I have some basic calculations I use. Some might seem really basic, but here we go.
1. Calculate your true airspeed
I calculate this by taking the altitude in thousands of feet and multiplying it by 2. This is now a percentage value that the IAS will be increased by.
Examples:
180kts at 10,000ft => 10*2 = 20%. 20% of 180 = 36kts. 180 + 36 = 216kts TAS
300kts at 35,000ft => 35*2 = 70%. 70% of 300 = 210kts. 300 + 210 = 510kts TAS
2. Calculate groundspeed if it was unavailable.
I would note the distance travelled by the aircraft in 36 seconds, which is 1% of an hour. Then multiply this value by 100. For example, if the aircraft travelled 3.2nm then the groundspeed is 320kts.
3. Convert climb rate gradient to minimum climb rate
If you multiple the groundspeed by the climb gradient, you will find an approximate value representing climb rate.
For example, your groundspeed is 150kts and the climb gradient published on a SID is 5%. 5 x 150 = 750fpm.
4. Calculating crosswind.
Every one seems to know this, use the clock analogy. If the wind is 30 degrees off the runway, 30 on the clock would be 30 minutes, or half, so take half of the wind as crosswind.
5. Calculating headwind/tailwind.
The same as crosswind, but subtract the wind angle from ninety first. E.g. If the wind was 40 degrees of the runway at 24 knots. Take 90 and subtract 40 to give 50. With the clock analogy this is 50 minutes, or 5/6. Take 5/6 of 24 to give 20 knots head/tail wind.
6. To calculating drift
Always have in mind your max drift for the wind speed at your cruise level and the cruise TAS. Note the wind angle (which will change with time so keep looking at it). Use the same technique as 4 and 5 to calculate the total amount of drift but instead of using the wind speed, use your max drift. So if max drift was 10 degrees and the wind angle 30 degrees, take half of your max drift, or 5 degrees as your wind correction angle.
7. Calculating rate of descent on the glide
Everyone knows 5x groundspeed, or 10x div 2 which is easier.
Bodie