Altimeter off

[kevmor]

How can you adjust an altimeter if the pressure isn't correct in the
window for the altitude? I started talking to my examiner about it on
the checkride and he said that a lot of people adjust it themselves
(not an avionics shop, etc), and he said you take the front off (I
think) and theres a screw to adjust it? The plane would be used for
VFR only...

Is there an adjustment that can be made to the encoder as well if it's
off?

[Jim Macklin]

Not legal, you'll screw it up. Even an A&P is not allowed
to "adjust" instruments internally. You should take it to a
certified repair shop if it won't pass a IFR check. The
encoder is factory set at 1013.2 mb/29.92 and there are no
field serviceable adjustments.

If the static systems is wrong, the altimeter system and
airspeed will also likely be wrong.



"kevmor" > wrote in message
ups.com...
| How can you adjust an altimeter if the pressure isn't
correct in the
| window for the altitude? I started talking to my examiner
about it on
| the checkride and he said that a lot of people adjust it
themselves
| (not an avionics shop, etc), and he said you take the
front off (I
| think) and theres a screw to adjust it? The plane would
be used for
| VFR only...
|
| Is there an adjustment that can be made to the encoder as
well if it's
| off?
|

[kevmor]

There's no adjustments on the encoder? I can set the altimeter on the
ground to the airport elevation, so I know it should be really close
to the correct altitude, but then ATC may see my altitude as being a
hundred feet off... The encoder never needs to be recalibrated? It
just sees what is at the static input?

On Mar 20, 2:16 pm, "Jim Macklin"
> wrote:
> Not legal, you'll screw it up. Even an A&P is not allowed
> to "adjust" instruments internally. You should take it to a
> certified repair shop if it won't pass a IFR check. The
> encoder is factory set at 1013.2 mb/29.92 and there are no
> field serviceable adjustments.
>
> If the static systems is wrong, the altimeter system and
> airspeed will also likely be wrong.
>
> "kevmor" > wrote in message
>
> ups.com...
> | How can you adjust an altimeter if the pressure isn't
> correct in the
> | window for the altitude? I started talking to my examiner
> about it on
> | the checkride and he said that a lot of people adjust it
> themselves
> | (not an avionics shop, etc), and he said you take the
> front off (I
> | think) and theres a screw to adjust it? The plane would
> be used for
> | VFR only...
> |
> | Is there an adjustment that can be made to the encoder as
> well if it's
> | off?
> |

[Bill]

On Mar 22, 1:13 pm, "kevmor" > wrote:
> There's no adjustments on the encoder? I can set the altimeter on the
> ground to the airport elevation, so I know it should be really close
> to the correct altitude, but then ATC may see my altitude as being a
> hundred feet off... The encoder never needs to be recalibrated? It
> just sees what is at the static input?
>
> On Mar 20, 2:16 pm, "Jim Macklin"
>
>
>
> > wrote:
> > Not legal, you'll screw it up. Even an A&P is not allowed
> > to "adjust" instruments internally. You should take it to a
> > certified repair shop if it won't pass a IFR check. The
> > encoder is factory set at 1013.2 mb/29.92 and there are no
> > field serviceable adjustments.
>
> > If the static systems is wrong, the altimeter system and
> > airspeed will also likely be wrong.
>
> > "kevmor" > wrote in message
>
> ups.com...
> > | How can you adjust an altimeter if the pressure isn't
> > correct in the
> > | window for the altitude? I started talking to my examiner
> > about it on
> > | the checkride and he said that a lot of people adjust it
> > themselves
> > | (not an avionics shop, etc), and he said you take the
> > front off (I
> > | think) and theres a screw to adjust it? The plane would
> > be used for
> > | VFR only...
> > |
> > | Is there an adjustment that can be made to the encoder as
> > well if it's
> > | off?
> > |- Hide quoted text -
>
> - Show quoted text -

The encoder sends data as if it was always set to 2992. The ground
adjusts it for local altimeter setting.

Bill Hale

[John R. Copeland]

That is correct - there's no adjustment on the encoder.
Your encoder reports density altitude to ATC.
ATC computes an altitude correction factor for their own displays.
Some cockpit instrumentation computes the identical correction,
allowing the pilot to know what altitude ATC is displaying.

"kevmor" > wrote in message oups.com...
> There's no adjustments on the encoder? I can set the altimeter on the
> ground to the airport elevation, so I know it should be really close
> to the correct altitude, but then ATC may see my altitude as being a
> hundred feet off... The encoder never needs to be recalibrated? It
> just sees what is at the static input?
>
> On Mar 20, 2:16 pm, "Jim Macklin"
> > wrote:
>> Not legal, you'll screw it up. Even an A&P is not allowed
>> to "adjust" instruments internally. You should take it to a
>> certified repair shop if it won't pass a IFR check. The
>> encoder is factory set at 1013.2 mb/29.92 and there are no
>> field serviceable adjustments.
>>
>> If the static systems is wrong, the altimeter system and
>> airspeed will also likely be wrong.
>>
>> "kevmor" > wrote in message
>>
>> ups.com...
>> | How can you adjust an altimeter if the pressure isn't
>> correct in the
>> | window for the altitude? I started talking to my examiner
>> about it on
>> | the checkride and he said that a lot of people adjust it
>> themselves
>> | (not an avionics shop, etc), and he said you take the
>> front off (I
>> | think) and theres a screw to adjust it? The plane would
>> be used for
>> | VFR only...
>> |
>> | Is there an adjustment that can be made to the encoder as
>> well if it's
>> | off?
>> |
>
>

[Peter Clark]

There's no user-adjustable settings on the encoder, but there are
adjustments on the encoder (assuming an encoder, not an encoding
altimeter) which can be made, assuming the unit itself is not just
busted, by an avionics shop and a transponder test set which will
bring it back into spec.

On Thu, 22 Mar 2007 15:56:42 -0400, "John R. Copeland"
> wrote:

>That is correct - there's no adjustment on the encoder.
>Your encoder reports density altitude to ATC.
>ATC computes an altitude correction factor for their own displays.
>Some cockpit instrumentation computes the identical correction,
>allowing the pilot to know what altitude ATC is displaying.
>
>"kevmor" > wrote in message oups.com...
>> There's no adjustments on the encoder? I can set the altimeter on the
>> ground to the airport elevation, so I know it should be really close
>> to the correct altitude, but then ATC may see my altitude as being a
>> hundred feet off... The encoder never needs to be recalibrated? It
>> just sees what is at the static input?
>>
>> On Mar 20, 2:16 pm, "Jim Macklin"
>> > wrote:
>>> Not legal, you'll screw it up. Even an A&P is not allowed
>>> to "adjust" instruments internally. You should take it to a
>>> certified repair shop if it won't pass a IFR check. The
>>> encoder is factory set at 1013.2 mb/29.92 and there are no
>>> field serviceable adjustments.
>>>
>>> If the static systems is wrong, the altimeter system and
>>> airspeed will also likely be wrong.
>>>
>>> "kevmor" > wrote in message
>>>
>>> ups.com...
>>> | How can you adjust an altimeter if the pressure isn't
>>> correct in the
>>> | window for the altitude? I started talking to my examiner
>>> about it on
>>> | the checkride and he said that a lot of people adjust it
>>> themselves
>>> | (not an avionics shop, etc), and he said you take the
>>> front off (I
>>> | think) and theres a screw to adjust it? The plane would
>>> be used for
>>> | VFR only...
>>> |
>>> | Is there an adjustment that can be made to the encoder as
>>> well if it's
>>> | off?
>>> |
>>
>>

[Dave Butler]

John R. Copeland wrote:
> That is correct - there's no adjustment on the encoder.
> Your encoder reports density altitude to ATC.

Make that "pressure altitude".

[John R. Copeland]

"Dave Butler" > wrote in message ...
> John R. Copeland wrote:
>> That is correct - there's no adjustment on the encoder.
>> Your encoder reports density altitude to ATC.
>
> Make that "pressure altitude".

Oops! I really *do* know that.
I just screwed up. Thanks, Dave.

[kevmor]

Thanks all for your advice, I also had a problem once or twice with
this transponder on the last digit not showing correctly on their
side. ATC asked to confirm my squawk a couple times, and then I
suppose he got a supervisor who said "the last digit of your
transponder...what does it read?" He told me to rotate the knob around
a few times, which fixed it. The airplane was set on 1200 and never
changed for a decade, maybe it just needed to be cycled some :)

Dave Butler wrote:
> John R. Copeland wrote:
> > That is correct - there's no adjustment on the encoder.
> > Your encoder reports density altitude to ATC.
>
> Make that "pressure altitude".

[Jim Macklin]

"John R. Copeland" > wrote in
message ...
That is correct - there's no adjustment on the encoder.
Your encoder reports density altitude [PRESSURE ALTITUDE]
to ATC.
ATC computes an altitude correction factor for their own
displays.
Some cockpit instrumentation computes the identical
correction,
allowing the pilot to know what altitude ATC is displaying.

"kevmor" > wrote in message
oups.com...
> There's no adjustments on the encoder? I can set the
> altimeter on the
> ground to the airport elevation, so I know it should be
> really close
> to the correct altitude, but then ATC may see my altitude
> as being a
> hundred feet off... The encoder never needs to be
> recalibrated? It
> just sees what is at the static input?
>
> On Mar 20, 2:16 pm, "Jim Macklin"
> > wrote:
>> Not legal, you'll screw it up. Even an A&P is not
>> allowed
>> to "adjust" instruments internally. You should take it
>> to a
>> certified repair shop if it won't pass a IFR check. The
>> encoder is factory set at 1013.2 mb/29.92 and there are
>> no
>> field serviceable adjustments.
>>
>> If the static systems is wrong, the altimeter system and
>> airspeed will also likely be wrong.
>>
>> "kevmor" > wrote in message
>>
>> ups.com...
>> | How can you adjust an altimeter if the pressure isn't
>> correct in the
>> | window for the altitude? I started talking to my
>> examiner
>> about it on
>> | the checkride and he said that a lot of people adjust
>> it
>> themselves
>> | (not an avionics shop, etc), and he said you take the
>> front off (I
>> | think) and theres a screw to adjust it? The plane
>> would
>> be used for
>> | VFR only...
>> |
>> | Is there an adjustment that can be made to the encoder
>> as
>> well if it's
>> | off?
>> |
>
>

[[email protected]]

On Mar 20, 11:53 am, "kevmor" > wrote:
> How can you adjust an altimeter if the pressure isn't correct in the
> window for the altitude? I started talking to my examiner about it on
> the checkride and he said that a lot of people adjust it themselves
> (not an avionics shop, etc), and he said you take the front off (I
> think) and theres a screw to adjust it? The plane would be used for
> VFR only...
>
> Is there an adjustment that can be made to the encoder as well if it's
> off?

http://www.cozybuilders.org/newsletters/news_30.html
It's easy enough to do if you want to. BUT

It's a) not legal and b) adjusting the altimeter at your airport
elevation may make it totally out of spec at cruising altitude. The
instrument shop adjusts it so that it's in spec over the entire range
of altitudes, not just correct at one particular one.

Ed

[B A R R Y[_2_]]

kevmor wrote:
> The airplane was set on 1200 and never
> changed for a decade, maybe it just needed to be cycled some :)

Don't feel bad.

We use ours pretty much every time we leave the pattern, and sometimes
we still have to do a full spin to clean the contacts. With us, it's
normally the first digit, as ours normally always seems to be a 1, 5 ,
or 0. The 2, 3, 4, and 6, and 7 sometimes get dirty in that slot.

Now that I think about it, I can't believe how often I'm told to squawk
5304. G>