Despite their age, the B-52 heavy bombers of the U.S. Air Force continue to be upgraded and updated. These were elderly (built in the early 1960s) B-52s have proved to useful to ignore. The latest upgrade was more of a reliability test. In mid-2017 there was a test of the bombers ability to drop the PDU-5 leaflet bomb. This is a variant of the cluster bomb long carried by B-52s. But instead of dispersing 247 bomblets from a larger canister the PDU-5 disperses 60,000 leaflets over several square kilometers. The PDU-5 has been used regularly since 2001 to warn people (usually in target areas) that a bombing or artillery attack is coming. Normally PDU-5s are delivered by jet fighters but helicopters have been used and the test drops from the B-52H is to ensure that there are no problems with the bomb colliding with the aircraft once dropped.
The B-52 PDU-5 test wasn’t an upgrade as much as standard safety check. The B-52H has a better reliability record than much more recent aircraft and much smaller aircraft. For example the U.S. Air Force mission capable or “readiness rate” (percentage of available aircraft able to do their job) varies by type and technology. Age has less to do with it than you might think. As of 2015 the B-52H rate was 72 percent compared to 47 percent for the B-1B heavy bomber and 71 percent for the F-15E fighter bomber.
The last round of hardware upgrades was in 2015 and included installing some improvements to the aircraft electronics. That came a few years after another upgrade that enabled B-52 crew to program (enter GPS coordinates for a target) smart bombs carried internally. Previously only the smart bombs carried under the wings could be programmed by the crew. This upgrade simply means wiring the bomb bay so that smart bombs can be plugged into the aircraft fire control system. This was important because that made it possible to carry other programmable weapons like the MALD (radar and anti-aircraft missile decoys) and the JASSM (long range smart bombs used for taking out enemy air defenses). By 2017 about half the B-52s had their bomb bay wiring upgraded.
A decade ago the B-52 was modified so it could carry over a hundred of the 130 kg (285 pound) Small Diameter Bombs (SDB, also known as the GBU-39/B). Back in 2006, the rotary bomb rack inside the B-52 was modified to carry 32 SDBs instead of 15 larger bombs. The B-52 could already carry more SDBs under its wings using special racks that held 4 SBDs where one larger bomb would normally be.
Until the recent upgrades, the SBDs carried internally had to receive their target coordinates on the ground, not in the air. The ability to enter or change GPS coordinates in smart bombs is necessary now because heavy bombers typically stay in the air over the combat zone for 8 hours or more at a time, delivering smart bombs as needed by troops on the ground. The B-52 also has its own targeting pod now that enables the crew to spot targets, program one of its smart bombs, and take them out without needing GPS coordinates from someone on the ground.
This greater bomb carrying capability makes the B-52 even more effective, as it is cheaper to have one "bomb truck" over the combat zone rather than several fighter-bombers. With a max takeoff weight of 240-250 tons the BUFF (Big Ugly Fat Fellow) is basically a large aircraft designed to carry bombs cheaply and efficiently. The readiness rate of these bombers remains high because it was not designed to operate at supersonic speed or carry out stressful maneuvers. Although 60 years old, most of the internal gear has been replaced with modern electronics and furnishings. It’s all flat screens and modern gear. Look closer and you see a lot of 60 year old metal.
The B-52 is one of the cheapest (along with the B-1B) to operate heavy bombers in the air force, and one of them can cover all of Afghanistan. These B-52s are often based on the Indian Ocean island of Diego Garcia and from there can support operations in Iraq and Afghanistan. In late 2001, ten B-52s dropped a third of the bomb tonnage in Afghanistan. That's a remarkable record for a 60-year-old aircraft design. The B-52 carried that much of the load because it was the most cost-effective American heavy bomber. The B-52 also has a lower accident rate than the B-1 and B-2. Compared to the supersonic B-1 and high-tech B-2, the B-52 is just a flying truck. Thus the B-52, despite its age, was long the cheapest, safest, and most reliable way to deliver smart bombs over Afghanistan. In the last few years the B-1B became the cheapest (per flight hour) heavy bomber to operate but not by much and mainly because the cost of maintaining a 60 year old aircraft gets higher with age simply because more things wear out and have to be replaced. But because of its large bomb load and ability to handle smart bombs the B-52H is one of the cheapest ways to deliver a smart bomb.
For example, over Afghanistan, carrying a dozen 909 kg (2000-pound) JDAM (GPS-guided bombs) or a larger number of smaller bombs, a B-52 could circle a combat area for hours, waiting for the special force guys or Air Force controllers on the ground to send them the coordinates of a target. The JDAM landed (over 90 percent of the time) within 16 meters (50 feet) of the location the ground troopers wanted it. Better yet, most of the bombs arrived within 10 minutes of the request.
The B-52 was the principal heavy bomber throughout most of the Cold War (1947-91). The B-52 prototype first flew in 1952. The last one built, a B-52H, was in 1962. The B-52 has seen a lot of action in Vietnam, the Persian Gulf War, in the Balkans, and over Afghanistan. It has a crew of five (pilot, copilot, navigator, electronics warfare officer, and radar navigator). There used to be a gunner for a rear-firing 20mm cannon but this was eliminated in the 1990s. Automation can reduce crew size even more. The 1970s era B-1B has a crew of four, and the 1980s era B-2 has a crew of two. The only B-52s flying are the B-52H model, which has been much modified since the last one rolled off the assembly line.
A true replacement for the B-52 was never built because no one foresaw the development of such accurate smart bombs and the ability of the U. S. Air Force to destroy most anti-aircraft defenses. Indeed, even when faced with heavy defenses, the B-52 was able to fight its way through. During the twelve days of Linebacker II raids against North Vietnam in 1972, 15 B-52s were shot down by Soviet-built SAM-2 missiles. The 150 B-52s stationed in Guam flew 729 missions, for a loss rate of 2 percent. But because of the number of sorties flown, 10 percent of the B-52s involved were brought down. Of the 92 airmen in the downed aircraft, 33 died.
After Vietnam the B-52s received several generations of new electronic warfare equipment, learning much from the experience during Linebacker II. But there never was enough money to keep the B-52 completely up to date, especially with the equipment needed to use some of the newer bombs. As a result, some B-52s got their JDAM equipment just before the 2001 war in Afghanistan. The B-52 was upgraded to use JDAM before the B-1B because the B-52 is more reliable. In any event, the upgrade was cheap - wiring from the weapons officer's station to the bombs so GPS location data could be changed in flight. The 50-year-old B-52 soon became the weapon of choice over Afghanistan, able to hang around for hours and drop one-ton JDAM bombs on demand.
Currently, the Air Force has the capacity to shut down the high-altitude missile systems of just about anyone and then bring the B-52s in at high altitude to avoid low-altitude anti-aircraft guns and mobile antiaircraft missile systems. The B-1B and B-2 were built to deal with even more intense antiaircraft defenses they would face in the Soviet Union. But with the collapse of the Soviet Union in 1991, no one else had such an air defense system. Perhaps, in the future, a nation like China may build another such formidable antiaircraft defense system. For the moment, because of the lack of first rate air defenses to stop it, the B-52 can still hack it in the combat zone, even delivering nuclear weapons.
Currently the air force expects to keep some (as many as fifty) B-52H bombers in service until the 2040s.