1. Considerations of safety and accuracy limit the rate of descent used in the landing approach to about 25 feet per second.

The effects of primary and runback icing and frost formations on the drag of an 8-foot-chord NACA 651-212 airfoil section were investigated over a range of angles of attack from 2 degrees to 8 degrees and airspeeds up to 260 miles per hour for icing conditions with liquid-water contents ranging from 0.25 to 1.4 grams per cubic meter and datum air temperatures of -30 to 30 degrees F.