The U.S. Air Force is having second thoughts about replacing all of its manned U-2 reconnaissance aircraft, with Global Hawk UAVs, in the next five years. Human pilots still have an edge over robotic systems, especially when it comes to emergencies. But another advantage the U-2 has is that it has been around for half a century. Its quirks and foibles are well known. The Global Hawk is not only new, but is also the first of a new kind of robotic aircraft. Global Hawk has crossed the Pacific, from North America to Australia, using onboard computers to run everything. While impressive, Global Hawk still has a tendency to get into trouble unexpectedly, and not know how to recover. More work needs to be done on the software and, to a lesser extent, the hardware used by Global Hawk. Since no one can (or at least will) swear when Global hawk reliability will be up to acceptable standards, plans are being made to keep the U-2s around for a while longer. Just in case.