Before the first solo
Density altitude and crosswind. If the DA is high and the strip is short, the lesson is a briefing, not a takeoff.
Flight computer
An E6B you can actually use on a phone.
Density altitude, TAS, wind, fuel, and the 1-in-60 rule — the same face of the metal computer, without hunting for the slide. Training aid only. Cross-check the AFM and a mechanical E6B before you fly.
Photo: Dave Faige / Wikimedia Commons, CC BY-SA 3.0
Density altitude
Hot, high, and humid is how light trainers stop flying. Compute pressure altitude first, then density altitude from OAT. Use this before a summer takeoff from a short runway — then still check the AFM chart.
Pressure altitude
3,500 ft
Density altitude
5,984 ft
ISA temperature
8.1 °C
ISA deviation
+21.9 °C
Rule of thumb: DA rises ~120 ft per degree above ISA.
These numbers use ICAO standard atmosphere and the usual training-computer assumptions (no compressibility, 30 ft/hPa, 2.5 °C/1,000 ft for cloud base). They will not match a certified app to the last foot, and they must not replace the POH, a mass-and-balance, or ATC. Full terms are on the legal page.
What the metal computer is for.
On a navex
Wind triangle, time/speed/distance, fuel. Update groundspeed from actual fixes, not the forecast wind you copied at 0700.
At the airline interview
They still ask 1-in-60, TOD, and ‘what is density altitude?’ Know the why, not only the button.
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