Context: The purpose of electronic warfare is to deny the opponent an advantage in the EMS and ensure friendly, unimpeded access to the EM spectrum portion of the information environment. Electronic warfare aircraft are used to keep airspaces friendly, and send critical information to anyone who needs it. They are often called "The Eye in the Sky." The roles of the aircraft vary greatly among the different variants to include Electronic Warfare/Jamming (EC-130H), Psychological Operations/Communications (EC-130J), Airborne Early Warning and Control (E-3), Airborne Command Post (E-4B), ground targeting radar (E-8C), range control (E-9A), and communications relay (E-11A)

Question: What is the purpose of electronic warfare?
Answer: deny the opponent an advantage in the EMS

Question: What nickname is given to Electronic warfare aircraft?
Answer: The Eye in the Sky

Question: What does the USAF use Electronic warfare aircraft for?
Answer: to keep airspaces friendly, and send critical information to anyone who needs it

Question: What is the EC-130H used for by the US Air Force? 
Answer: Electronic Warfare/Jamming

Question: What does the USAF use the E-4B aircraft for?
Answer: Airborne Command Post