Back in 2011, I posted an article about the retirement of the Hawker Siddeley Nimrod from the Royal Air Force inventory. I referred to the Nimrod as

… expensive to buy, eye-wateringly expensive to upgrade, but it must be cheap to operate, right? No:

[…] our new fleet of refurbished De Havilland Comet subhunters (sorry, “Nimrod MRA4s”) will cost at least £700m a year to operate. If we put the whole Nimrod force on the scrapheap for which they are so long overdue right now, by the year 2019 we will have saved […] £7bn

The Register certainly got in the right ballpark with this helpful graphic:

Earlier this month, the Nimrod saga was detailed at Naval Gazing, if only as a way to show that someone can have worse procurement experiences than the United States military. Despite being a military development of a passenger jet famous for crashes, the initial marks of the Nimrod were able to meet the RAF’s needs. The problems began when a requirement was generated for a British AWACS aircraft and the Nimrod was deemed to be the best candidate for conversion (“best” probably meaning “only British competitor”):

Things began to go wrong in the mid-70s, when the British decided to introduce an AWACS aircraft to support their air defense efforts. They had several options. The E-2 Hawkeye and E-3 Sentry were both about to enter service, and were rapidly proving themselves to have excellent radar systems during trials. The British could have had either aircraft, or bought their radar systems to integrate into an aircraft of their own. Or they could have only bought a few subcomponents, like the antenna or the radar transmitter itself, and built the rest domestically.

They decided to take none of these options. Instead, they would produce an entirely new radar system. Instead of an American-style radome, separate antennas would be installed in the nose and tail, and the system would sweep through one, and then the other. This was far more expensive and much riskier than buying from the Americans, but it did produce a lot more jobs in the British defense industry, which was apparently the government’s prime concern. In 1977, a contract was placed, making BAE and GEC-Marconi co-leads on the project to convert 11 surplus Nimrod MR1 airframes to the new configuration.

As might be expected based on that kind of decision-making, the resulting airplane had problems. The computer system chosen wasn’t powerful enough to integrate all of the data, particularly the area where the nose and tail radars overlapped. It was also horribly unreliable, with a mean time between failures of only two hours, in a system which took 2.5 hours to load the mission data from the tape. The Nimrod, considerably smaller than the American Sentry, was unable to carry more equipment to solve this problem. Different electronics racks were earthed to different points in the airframe, and the resulting potential differences caused false tracks to appear, overloading the computer even more. To make matters worse, most of the electronics units weren’t interchangeable for reasons that were never entirely clear. If one unit failed, several spares had to be tried before one that worked was found. The only system that functioned reliably was the IFF system, which could only track friendly aircraft and airliners. This was a major handicap in an aircraft intended to detect incoming Soviet bombers.

It probably isn’t a surprise to hear that the planes were delayed. A lot. And delaying military projects tends to drive the overall price higher. What was anticipated to be a £200-300 million project was over £1 billion before the government of the day came to their fiscal senses and pulled the plug (they ended up buying Boeing E-3 Sentry aircraft instead).

A few years later, the RAF ran a competition to replace the Nimrod MR2 maritime patrol aircraft. Lockheed, Dassault and Airbus entered the competition, but somehow, the RAF ended up selecting BAE’s bid which involved rebuilding 30-year-old Nimrod frames with new electronics and all the modern conveniences.

RAF Nimrod MRA4 on 18 July 2009.
Detail of original photo by Ronnie Macdonald, via Wikimedia Commons.

In 1996, a contract was issued for the new aircraft, designated Nimrod MRA4. 21 aircraft were to be produced at a cost of £2.8 billion, and they would be essentially new airplanes, with only the fuselage structure being retained. The antique Spey engines would be replaced with modern BR700s. These engines were significantly larger, and required much more air, forcing BAE to design a new, larger wing. The combined effect of these two changes was to double the Nimrod’s range and improve performance. Inside, the flight deck was replaced with one derived from the A340 airliner, and the mission systems were to be all-new.

A fuselage was sent to be reverse-engineered for the design of the new wing, and BAE designed and built it, then pulled in another aircraft to make the modification. And discovered that the wing didn’t fit. Apparently, the problem dated back to the initial construction of the aircraft. When positioning the frames, Hawker Siddeley had not done what all sensible manufacturers did, and measured from a common baseline. Instead, they had positioned each frame with a tolerance relative to the previous one, which meant that the position of the wings varied by as much as a foot across the fleet. Worse, the aircraft they had designed the wings for was one of the most extreme in wing position, so the new wings didn’t fit most of the other aircraft. This forced a redesign of the wings, further delaying the program.

Spoiler: they missed their delivery deadline. By nearly a decade. And the original plan to build 21 aircraft shrank to only 4 … but the budget continued to grow, from the original £2.8 billion to over £4.1 billion at cancellation. Each of the surviving airframes had literally cost more than £1 billion. That’s why Bean gave the Nimrod his “Naval Gazing Worst Procurement Ever” trophy, and I think it was very well-deserved.