The U.S. has started moving RQ-4A Global Hawk UAVs to Guam, where a unit of them (the 12th Reconnaissance squadron) will be stationed. The first RQ-4 landed in Guam on September 1st, and about six more will follow. These RQ-4s are travelling via a shorter northern route, over Canada. In Guam, these high flying aircraft have lots of work. The squadron in Guam will handle missions over Korea and off the Chinese coast. The U.S. is also starting to use RQ-4s as satellite substitutes to track hurricanes (and the larger typhoons in the Pacific) as well as keeping an eye on major volcanic eruptions (and the large clouds of dangerous, to jet aircraft, of volcanic ash and grit.) The RQ-4s fly above storms and volcanic ash clouds, at up to 19,500 meters (60,000 feet).
It was only two years ago that a RQ-4 made the first non-stop crossing of the Pacific, flying 12,000 kilometers, from California to Australia, in 23 hours. The Global Hawk had previously crossed the Pacific in several hops, but it always had the endurance to do it non-stop. Now the trips is being made via the shorter (18 hours to Guam) northern route as well.
In the last nine years, RQ-4s have flown over 45,000 hours, most of that combat missions, and many of them from Persian Gulf and South Asian bases. The latest models have been able to fly 20 hour missions, land for refueling and maintenance, and be off in four hours for another twenty hours in the sky. The RQ-4 has been very reliable, with aircraft being ready for action 95 percent of the time. The U.S. Air Force has been buying them at the rate of five a year, at a cost of $35 million each for the basic aircraft. Include payload (sensors and communications) and development costs, and it averages over $120 million each.
The new B version is about ten percent larger (wingspan of 42.3 meters/131 feet, and 15.5 meters/48 feet long) than the A model, and can carry an additional two tons of equipment. To support that, there's a new generator that produces 150 percent more electrical power. The B version is a lot more reliable. Early A models tended to fail and crash at the rate of once every thousand flight hours, mostly because of design flaws.
The first three RQ-4Bs entered service in 2006. At 13 tons, the Global Hawk is the size of a commuter airliner (like the Embraer ERJ 145), but costs nearly twice as much. Global Hawk can be equipped with much more powerful, and expensive, sensors, than other UAVs. These more than double the cost of the aircraft. These spy satellite quality sensors (especially AESA radar) are usually worth the expense, because they enable the UAV, flying at over 60,000 feet, to get a sharp picture of all the territory it can see from that altitude.
The U.S. Navy is also buying Global Hawks, up to 44 of them, to perform maritime reconnaissance. As a result of that decision, Australia is likely to buy some as well, to monitor the vast stretches of ocean that surround the island continent. Germany is buying the RQ-4, and NASA uses two of them.