Finding Opposite Direction
Micah
of your heading. I have forgotten it and as I recall it was really simple
and quick. I don't know how I have forgotten it.
Micah
Andrew M. Sarangan
If you are in the airplane just look at the heading indicator to tell
which direction is opposite.
If you are on the ground, add or subtract 180 degrees.
--
Andrew Sarangan
PP-ASEL-IA http://lights.chtm.unm.edu/~sarangan/aviation/
Micah
look on the gyro but I was thinking of it for planning, etc. Just
remembering it too.
Thanks,
Micah
Dennis Collin wrote in message <6s5brh$j...@beast.connix.com>...
>"Micah" <thum...@nettaxi.com> wrote:
>
>>Does anyone know the simple math formula for finding the direction
opposite
>>of your heading. I have forgotten it and as I recall it was really simple
>>and quick. I don't know how I have forgotten it.
>
>>Micah
>
>Normally I just look at the opposite end of the directional gyro
>needle (grin!)
>
>
>I find this easiest for me:
>
>If your heading is less than 180 degrees add 200 then subtract 20 ...
>
> 97 + 200 = 297
> 297 - 20 = 277
>
>If your heading is more than 180 degrees subtract 200 then add 20
>
> 315 - 200 = 115
> 115 + 20 = 135
>
Dennis Collin
Jim Kuchar
> Does anyone know the simple math formula for finding the direction opposite
> of your heading. I have forgotten it and as I recall it was really simple
> and quick. I don't know how I have forgotten it.
Another trick (which also helps for finding 90 degree heading changes for
crosswind and base legs - though you should probably be looking out the window
instead) is that the digits of the headings all add up to the same amount.
Example:
360, 3+6=9
090, 0+9=9
180, 1+8=9
270, 2+7=9
things get a bit tricky for 010 and 020 however:
010, 0+1=1
100, 1+0=0
190, 1+9=10, 1+0=1
280, 2+8=10, 1+0=1
for 020, 0+2=2
110, 1+1=2
200, 2+0=2
290, 2+9=11,1+1=2
So, if you're taking off on runway 4 say, you can deduce quickly that the
other headings you'll want are all combinations that add up to 4: 2+2=220,
1+3=130, 3+1=310 -- the trick then is to figure out which is +90, -90 and
+180...
- Jim
LFransson
two/subtract two" formula. You add 2 to one of the digits, and subtract 2 from
the other like this:
Initial heading - 180
Add 2 to the 1 and subtract 2 from the 8 to get the reciprocal - 360
Going the other direction:
Initial heading - 270
Subtract 2 from 2, and add 2 to 7 to get the reciprocal - 090
Even if you do it wrong, adding 2 to 2 and subtracing 2 from 7, you get 450.
Same answer, except that now you have to do the additional math subtracting 360
to get 90.
Larry L. Fransson - ATP (CE-500), CFMEII
Macon, Georgia
"Pilots are just plane people with a different air about them."
James Brookhouser
Simply choose to either add or subtract 2 from the most significant digit,
and then perform the opposite operation (subtraction if you previously
added, or addition if you previously added) 2 to the middle digit.
Confusing to explain, but easy to demonstrate:
Say you want the 180 degree position of heading 84:
084
|... Can't subtract 2 from 0, so will add 2 to 0
|....Since I added 2 previously, I will subtract 2 from the 8.
> 264 is my answer
For 214 (will do -2/+2 here)
-2
+2
----
034 is the answer
This method does not always work (try 190...answer of 370 kind of weird,
but easily converted to 10 if you think of it), but overall this method is
easy to do in your head.
(Of course, looking at the opposite side of the H.I. works too ;)
-Jim
Micah wrote:
>
> Does anyone know the simple math formula for finding the direction opposite
> of your heading. I have forgotten it and as I recall it was really simple
> and quick. I don't know how I have forgotten it.
>
> Micah
--
James Brookhouser (970) 898-3386 j...@fc.hp.com
Fort Collins Microprocessor Lab
Hewlett-Packard Company
Tom Turton
also good for calculating 90 degrees to your heading, although it does get a
bit more complicated and it indeed might be easier just to add or subtract 90
straightaway!
Basic method, 90 degrees to the right of 114:
114 + 100 = 214
214 - 10 = 204
or 90 degrees to the left of 114:
114 - 100 = 14
14 + 10 = 24
Convoluted method, 90 degrees to the right of 350:
90 degrees will go past 360, so lets calculate 270 degrees to the
left:
350 - 300 = 50
50 + 30 = 80
Likewise, 90 left of 30 degrees: calculate 270 degrees to the right
of 30:
30 + 300 = 330
330 - 30 = 300
Told you it was convoluted!
Just remember: Dealing with 180 --> use 200/20
90 --> use 100/10
270 --> use 300/30
---Tom
Dennis Collin wrote:
> "Micah" <thum...@nettaxi.com> wrote:
>
> >Does anyone know the simple math formula for finding the direction opposite
> >of your heading. I find this easiest for me:
Nathan Kerr
reciprocal of heading + or - 2 x drift
port drift = subtract 2 x drift
starboard drift = add 2 x drift
I find the easiest way to find the reciprocal is to add 200 and subtract 20
or subtract 200 and add 20
Hope that helps,
Nathan K.
natkerr at geocities dot com
Micah wrote in message ...
>Does anyone know the simple math formula for finding the direction opposite
Gorman
2" to be the easiest by far. And, unless you're looking for the reciprocal of
the heading you're flying, it takes less time than finding, say 253 degrees on
the DG, then trying to figure out what is exactly what is on the opposite side
of that digit. Some of the other methods suggested make my eyes cross sitting
here at home, let alone trying to do the math while in the air.
This rule of thumb is probably one of the most frequently used of any that I
learned since I started flying...but then, I'm lousy at math.
Yuval Stein
The SUM of the digits of the reciprocal (and perpendicular)
direction will be the same.
for example: for heading 170 the sum will be 1+7=8,
its opposite will be 350 (3+5=8) naturally you have the
other two perpendiculars (080 and 260) but choosing the right
one is intuitive
It may seem complicated but it is actually very simple
--
Yuval Stein
Sales Executive & Senior Engineer - TechMate Division
IET - Intelligent Electronics Ltd.
Tel: 972-3-7659460 Fax: 972-3-7659401
Email: yu...@iet.co.il
Visit our WWW Home Page: http://www.iet-techmate.com/
Jim Weir
->Micah wrote:
->>
->> Does anyone know the simple math formula for finding the direction
opposite
->> of your heading.
Add 200 and subtract 20 or subtract 200 and add 20. Whichever yields a
result between 0 and 359.
Do it in your head a few times and it becomes trivially simple to remember.
Example -- reciprocal of 237 -- 137,037,047,057 Say it out loud a few
times to impress it into your memory.
Jim Weir (A&P, CFI, and other good alphabet soup)
VP Engineering, RST
Web address: www.rst-engr.com
Maurice Givens
>
> Micah wrote:
> >
> > Does anyone know the simple math formula for finding the direction opposite
> > and quick. I don't know how I have forgotten it.
>
>
> George Patterson, N3162Q.
Here is a trick I teach my ground students, and use during the ground
portion of flight reviews.
O.K.. let's say you are on a 030 deg. heading. The points on the
compass that are 90 degs, from 030 are: 120, 210, 300. Notice that
the first two numbers all add up to the same sum, namely 3 (0+3, 1+2,
2+1, 3+0). Now look at the first number. Is it an odd or even number?
For instance, for heading 120 deg. the first number is an odd
number (1). That means that the 180 deg. heading will also start with
an odd number and the first two digits will add to 3. So the 180 deg.
heading would be 300 deg.
Let's look at another example. We are heading 255 when we run into a
cloud. What is the 180 heading to get back out? 2 + 5 = 7. So the
first 2 digits of the escape heading should add to 7. Our heading
begins with an even number, the number 2. So our escape heading is
070.
Every rule has an exception. This one is no different. Let's look
at a 005 heading. The 90 degree points are 005, 095, 185, 275.
Notice that the first two digits all add to 9 except the headings
between 000 and 009.
The other problem is between 010 and 019. Let's use 015 heading. The
90 degree points are 015, 105, 195, 285. The first two digits add to
10 for headings 105,195,285, but only add to 1 for 015.
For these exceptions there is a way of using this technique. If the
heading is between 000 and 010, use 360 instead. What am I talking
about? For 000 use 360 (3+6=9), for 005 use 365 (again 3+6=9). This
may help you remember this exception.
For 010 to 019 headings, you will just have to remember that all other
headings on the 090 cardinals add to 10.
==================================================================
Maurice "Maury" Givens
--|-- COMM PILOT: ASEL, AMEL, IA - AGI, IGI
----0--(_)--0---- ma...@tellabs.com, maurice...@itu.ch
Ham Radio: N9DC, CAP: Red Fox 71
I am not even sure "I" want to accept responsibility
for what I say, much less my employer.
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BACheney
>opposite
>> > of your heading.
I usually just look at the bottom of the DG!
BACh...@aol.com
PP/ASEL 09-19-97
Jean Liddle
Gorman <Gor...@ix.netcom.com> writes:
>
> This rule of thumb is probably one of the most frequently used of any that I
> learned since I started flying...but then, I'm lousy at math.
I'm pretty good at math, and the +-2/-+2 rule is one of the most used
mnemonics I use anyway. It's so easy, so handy, and lightens the
mental workload so much (for me at least), and there are always
so many other things to be doing while planning a flight, or flying,
that I can't imagine living without it.
jean.
--
Jean Liddle +
PP-ASEL |
06-15-98 .===.
*_______ / \ _______*
http://jean.nu/ `````````----\_o_o_/----'''''''''
o' O `o
DISCLAIMER: It is unlikely that anyone shares the opinions expressed
here, much less my employer.
Dave Sutton
Use the old "Add 2, Subtract 2" trick.
For a reciprocal of 120, take a look:
120 +
180
______
300
Take the first number of "120" and add 2 (1+2=3)
Take the second number of "220" and subtract 2 (2-2=0)
use the original number for the third digit
this all adds up to 300
For 90 degrees, no first digit, so the first digit of the new
number will be 2
9-2=7
reciprocal = 270
Easy USAF issue gouge.
Dave Sutton pil...@planet.net
Yak-50, Fouga Magister, DeHavilland Vampire, MiG-17
"There is no substitute for horsepower...."