Complex sentence: Observing the map from above, group commanders could track the movements of enemy aircraft through their patch, examine the tote board, select a squadron and called their sector to have them scramble.
Split into simpler sentences: Observing the map from above, Group Commanders could track the movements of enemy aircraft through their airspace. When the time was right, they examined the tote board, selected an available squadron, and called their Sector to have them scramble.