Earlier this month, four of Washingtonâ€™s most respected public-policy â€œthink tanksâ€ offered their views on how the U.S. military posture should be organized. They differed on many issues, but one place where they all agreed was on the desirability of retiring the venerable U-2 spy plane in favor of an unmanned reconnaissance aircraft called Global Hawk. The think tanks thus sided with the fashionable consensus that the future of warfare belongs to drones rather than manned aircraft. However, this may be an instance where fashion trumped functionality. When the Air Force had to make a choice between the two aircraft in 2012, it decided the U-2S Dragon Lady was a better fit for its future needs than the RQ-4 Global Hawk â€” despite the fact that the Global Hawk was conceived to replace the U-2 and despite the fact that it could remain aloft much longer. That decision did not sit well with key members of Congress, and now there are reports the service has given up on its efforts to get rid of Global Hawk. But the Air Forceâ€™s reasons for favoring the older plane before politics intervened provide useful insight into why drones arenâ€™t necessarily the best solution for every military mission requiring an airborne system. (Disclosure: Companies engaged in building both the U-2 spy plane and the Global Hawk reconnaissance drone have contributed to my think tank; some are consulting clients.) Global Hawk is what Pentagon managers call a â€œhigh-altitude, long-enduranceâ€ unmanned aerial system, meaning a drone that can cover vast areas in a single flight with sensors capable of seeing many miles from their lofty vantage point. Prime contractor Northrop Grumman says the most common version of the drone can fly 2,000 nautical miles from its base and then loiter above areas of interest for up to 19 hours, which is something no manned aircraft could do without repeated refuelings. The droneâ€™s long reach would seem to make it well-suited to conducting reconnaissance in the Western Pacific â€“ the main geographical focus of the Obama administrationâ€™s post-Afghanistan defense posture. The Air Force recognizes the value of long endurance in sustaining continuous surveillance of potential aggressors, but when it evaluated U-2 and Global Hawk in light of its shrinking budget and the needs of regional combatant commanders, it came to the surprising conclusion that the vintage spy plane was a better bargain than the futuristic drone. Once the comparisons got beyond range, the U-2 tended to have superior performance characteristics. For starters, U-2 could fly much higher â€” at 70,000 feet versus 55,000 feet â€” which meant sensors carried on the spy plane could see considerably farther. The U-2 could also carry 67% more payload (5,000 pounds versus 3,000 pounds), and had over twice as much space as Global Hawk in which to arrange its mission equipment. In addition, the U-2â€²s on-board power generation capacity was nearly twice that of Global Hawk, meaning its diverse sensors could be operated simultaneously to collect many types of intelligence. These differences help explain why U-2 has a much higher mission-success rate in the Pacific theater than Global Hawk does â€” 96% versus 55% â€” and is selected for missions much more frequently. When an aircraft operates at 50,000-55,000 feet as Global Hawk does, it canâ€™t fly above some of the storms encountered in the Pacific the way U-2 can. Global Hawkâ€™s weather limitations are compounded by the absence of a de-icing system, which means it cannot fly through clouds for prolonged periods and thus is confined to operating in fair weather â€” unlike all the manned aircraft in the Air Force fleet. De-icing isnâ€™t the only feature left out of the Global Hawk design to save money or weight. The drone also lacks an on-board â€œsense and avoidâ€ system that would enable it to steer clear of other aircraft, whether they be commercial jetliners or enemy fighters. That means ground operators piloting the drone need a radar picture of the areas where it is flying to assure safety. If tracks from nearby ground radars are not available, then Global Hawk will require support from radar planes or other aircraft â€” an expense that typically isnâ€™t included in comparisons of what it costs to fly the two planes. Another key difference between U-2 and Global Hawk is that the drone is much more dependent on its satellite uplink to sustain flight than the manned plane. Without a continuous connection to pilots thousands of miles away, Global Hawkâ€™s ability to do anything, including simply staying aloft, is hobbled. That might not be much of a problem in peacetime, but in wartime enemies like China will be using electronic jamming, cyber attacks and anti-satellite warfare to disrupt such links, and that could severely compromise drone operations. In general, aircraft that are manned tend to be more responsive to unexpected threats than those that are remotely piloted. So some of the drawbacks associated with relying on Global Hawk for reconnaissance are traceable to the very feature that drone proponents find most appealing â€” the fact that it is unmanned. Global Hawk may not have a human on board, but it is still dependent on remote pilots to conduct operations, and the fact that they are so far away from the operating environment degrades situational awareness. Some of these limitations could be corrected by developing a bigger, more capable drone, but Global Hawks already cost over $100 million each. The superior performance of U-2 sensors compared to those carried on Global Hawk has generated pressure in Congress to figure out how said systems might be carried on the drone, but no such initiative is likely to solve the problem of how to stuff a 5,000 pound payload into a 3,000 pound bag. The head of the Air Combat Command is quoted in Defense News this week complaining bitterly about having to spend â€œbuckets of money to get the Global Hawk to some semblance of capability that the U-2 currently hasâ€ â€” and ending up with a recon fleet â€œthat is not very useful in a contested environment.â€ Much of the rationale for making this investment seems to reside in the misconception that because the U-2 debuted in the 1950s, it is antiquated. In reality, the planes flying today were built in the 1980s and are much bigger than the original aircraft. Their sensors, datalinks, displays, engines and structural features have been repeatedly upgraded â€” so much so that the airframes on average still have 50 years of service life remaining. It cost the Air Force billions of dollars to make these improvements, so the service is understandably reluctant to part with the enhanced performance the upgrades have delivered. What Air Force leaders didnâ€™t anticipate was that the political culture would be more responsive to fashionable ideas than the intelligence requirements of combatant commanders.