Compass

Should air carriers conduct compass swing at regular intervals?

Without verification..... I believe the old style "Wet Compass" needs calibration once a year. This is not to say it must come off the aircraft and go to shop, but rather taking the aircraft out to a compass rose (which hardly any airports have any more) and checking the compass on 30 degree radials.

With a digital standby compass, I would say spinning the aircraft is not needed.

It really is a joke though..... if you're down to just the standby compass for navigation, your problems are much larger than just what heading you're on.

Each airline should state requirements needed in their GMM or General Maintenance Manual.

Why do wet compass need calibration annually?

Well.....

Here's the compass card from an aircraft coming into our fleet.
  
     
  
A tad out of date???

I haven't had a moment to look at my company's GMM to see if there are specific requirements for standby compass indicators.

As far as the newer liquid crystal compass (incorporated with standby attitude/air data), it receives initial heading from the IRS's. It will only use its own internal circuitry if IRS info is lost.

Wet compass's (to me) should be verified once a year, because they are stand alone mechanical units.

Every once in a while..... thay do leak. What is the liquid???? Varsol.

Another one out of date. I would guess the FAR's have changed on certification requirements.....
  
     
     
 

We swing our compass every 3 years another method you can use is the "Moses compass" not sure the proper name. 

 

This tool goes on a pole and you align the front and back of the aircraft with the sights, like a gun sight. Turn t the aircraft until the mag compass in the aircraft reads dead north for example walk out in front 30 or so feet then check it against the tool it's already 180 flipped so even though it's faced the opposite way it will read the same as the aircraft. If the aircraft compass doesn't read the same as the tool that's your deviation.