Related Clues:

• Gun at a ball game
• Air-traffic aid
• Electric eye, for one
• Sub sensor
• "M*A*S*H" character with great hearing
• 'M*A*S*H*' palindrome
• Speed gauge
• Aircraft equipment
• Security device
• Gun in a dugout
• Air-traffic detector
• Defense mechanism?
• Mine finder
• Submarine tracking device
• Airplane tracker