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B744 Mag Compass Question

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While flying, I noticed the magnetic compass located just under the lights panel in the centre looks a bit odd on the 747. I'll try to explain the best I can... :-)The ND (and even the heading indicator on the PFD) is 'normal' in that say you're flying south, it shows your heading as 180

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The ND displays like a flat compass, so all the directions are normal. The standby compass is a ball, and so the pilots can see the reading, the numbers have to be reversed, as do the direction.For example, when you fly the north, the compass points north, but the north text for the pilot has to be painted on the south side of the ball, as that's the part thats displayed. If you turn right 10 degress, onto 010, the compass will turn left to continue pointing to north. Which also means the compass will have to rotate left to get to 010. I don't know if that explains it, but it make sense when you think about it for long enough!!It has to be done this way, as the compass is mounted against the front windscreen area, and so you can't look down at it from above, which is the normal way of reading a compass.


Phil Brown

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I had a two hour flight one night without gyro... learned to fly the compass. The trick is to imagin the compass is stationary then a change in heading becomes a "walk around the compass." Compass flying is basic airmanship, most pilots learn the memory aid ANDS UNDS to remember that the compass turns North in acceleration, South in Deacceleration, undershoots turning North and overshoots turning South. At least, that's what I recall.


Dan Downs KCRP

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"the compass turns North in acceleration, South in Deacceleration, undershoots turning North and overshoots turning South."You should see what happens when you put a magnetic-tipped screwdriver near it by accident :PPPInterestingly, during beta testing of the original 744, I recall that the compass WAS turning in the same direction as the PFD/ND compasses. To do that, the whiskey compass would have to be motorized (It was soon rectified :( )Cheers.Q> イアン

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Does somebody remember the Douglas solution on their DC8-60 series?The Compass was installed high above and behind Captains seat, with a small mirror on the glareshield panel. Worked like a charm regarding turn direction.Never had to use the system in that way for heading info.And de mirror itself? Was frequently used and lined up to see what was going on behind, through the (then open) cockpit door, all the way to the aft galley.Greets,Harry

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