Procedure turn in Strong X-wind

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

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.

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.

In article ,
Judah wrote:

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!

Oh, that's easy. Fly at 4500 and call up ATC for flight following. If
he yells at you about your altitude, you know you're coming from the
West.

Roy Smith wrote in
:

In article ,
Judah wrote:

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!

Oh, that's easy. Fly at 4500 and call up ATC for flight following. If
he yells at you about your altitude, you know you're coming from the
West.


Whenever I call up ATC and mistakenly tell him, "I am 10 miles West of HPN
at 4500", he always seems to get tense and tells me to ident..

Y'All,
Speaking of Math tricks. I often made my math tests for the 6-7-8 grades so
that the answers could easily be checked just by doing
the sum of the digits. Works for addition, subtraction, multiplication and
division. Find it in the Encyclopedia Britannica. Not perfect if numbers
in the answers are transposed but otherwise a quick check
when you have many papers to correct. More if you wish.
Gene Whitt

On 22 Nov 2004 22:43:11 -0800, (smackey) wrote:

OK, I'm flying my local VOR-A which calls for an outbound heading of
252, then I'm suppoosed to turn 45 deg to 207 to begin the PT. But

If it calls for a heading of 252 then I fly a heading of 252, but if
it's a course I'll add the necessary wind correction.

there is a STRONG x-wind and I am already crabbed to about 215 to hold
the 252 outbound course. I assume I turn to something not quite

I use "Kentucky windage". I'm flying here, I want to go there, the
wind is from about there and maybe something like what ATC said (give
or take 20), so I'll point about here and see what I get.

When I flew the PTS we had something on the order of a 30 to 40 knot
90 degree cross wind. I didn't use any math. The DE asked me what
I'd use for a correction angle. I told him as we had a hefty wind from
our right I'd put in about a 30 degree angle and see how it tracked
and make corrections based on that. He asked me why thirty degrees
and I replied, "It seems about right for our speed, or do you want me
to take the time to calculate it." He told me to go ahead and try it
my way and we'd see how it went. It went fine.

No, it didn't go perfect but I was able to tell him where we were and
why we were there and what I was doing to correct it.

approaching 170 (45 deg from 215), just something inbetween in order
to sort of track 45 deg off the outbound course and fly a bit longer

You are turning more into the cross wind so it'll be less of a cross
wind and more of a head wind. As a guess I'd only use about half the
wind correction in the PT as on the outbound course. It depends on
your outbound speed, but I'd add about 20 seconds in my plane. The
wind is going to be sending your back toward the inbound by the time
you are half way through your 180 and you need to allow for that early
start back.

than 1 min so I don't get blown back through the inbound course when I
do the turn back toward the inbound course. It just seems weird to be
flying at almost 90 deg from the outbound course. Any opinions on
this?

That is your heading not your course. If your wind correction is
correct you will still be coming back in at 45 degrees to the outbound
regardless of where the nose is pointed. Besides, your correction was
to the left outbound so it's going to be to the right, inbound. IE,
if you held 20 degrees left (course minus 20) then inbound it going to
be course plus 20 or 027 + 20 for 47 degrees heading to intercept a 72
degree inbound course. Also the inbound wind correction is to the
right, or 72 plus 37 for a heading of 109 degrees.

Remember your wind correction angle in the procedure turn is going to
be less than it is on the outbound and inbound approach course as it
will be either more of a head wind, or tail wind. Don't forget you
are going to be coming back to the inbound course a *lot* faster than
you went out so lead the turn inbound more than for no wind (start the
turn sooner)

I've had ATC be *way* off on the winds and blew through the ILS
intercept at 180 MPH ground speed. (at least half my fault as my
situational awareness was about 5 miles behind) I didn't make that
mistake when I took the flight test.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com