Tanker aircraft are extremely vulnerable to enemy fire. If they fly within range of enemy air defense, they are little more than sitting ducks. To help overcome this problem, it seems the US Air Force is working to produce a stealthy (or low-observable) tanker called The Next-Generation Aerial Refueling System or NGAS. While high-profile aircraft like the F-22 and F-35 fighter jets tend to get attention, they can’t fulfill their missions if they are out of fuel. The US Air Force’s extensive tanker fleet is one of the key enablers of the organization.