Is there a rule of thumb sort of thing to help work out reciprical headings, I fly Helis and find that my mind is a blank when having to work out a recip track , so am faced with having to list all the possibilitys for any journey at the planning stage, can I do anything better than this?... any help will be appreciated.

Many regards

Think of the 1st two figures in the 3-figure bearing as separate numbers, one of which will be larger than the other

eg 150 deg ==> 1 ---- 5 ----- 0

ie the '1' and the '5' are the figures to be considered.


Consider the larger number to be composed of '2' plus some other number, in this case '2' + '3'.

Mentally 'move' the 2 to the other figure - the '1' - and add them.

eg 150 ==> 1, 2+3, 0 ==> 1+2, 3, 0 ==> 330


There is an exception. When the 1st figure is a '3' then you would automatically treat that figure as the one with the '2' in it ie 1+2

I know it sounds long winded when written out. It's a damn sight easier to explain in person with a white board!

More examples


040 ==> 0, 2+2, 0 ==> 0+2, 2, 0 ==> 220

095 ==> 0, 2+7, 5 ==> 0+2, 7, 5 ==> 275

180 ==> 1, 2+6, 0, 0 ==> 1+2 ,6, 0, ==> 360

348 ==> 1+2, 4, 8, ==> 1, 2+4, 8 ==>168

Try

If your heading is 180 or above, subtract 180.

If your heading is less than 180 add 180.


If not not able to deal with three digits move the decimal point as you would with a runway.

EG heading 273 rw 27

(Now ask the same question but use 18 instead of 180.)

Why bother to work it out ?

Simply use a VOR or ADF dial (VOR is better), put your heading in the north position and read the reciprical from the south position.

It takes seconds and does not use up any valuable brain power.

If the track is less than 180, add 200 then knock off 20!

If it's more than 180, add 20 then knock off 200!

1. Forget the third digit, it stays the same on the reciprical as on the original heading.

2. All compass bearings start with 0,1,2 or 3.

3 Reciprocals starting with one begin with 2, 3 with 1 etc. Think about it, or better, draw a circle and split it into quarters labelled 0, 1, 2, 3. in accordance with a compass rose.

The first two figures of each bearing add up to the same as the reciprical (and 90 degrees left/right of heading.

ie reciprical of 020 ... 0+2 =2
reciprical begins with 2
2 + ? = 2

answer 200.

or, reciprical of 325 ... 3 + 2 = 5
reciprical begins with 1
1 + ? = 5

answer 145

There is one bearing that causes confusion. 1 + 0 = TEN.
therefore 2 + 8 = TEN, 1 +9 = TEN and of course 1 + 9 = TEN.

This was taught to me at West Drayton, at the Fighter Intercept Control School. When your up to your neck in crocodiles, or more accurately - Bears, Bisons, Blinders and Backfires, adding 180 is too much. The above system works and is less prone to error under stress. It was also handy setting up Lightning attacks, they wanted to approach the target at 90 degrees due to radar/missile limitations, Phantoms and Tornado like reciprocal headings.

Have fun, it does work.

I've always had a big problem with mental arithmetic in the air. Too many years of using a calculator I guess. To try and improve I wrote myself a quick mental arithmetic testing program. Although it was quite good, most flying maths is a lot easier if you know some tricks and rules of thumb, so I added some specific aviation questions to make it more applicable.

I'd be very happy to send you a copy if you'd like one - although be warned it'll be about a 3 meg file.

More or less as drizzle said. Look at something, VOR ,ADF, your DI or your protractor, and you can SEE the picture.

Ummn, BEagle has the most usual strategy. I found students were mostly able to master that technique. For the less sharp the ADF rose was always an option.

WWW

WWW

It is not a questionj of being sharp it is a question of what is easiest.

I favour the "add 200 take 20 off" method - but if the answer is more than 360 I just find it on the compass anyway...

Gentlemen, What can I say but a very big thank you to every one of you , I have printed all off, and will now see which one suits my depleting grey cells, again many thanks.
Peter R-B

Just musing out loud...

Is a reciprical heading really 180 degrees removed from the original heading?? In one way it is , but Peter talks about recip headings as a means to find a reciprical TRACK, so really he should be throwing in a double dose of drift adjustment somewhere onto the 180 shouldn't he? - or be dealing with reciprical tracks, then applying drift?

Irv

That's quite right.

To quickly calculate the heading required to maintain a reciprocal track (eg if you've just done a 180 degree turn in bad weather) the rule I was taught was to take 180 away from your heading then apply double the drift in the opposite direction ie if you originally added 10 degrees you would take off 20.