Real Answers from Real Pilots

Can you add and subtract degrees on a piece of paper?

Your supposed to do it quickly but I am worried if I can’t use a piece of paper as an airline pilot or regular pilot ?

I am not really sure what you are asking, but of course airline pilots can use pieces of paper. If you are asking about finding the reciprocal of a degree, I have to tell you that pulling out a pen and piece of paper to figure that out is not going to be the best look in the cockpit.

Okay but I imagine the adding and subtracting can be done in terms of degrees with a calculator or you just evolve and get better at it with practice?


Needing to use a pen and paper or a calculator is understandable for a
beginner. By the time you get to an airline you should be able to do most
calculations in your head. The hardest calculation for me was finding the
reciprocal. Then I learned a rule of thumb. Same for finding the crosswind
component. I don’t use a graph. I use a rule of thumb. Mental math is


Fly enough and you start to see patterns. Available runways at an airport like 17/35 and 9/27 etc give you some patterns to follow when thinking about reciprocals for direction. You can always glance over at a full dial HSI (typically the standby is full dial) or digital screen to get a snapshot too.

To find reciprocal of a degree, add 2/subtract 2 to the first number and the same for the second number. For example, heading 170 reciprocal is 350 because you add 2 to the first and subtract 2 from the second number. The same rule applies if the first number is greater than 2 because then you subtract the first number and add the second number (350-170)

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Or you can just add or subtract 180 :slight_smile:

Not trying to be a butt but trust me with practice it gets easier. I just spent a week in the sim. Between course intercepts and holds and I can give you the reciprocal in my sleep!