According to the U.S. Air Force, the RQ-4A Global Hawk, which has been in action for over three years now, is not officially ready for regular service. There are a number of reliability tests that have to be performed before the UAV can leave the development stage. Reliability has been a major issue, especially with a UAV that costs $30 million. The current generation of UAVs, using much more capable software than earlier models, is treated much like a manned aircraft. But without a pilot on board, many problems that a pilot could deal with, instead lead to the loss of the UAV. This has been a worrisome problem with Global Hawk, as well as the smaller (and cheaper, at $4 million each) Predator. So the latest A versions contains a number of software and hardware changes that are supposed to solve many reliability problems. The coming series of operational assessment flights this Spring will determine if the aircraft design is ready for mass production. 

The air force is planning to produce 51 RQ-4s, including two for the U.S. Navy. The production versions of the Global Hawk will be the RQ-4B. The B version is larger (wingspan is 15 feet larger, at 131 feet, and its four feet longer at 48 feet) and can carry an additional two tons of equipment. To support that, theres a new generator that produces 150 percent more electrical power. The first three RQ-4Bs wont enter service until 2006. The aircraft costs $18 million, and the sensor and communications electronics another $10-12 million.