I absolutely agree... I was just answering the question of why the math
"trick" works.

In flight I can't think about Math - I have to concentrate on things like
remembering whether I am coming from the East or the West!




Roy Smith wrote in
:

In article ,
Judah wrote:

Jose wrote in
. com:

The 90/270 has a tremendous advantage when making turns and
remembering where to turn.

The system is called the 'sum of the digits'

Take any number of the heading indicator and add all three of
its digits and keep adding until you get a single digit... (math
snipped)


Cool piece of math (even more interesting =why= it works, and how it
translates into other bases). However, to find my entry, I just
look at the DG and pick the number that's off to the side. I turn
there, then turn opposite onto the course. No math needed. The ten
degrees one way or another doesn't make any difference.

Jose

Because you're adding 90 to the numbers each time, and our math system
is 10-based. If you add 9 to any number in a 10 based system, you are
adding 1 to the 10's digit, and subtracting 1 from the 1's digit. The
result is if yo uadd the new digits, they will equal out.

It's easier to see if you take a single digit number, add 9, and add
the digits... It will illustrate the same point.


1 + 9 = 10 1+0 = 1
2 + 9 = 11 1+1 = 2 3 + 9 = 12 1+2 = 3

I used to know enough math to be able to solve differential equations
(well, the easy ones anyway), but when I'm flying an airplane in the
clouds, I don't want to waste any of my limited and precious remaining
neurons on subtraction.

The way I make a 90 degree turn is:

1) Move the heading bug until it's pointing sideways.

2) Turn the plane until the heading bug is pointing upright again.