Rules of Thumb

As a pilot you learn several rules of thumb that you can use to quickly make computations in your head such as the descent rate on an ILS, wind correction angles etc.

In this document I’ve summarised several such rules of thumb and also added some other reference information that can come in handy, such as unit conversions, how to determine holding entries, phonetic alphabets (English and Swedish), etc.

Generally, the rules of thumb will give results within 5% of the correct value. If not, I’ve added an estimate of the error. In some cases I’ve given hints on how to do a computation in your head, e.g.

1 US gal ≈ 3.79 l [× 4 – 5%]

This means that to convert US gallons to litres, you can multiply by 4 and subtract 5% of the result. So to convert 10 gallons you first get 10×4=40, then subtract 5% of 40, which gives 40-2=38 litres, which is off by only 0.1 litres.

The two-page document is in US half-letter format (the one used by Jeppesen) and should be printed on both sides of the paper. Printing on international standard A5 paper also works.