Altimeter Correction Cards

TangoWhiskey

TangoWhiskey

Touchdown! Greaser!
Joined
Feb 23, 2005
Messages
14,210
Location
Midlothian, TX
Display Name
Display name:
3Green
With compass correction cards, the corrections are posted in the cockpit, and you use that information to correct for installation error and deviation.

Your altimeter also has a correction card, but it's typically just found in the logbook after the 24-month altimeter checks.

Question is, based on the image below, if you were cleared in your Turbo aircraft to FL200, would you fly indicated 20000, or indicated 19880? I could find no AIM guidance on this.

attachment.php
 

Attachments

  • Screen Shot 01-27-15 at 12.32 PM.PNG
    Screen Shot 01-27-15 at 12.32 PM.PNG
    120.7 KB · Views: 170
I just read the altimeter. If it passed its 91.411 tests, it's close enough as is without sweating any error that small.
 
Ron Levy said:
I just read the altimeter. If it passed its 91.411 tests, it's close enough as is without sweating any error that small.
Click to expand...

Yup...that's why we have 1000-ft separation between IFR altitudes and RVSM requirements up to FL410, with 2000-ft separation above that.
 
MauleSkinner said:
Yup...that's why we have 1000-ft separation between IFR altitudes and RVSM requirements up to FL410, with 2000-ft separation above that.
Click to expand...

Nitpick: RVSM starts above FL 290. :wink2:

So, altimeter errors below FL 300 are quite nicely handled by the "old" rules." Not so above FL 290.
 
120 feet at 20,000...There's a reason that thing is in the logbook and not on the dash. Now if we could just get the standby compass card put there...
 
Gucci Pilot said:
120 feet at 20,000...There's a reason that thing is in the logbook and not on the dash. Now if we could just get the standby compass card put there...
Click to expand...

120 feet won't make much of a difference in a DR situation (and I'm assuming you're not discounting that possibility since you're not suggesting getting rid of the compass:wink2: ), but 3-5 degrees of error adds up fast. I'd prefer to keep the compass card.
 
Gucci Pilot said:
120 feet at 20,000...There's a reason that thing is in the logbook and not on the dash. Now if we could just get the standby compass card put there...
Click to expand...


So do controllers get annoyed watching FL199 on their display instead of FL200?
 
dans2992 said:
So do controllers get annoyed watching FL199 on their display instead of FL200?
Click to expand...

"Check your altitude. Altimeter setting is 30.11."

Bob Gardner
 
MauleSkinner said:
120 feet won't make much of a difference in a DR situation (and I'm assuming you're not discounting that possibility since you're not suggesting getting rid of the compass:wink2: ), but 3-5 degrees of error adds up fast. I'd prefer to keep the compass card.
Click to expand...

In a small airplane, if you can fly the whiskey compass within 3 degrees, you must be God's gift to aviation...especially with turbulence.

dans2992 said:
So do controllers get annoyed watching FL199 on their display instead of FL200?
Click to expand...

Your Mode C altitude readout is given to controllers in standard atmosphere pressure altitude. Doesn't matter what you put in the Kollsman window. Or what your altimeter is reading period. You could be at FL200 and crank the setting up to 30.99 and it would still show you as being at FL200 on the radar screen.
 
Last edited:
Gucci Pilot said:
In a small airplane, if you can fly the whiskey compass within 3 degrees, you must be God's gift to aviation...especially with turbulence.







Your Mode C altitude readout is given to controllers in standard atmosphere pressure altitude. Doesn't matter what you put in the Kollsman window. Or what your altimeter is reading period. You could be at FL200 and crank the setting up to 30.99 and it would still show you as being at FL200 on the radar screen.
Click to expand...


Ok, but if it's an "encoding altimeter" it will be off. It would also be off if a blind encoder had the same types of errors, right?

I am assuming that the altimeter is set to 29.92 (not that it matters as you point out though)
 
dans2992 said:
Ok, but if it's an "encoding altimeter" it will be off. It would also be off if a blind encoder had the same types of errors, right?

I am assuming that the altimeter is set to 29.92 (not that it matters as you point out though)
Click to expand...

Whether it is a stand alone encoder or built into the altimeter it is still calibrated to standard atmosphere pressure altitude. What is put in the window is irrelevant and errors in the altimeter are irrelevant. Both encoders could be off, sure. That is why it gets checked 12 & 24 calendar months. That's also why you state your altitude when you check on with ATC. That is when the controller compares what you are showing on your altimeter and what he is showing on his scope.
 
Gucci Pilot said:
In a small airplane, if you can fly the whiskey compass within 3 degrees, you must be God's gift to aviation...especially with turbulence.
Click to expand...

Maybe, maybe not. Definitely can be done if staring at the whiskey compass isn't how you have to hold a steady heading.

But if you're trying to hold the WRONG heading because you don't have a compass card, it doesn't matter how good you are.
 
You must log in or register to reply here.
Back
Top