I've heard that a lot has been written about the airbase near Bihać in L+K, but I bring you details taken from the text of the forum of former ex-Yugoslav countries and directly from people who served at this airport and who spent a part of their whole lives there.
The year is 1957. In strict secrecy, the first silhouettes of the secret "505" facility are taking shape at the Ministry of Defence in Belgrade. Specifically, in the Special Purpose Building Department. The chief engineer of the project is Colonel Dr. Lj. Kodelja and Colonel V. Smirnov. Even before that, the territory is selected. The choice fell on a place which is close to the city of Bihac, in the centre of the former Yugoslavia, and which is covered on almost all sides by high mountains.
It was not until 1959 that the first fieldwork began. The work was entrusted to the state construction company "Soča". At the same time as the construction of the airport, the tunnels themselves, 5 large runways were being built for the landing and departure of aircraft. However, here the first problem arose, because the mountain massif in which the airport was to be located was made of very hard rock and blasting methods had to be used all the time. The engineers therefore used the blasting methods of "full and empty fill" and achieved almost centimetre accuracy in digging a tunnel 20 m wide, 8 m high and 1 km long. The end of the excavation dates back to 1965. The work was carried out in secrecy in three shifts and around 250 technicians and engineers were employed. It was only in 1966 that the first units of the Yugoslav air force began to arrive.
The military airfield they made looked really impressive. There were 3 tunnels plus one reserve tunnel (escape tunnel), which connected at a "junction", behind which led a giant hall where Migs, up to 12 m high, were repaired.
These tunnels were 500 m, 400 m and 350 m long, 20 m wide and 8 m high! This base in the bottom of the Gola Pleševica mountain was also designed to withstand a precise hit by a 20 kt nuclear bomb. Each of the 4 tunnels was twisted and had a concrete curtain on the upper sides every tenth metre. All of this led to reinforced concrete gates that were designed to withstand an impact of up to 3 atmospheres. This impressive gate weighed around 103 tonnes, was 21 metres long, 9 metres high and 1 metre thick. It hermetically sealed off the entire underground airfield and slid sideways.
Otherwise, the building itself in the massif of the mountain was designed to survive in it for a longer period of time with the entire men and crew of the facility, which means that there were missile storage, bombs, complete repair facilities for the Mig-21 type, aviation giant fuel tanks, kitchen, hospital, rooms for the aviation and maintenance personnel of the facility.
In the very centre of the facility, or underground airfield, was an elevator that led almost 30 metres up to the control tower, which was actually a bunker from which all air traffic in the outdoor area of the airfield was controlled. Here was the mission command and planning, radar, weather station and, most importantly, the headquarters of the entire facility.
Since the airfield was designed to survive a nuclear attack, it had its own fuel tanks, but otherwise there was about 20 km of pipeline leading into it, terminating at the Army's fuel depot at the foot of Mount Pokoj. And the ammunition was stored 5 km from the airfield in the village of V. Polje.
The ventilation system of the building itself was a real sensation for its time. It worked continuously and kept the temperature even in the very centre of the Klek facility, i.e. in the core of the mountain, at a constant temperature and low humidity. It was around 21°C in the rooms and 18°C in the aircraft tunnels. As far as water was concerned, when the tunnels were being dug, there was a small river that eventually supplied the facility with water.
The outside part of the airbase consisted of 5 runways: 2 (landing-taking-off) and 3 take-off runways, and barracks and logistics stores.
On the mountain Gola Plješevica itself, i.e. on the mountain in which the Klek facility was hidden, at a height of about 1,650 m, the English radar S-613 was installed, which was the Mercedes among radars for its time, and so it was possible to monitor what was happening in the whole of Italy, Hungary, Austria, which caused great opposition from these countries. I remind you that the range of the radar at that time was some 400-450 km! The radar itself had its part of the staff buried near it and in winter it was only possible to access this hill by helicopter because of the height and the snow. Only the radar survived until 1995, after which it was destroyed by the Croatian army.
In terms of personnel, the 117th Air Fighter Regiment with Mig-21PF aircraft and the 323rd Reconnaissance Regiment with Mig-21R aircraft were stationed at the airfield.
The only similar facility is the Slatina airfield, which is much smaller.
The cost of this facility, that is, the entire airport, both the outdoor infrastructure and the facility in the mountain itself, cost a whopping $4 billion for its time! And certainly a lot of lives, as there are rumors of political prisoners and death row inmates who were sent there and never returned.(Witnesses who saw the black patched buses go by are still alive today.)
In 1992, as almost all of Yugoslavia was already torn by war, Serbian troops destroyed this airport. That is, the army that had been taking care of this airport and covering it as its most secret airport on May 12, 1992. With the help of a few trucks, they destroyed the tunnel entrances and the runways and bombed the parts that could be used.
Thus ended the 4 billion dollar fairy tale of a facility that was something of a science fiction story for its time. Something so technologically advanced and ingenious.
Excuse my Czech, I don't live in the Czech Republic, but I know some of your language, I don't have commas on my keyboard either
If anyone appreciates my efforts and is interested, here is a link to some interesting videos of what it used to look like...
I think it's worth a look...
www.avijacijabezgranica.com
Vjezd do tunelu č.2 .Fotka je z roku 2002-05 Je videt krasne zaclona proti uderu n. bomby ve tvaru profilu Mig 21