Review the following resources on density altitude and its effects on flying:
Hot, High, and Heavy-The Deadly Cocktail of Density Altitude (PDF),
Don’t Be Dense About Density Altitude (Plane and Pilot).
Density Altitude (Mountain Flying)
Density Altitude (PDF) (Federal Aviation Administration)
The following video is a historic mid-century FAA film discussing the important aspects of density altitude:
Density Altitude with Harry Bliss (YouTube – 29:00)
This video, from the view of the cockpit, captures the density altitude-related crash of a general aviation aircraft:
Airplane Crash In-Cockpit Footage: Stinson 108-3 (YouTube – 3:50)