder. The transponder altituded gives encoder
> altitudes..
>
> What do the FARs require?
> What are the options?
> What warranty on altimeter work and for how long?
> Opinions wanted.
>
> Gene Whitt
>

[Roy Smith]

Peter R. > wrote: After pointing this out to
> the shop who certified the aircraft, they discovered that their
> altimeter that they use to certify aircraft had a 400 foot error

I assume test equipment like this needs to be calibrated against some
NBS-traceable standard on some periodic basis?

[three-eight-hotel]

I received an ATC notification during one flight that my altimeter was
1000' off. They actually had me turn off the altitude encoding.

This, by the way, occured shortly after having my plane in to the
avionics shop for some repairs. Turned out, when they put one of the
instruments back in the panel, they introduced a kink in the static
line. I replaced the kinked section with a new hose and everything
worked fine...