Aviation Rules of Thumb

#1 - 1. To find ground speed note the time required to fly a published distance.
2. Pick a number that when multiplied by the flight time yields approximately 60.
3. To get that ground speed, multiply that number by the distance.

example: 15 minutes is required to fly 30 nm (4*15=60). Ground speed equals 120 kts (4*30=120)

#2 - For relatively fast aircraft (at least 250 kts), the quickest way of calculating Ground Speed using the DME (without G/S readout) is to note the distance travelled in 36 seconds. 36 seconds = 1% of one hour.

example: If you travel 3.25 nm your Ground Speed is 325 kts