What is the rule of thumb for calculating DENSITY ALTITUDE?

The rule of thumb for calculating density altitude is to add 120 feet to the pressure altitude for each degree above standard temperature. For example. If you pressure altitude was 700 feet and the temp was 28 degrees Celsius you would add 1560 feet to your pressure altitude giving you an approximate density altitude of 2260 feet. Remember high temperatures, high humidity, high altitudes, and low pressure all contribute to raising the density altitude.

spiral Archives - Runup.ca

Spiral dives can easily develop if you find yourself in clouds or poor visibility. Once you enter a spiral dive you might only have 178 seconds to live! The ability to recognize the spiral and recover can save you and your passengers lives. The key is interpreting what your instruments are telling you. You will be able to sense a spiral dive on a beautiful day with great visibility, but it is much harder to recognize the behaviour of the aircraft when everything is white.