It was 1960. A time when there was no difference in the Soviet Union between the Military Rocket industry and the Space boosters Industry it was all the same. First the Design Bureau's were producing military rockets and later, whenever possible, re-configuring this "product" into Space boosters. That's what happened with Korolyov's R-7 the most famous and best Russian ICBM; Chelomey's UR-100 and UR-500, Yangel's R-16 (SS-7 or Suddler) which, with some modifications finally "produced" a Space booster "Tsiklon" in the 80's.
Which brings us to our story about the R-16 ICBM.
Yangel's Design Bureau, which separated from Korolyov's OKB-1 in 1954, was at the end of the 50's in a most favorable position. It's R-12 ICBM was already accepted as one of the standard rockets for the Army and was considered much easier to exploit when compared to Korolyov's R-5. Besides, two other main "competitors" were not keeping up. Korolyov's new ICBM R-9 tests and Chelomey's UR-100 tests were delayed due to various technical reasons, while Yangel was already "delivering" his new R-14 and R-16.
Another reason for Yangel's favorable position with the military in comparison with Korolyov and Chelomey, was that Yangel was very good with interpersonal politic always very attentive to any complaints in connection with his rockets design. Not only was he attentive but also his Bureau adjusted their missiles to the requirements of the Army to make it simple for the service. The other two designers were different "You don't know how missiles work, don't interrupt!" would be a more expected response from them!
The third reason for Yangel's favorable position was his close ties with Glushko, the main and foremost designer of Soviet rocket engines. Glushko's Bureau designed and built all the engines for Yangel's missiles and boosters. Most of these engines used very toxic fuel which became yet another source of conflict between Korolyov and Glushko, because Korolyov was always reluctant to use toxic fuel to power his boosters and missiles.
By the beginning of October 1960, Yangel reported to his main "customer" Commander-in-Chief of Strategic Missile Forces General Nedelin that he would be ready to test a new ICBM R-16 in November. By then, a pad for Yangel's missiles would be constructed at Baikonur pad #41. All previous missiles had been previously tested at Kapustin Yar.
Having good relations with Yangel and promoting him in front of the Politburo, Nedelin made a decision to conduct the first R-16 test on the eve of The Great October Revolution Anniversary (November 7) perhaps the most important and prestigious day in any year. But there were lots of technical problems. As Chairman of The State Commission for the R-16 test if needed, Nedelin's authority would help to resolve any issues that might arise.
There were also a lot of top military and designers at the pad during the preparation for the launch. This was a very big and important event. It had to go and go well!
The R-16 ICBM engines used very toxic, inflammable fuel with one main component nitric acid. The service team at Baikonur had no experience with such fuel and was working without proper precautions.
The missile was fueled October 23rd, but after several systems' check-ups it was found that there were various problems in the electrical connections and targeting system. Nevertheless there Nedelin made a decision to solve all the problems at hand on the already FUELED MISSILE. A decision so risky it is- today and in hindsight unimaginable.
Because of the nitric acid fuel component there was only one chance to launch the missile during a 'window' of no more than 30 hours. If the problems were not solved by that time fuel had to be poured off and the next attempt for the launch if all other problems were solved could be no sooner than 6-8 days later.
This scenario would have them miss the prestigious November 7th launch date when the eyes of the entire Soviet Union would be turned and watching them! Failure was not an option!
Within the next day, problems were falling like apples from a tree one after the other. It no longer mattered that there was only 50/50 chance that one or another system would work the "approved" stamp started appearing on the papers that cleared the work being done. This mission now had a new and unofficial status RUSH!
Nedelin and many other top designers were very close to the missile on the pad to demonstrate to the officers and soldiers not their bravery but to show that everything was proceeding as usual and standard. They also made it clear that they were available to solve any problems on the spot. Nedelin even asked for a chair and was sitting 40 meters (appx 120 ft) from the missile. (Breathing the evaporation of nitric acid! Was he stupid? No he was known as a very brave person, completely dedicated to his service and even responsible for the Soviet "Nuclear Shield").
The time for the launch was expiring; they had until 6 p.m just a few hours left. Service and test teams had already worked for 3 days without the proper sleep. At that time (many people presume that on Yangel permission) officers from the Command bunker switched off many key electrical blocking systems including the system, which allowed the automatic ignition of the 2nd stage. (In a "normal" test situation, it was good if after the launch anything goes wrong with 1t and 2-d stage separation 2nd stage will ignites automatically in due time, "push out" 1st Stage and the flight will go OK).
At last, the 1-hour count down preparations was under way. There were around 250 people on the launch pad. Normally there could never be more than 100. General Mrikin, Deputy Commander of Baikonur, suggested that he and Yangel go for a smoke both were heavy smokers. Because of the toxic and highly flammable fuel they went several hundred meters from the pad, behind a bunker. They still had 15 30 minutes before they would have to take shelter in this same bunker, during launch.
Then, at 6.45 p.m. local time, suddenly and without warning, the engines of the 2d stage started to ignite (the blocking system had been switched off) and initiated the firing of the 1st stage. Additionally, due to evaporation of highly combustible vapors, the pad and missile were completely engulfed in the fire within a few seconds. It was a searing hot wild fire fed by 160 tons of fuel and nitric acid. There was no possibility of escape for anybody closer than 100 meters. Most were much much closer than that...
The incredible explosion instantly killed 126 people, including General Nedelin, Chief Designer Konoplev, two of Yangel's deputies, and Glishko's deputy. 50 persons died later in the hospital.
Later, Khrushchev met Yangel with the question: "Why you are alive?"
It was biggest "missile" catastrophe ever, not only in the USSR, but also in the World.