Why Bombers Attacked At Higher Altitudes

Flak Effectiveness

Bomber loss rates from flak are strongly dependent on the attack altitude.

According to the Comparative Study of Reports on Bombing Accuracy and Flak Risk, the effectiveness of heavy AA defenses is at a maximum of about 7,500 feet altitude. Also, from 15,000 to 30,000 feet, the effectiveness decreases by roughly 50% for each 5,000-foot increase in altitude.

A rule of thumb is that flak is that the risk of a flak hit is decreased by half for every 5,000 feet of elevation. Losses from flak decrease in altitude, the higher, the fewer. The rule is to fly at the highest altitude practical consistent with desired bomb accuracy.

Flak is quite accurate at 15,000 ft. but it becomes less accurate with altitude so at 20,000 ft. it is only one-half as accurate as it was at 15,000 ft. At 25,000 ft. its accuracy is then reduced by half. At 30,000 ft. accuracy is cut in half. In general, flak accuracy is decreased by half for every 5,000 ft increase in altitude.