Intermittent flag warnings on the altimeter can be a nuisance. You never know when they are going to show up, and you're not always sure what they are about. Then they can disappear just as suddenly when you tap on the glass.
They are also easy to dismiss, especially if you're flying in VFR conditions and nothing in your field of vision gives you cause for concern. But one thing is for certain, you should not ignore flag warnings.
Ignoring a flag during VFR can be tempting, but it is a bad habit to get into. The next time it shows up may be during IFR conditions, and that could be a dangerous situation.
Flag issues can be intermittent, showing up once in a great while or constant, always in view. Some units have test buttons on the front that you can press to test the movement of the pointer and flag operation.
Push that button and the pointer will usually move a few hundred feet, and the flag drops into view during the movement. When you release the button, the pointer comes back, and the flag goes away. If it does not go away, this could be an indication of a sticky flag or some other internal problem.
To test the unit, swap it out of the panel with a similar unit. If the flagging problem goes away, the unit needs to be sent in for repair. If it continues, it could be something in the aircraft causing it.
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