more quickly. A coordinated turn in such circumstances is essential. Somewhere in the turn it all became too much for the powerful engine to overcome. The pilots lost control and impacted terrain. Force of impact increases by the square of the speed. Increased density altitude results in higher ground speed for a given indicated airspeed. The final density altitude consequence levied on the two friends would be a higher speed at ground impact and a more destructive crash. Neither pilot survived. Density altitude affects every Mountain flying allows pilots to reach new and exciting destinations while providing adventures and challenges that most flatlanders will never know. As with any new flying adventure, there are also unique risks, most associated with either unforgiving terrain or high density altitude. Go beyond the textbook with the AOPA Air Safety Institute's Mountain Flying Safety Spotlight. airsafetyinstitute.org/spotlight/mountainflying airplane. It's one of the more difficult concepts to comprehend. We all are taught about it, but it's an abstract concept until we see it for ourselves and experience the degraded aircraft performance in context. The flatland pilots in this tragedy linked several critical decisions together. They took off at 6 p.m., likely believing at that time of day the density altitude would have been manageable. They assessed-guessed, actually- that after several circuits they had enough aircraft performance to fly up and over an unknown canyon. They didn't anticipate the potential effects of " sinkers, " downdrafts coming over the mountains in front of them, from atypical winds at altitude. Finally, they waited too long in their decision to turn back. Density altitude is a stealthy killer. You don't realize it's got you trapped until it's too late. richard.mcspadden@aopa.org AOPA PILOT / November 2021 79http://www.airsafetyinstitute.org/spotlight/mountainflying