Four months after an Indian MiG-27 fighter bomber crashed, and all Indian MiG-27s were grounded, the aircraft have been cleared to fly again. The long delay was caused by fears that all the Russian made engines in these aircraft might have a common problem. This is not a new problem. The MiG-27, and Cold War era Russian warplanes in general, do not age well. India only has about a hundred MiG-27s still operational, and all of them were grounded for over a year (2005-6) when serious problems were discovered with the MiG-27s Russian designed engines. Things have since gotten better, but not by a whole lot.
Last year, India decided to retire 60 percent of its 250 MiG-21 fighters over the next two years. The only ones remaining will be the upgraded MiG-21bis models. In the last few years, India believed it had cleared up many of the reliability problems with the MiG-21. Actually, they have, but the MiG-21 remains a dangerous aircraft to operate. India has been using MiG-21s since 1963, and has put about 800 into service. But 42 percent were subsequently lost due to accidents.
India lost 250 MiG-21s to accidents between 1991 and 2003. When consulted, Russia pointed out that India had insisted on manufacturing many of the spare parts needed to keep MiG-21s operational, and many of these parts were not manufactured to Russian specifications. While Russia does not have a reputation for making the highest quality equipment, their standards are often higher than India's. It's no secret that much of the military equipment made in India is pretty shabby by world standards.
Most of the 110 pilots lost in these MiG-21 accidents were new pilots, which pointed out another problem. India has long put off buying jet trainers. New pilots go straight from propeller driven trainer aircraft, to high performance jets like the MiG-21. This is made worse by the fact that the MiG-21 has always been a tricky aircraft to fly. That, in addition to it being an aircraft dependent on one, low quality, engine, makes it more understandable why so many MiGs were lost. And a lot were lost.
The MiG-21 problems were overcome by 2006, a year in which no MiG-21s were lost. India improved maintenance, spare parts quality and pilot training to the point that the aircraft was no longer considered the most dangerous fighter to fly. But they were more expensive to keep in safe flying condition.
While the MiG-21s and the 23/27 aircraft are distinctly different designs, all are difficult to fly and maintain. Over the last few years, all Indian MiG-23s were retired because of reliability and safety problems. The reason is simple, the aircraft are too expensive to maintain and too dangerous to fly. But India was not the only one, besides the Russians, who had problems with Russian made warplanes. During the Cold War, the U.S. had several dozen Russian aircraft they used for training their fighter pilots. Despite energetic efforts to keep these aircraft flying, their accident rate was 100 per 100,000 flying hours.
That's very high by U.S. standards. The new F-22 has an accident rate is about 6 per 100,000 hours, mainly because it's new. F-15s and F-16s have an accident rate of 3-4 per 100,000 flight hours. India, using mostly Russian aircraft, has an accident rate of 6-7 per 100,000 hours flown (compared to 4-5 for all NATO air forces.) The B-52 has the lowest accident rate of (less than 1.5 per 100,000 flying hours) of all American heavy bombers. The B-1s rate is 3.48. Compared to the supersonic B-1 and high-tech B-2, the B-52 is a flying truck. Thus the B-52, despite its age, was the cheapest, safest and most reliable way to deliver smart bombs.
New aircraft always have higher accident rates, which is how many hidden (from the design engineers and test pilots) flaws and technical problems are discovered. The F-22 is expected to eventually have an accident rate of 2-3 per 100,000 flight hours. This is part of a trend.
Combat aircraft have, for decades, been getting more reliable, even as they became more complex. For example, in the early 1950s, the U.S. F-89 fighter had 383 accidents per 100,000 flying hours. A decade later, the rate was in the 20s for a new generation of aircraft. At the time, the F-4, which served into the 1990s, had a rate of under 5 per 100,000 hours. Combat aircraft have gotten more reliable and easier to maintain, despite growing complexity, for the same reason automobiles have. Better engineering, and more sensors built into equipment, makes it easier for the user and maintenance personnel to detect potential problems. Aircraft used the computerized maintenance systems, currently common on new aircraft, long before automobiles got them. Unless you have a much older car that still runs, or a real good memory, you don't notice the enormous increase in automobile reliability. But older pilots remember, because such changes are a matter of life and death if you make your living driving an aircraft. And commanders know that safer aircraft give them more aircraft to use in combat, and more aircraft that can survive combat damage and keep fighting.
Unmanned aircraft have a much higher rate, which is largely the result of not having a pilot on board. The RQ-1 Predator has an accident rate of about 30 per 100,000 hours. Older model UAVs had much higher rates (up to 363 for the RQ-2A).