The DC-3 (Tp 79 Hugin with Air Force Number 79001) at F 8 Barkarby. Photo: Herman Allwin (kristianstadsbladet.se) [Public domain], via Wikimedia Commons

The spy plane that disappeared

Friday, June 13, 1952, a DC-3 takes off from Bromma airport. On board are eight people on a top secret operation. The plane never returns and remains gone for over 50 years.

In the morning, the Swedish Air Force’s Tp 79 with flight no. 79001 disappears leaving only liferaft shot into pieces.

Tp 79 is a variant of the Douglas DC-3A-360 Skytrain used for military transport. The press reffered to it as the DC-3.

Two hours after they departed from Bromma Airport, on their way home from a radar mission, the radio contact with the plane is lost. A major rescue operation is being launched quickly, but only a liferaft with splinter from Soviet ammunition is found. The DC-3 had disappeared without a trace.

The story of the DC-3 summarizes in many ways Sweden’s history during the Cold War. It was a period when the world was in a state where neither war nor peace existed, and where the tensions between East and West still were present. It is also the story of secrets, superpower politics and complete silence to the crew’s relatives.

Background

In the early 1950s, the Soviet airspace was subjected to constant violations. In the first hand of British and American aircrafts, but also by Swedish. The DC-3’s routes were mostly outside Swedish radar coverage. The crew knew that the plane was followed by Soviet radars. That was the meaning. The Swedish Air Force deliberately took great risks with the tension against the Soviet Union. One of the tasks was to get acquainted with how they answered the provocations.

The Soviet Union’s military leadership knew about the operations of the DC-3, and writes in a report from June 1952: “The purpose of the flights is clearly obviously against our radar systems in the Baltic States.”

In the first Swedish press releases about the disappearance of the DC-3, there is no mention of the suspicion that the aircraft had been shot down, inter alia to conceal the fact that the air force together with the Defense Radio Department (FRA) operated signal intelligenxe. Representatives from the air force and the Swedish government claimed that the crew had been on an innocent navigation training. The Swedish press ingested a hard anti-Soviet line.

Three years before the shoot-down of the DC-3, contrary to the official strict neutrality line, Sweden entered into a secret agreement with the United States and the United Kingdom. Swedish signal intelligence data were to be exchanged with US technical equipment. The Air Force’s specially equipped TP 79s 79001 «Hugin» and 79002 «Munin» conducted on a regular basis top secret flights across the Baltic Sea with US signal intelligence equipment on board. Sweden also undertook photo intelligence against the Soviet Union. In 1948, an S 26 Mustang flown by Fredrik Lambert-Meuller deliberately violated Soviet territory. The plane was equipped with a camera lent from the US Air Force. In 1949, the flight flights continued with an S31 Spitfire, which were flown by Ingemar Wängström.

The main objective of the operations was to obtain information about the Soviet Union’s air defense, especially its capabilities to combat US Boeing B-47 Stratojet bombers equipped with nuclear weapons.

The assignment

Signal intelligence was a dominant part of the top secret intelligence business that was developed during World War II. It was about obtaining information, for example, by capturing encrypted morse coded messenges. Signal intelligence was considered to be an important part of the Swedish defense’s preparations for a possible Soviet attack. The Swedish Defense had modern equipment and well trained personnel for this type of operations.

Since the 1950s, FRA has dedicated itself to advanced technical signal intelligence intercepting signals from, for example, Soviet radar systems. Technical signal intelligence also occurred from onshore stations, but by placing equipment on an aircraft they reach beyond Soviet territory. Mapping and evaluating these Soviet systems was a very important part of Sweden’s defense work.

Their assignment was primarily to find and identify new signal sources in the radar and battlefield management systems that the Soviet Union were building along the Baltic coast.

Despite the fact that the flights were conducted in international airspace, they were provocative of Soviet leadership. The then chief of FRA reported that the crew was influenced by the tense on the Swedish-Soviet relationship and began to feel a unease for the assignment.

On the morning of 13 June, the Swedish Air Force’s DC-3 with number 79001 prepared for it’s 27th flight of the year. They headed east to gain further knowledge of the Soviet Union’s technical development, war and defense capacity, using their advanced equipment. The flight was scheduled to take 3.5 hours. The route usually went north-south, west of the midline between Swedish and Soviet territory.

Their main assignemnt was undoubtedly technical signal intelligence. But until 1983, everyone with knowlede to assignement insisted that the crew had performed navigation training. The crew’s families did not get any other explanation, even though they knew their relatives worked on secret assignments.

Between 9 and 20 June 1952, the Soviet Union carried out a major naval exercise in the Baltic Sea. The new missile cruiser “Sverdlov” was under test and in Liepaja on the Baltic coast there was a newly built radar station. More than 40 vessels, including a large number of submarines, participated in the exercise.

Model of the DC-3. Photo: Pål Stagnes

The plane before it was shot down

The aircraft was built in 1943. Its original US serial number was 42-5694. The plane was delivered to the USAAF 15th Troop Carrier Squadron (61st Troop Carrier Group).
It was stationed at the RAF Barkston Heath in North Africa. On February 5, 1946, it was flewn from Orly Air Base via Hanau Army Airfild to Bromma. On May 18, 1946, it was registered as SE-APZ a civil aircraft belonging to Scandinavian Aero AB.

A model of the DC-3, TP 79001, with equipment and crew as it was equipped on its last flight on June 13, 1952, is exhibited in the Air Force Museum in Linköping. The flights were extremely secret so drawings of the plane and information about exact location of the equipment have been difficult to obtain. The model makers have created the model based on information from experts and veterans from FRA, and the Air Force has been able to provide facts from the Armed Forces Technical Report from the TP 79001 accident.

The crew

On board were eight crew members, three from the air force and five from FRA. In the cockpit was pilot and commander Alvar Älmeberg and technician Herbert Mattson. Navigator and radio-communicator were Gösta Blad. The five signal intelligence officers (sigint) from FRA were group-chief and sigint officer Einar Jonsson together with the sigint officers Ivar Svensson, Börge Nilsson, Erik Carlsson and Bengt Book. They had their workstations in the cabin.

Alvar Älmeberg, Gösta Blad, Einar Jonsson and Herbert Mattsson has all been found and identified.
Bengt Book, Börge Nilsson, Erik Carlsson and Ivar Svensson are still missing.
The wings

A DC-3-wing consists of three parts; Right, left and middle wing. The entire flight body is mounted on the sturdy mid wing, where also fuel tanks, motors and landing gear are mounted. When the DC-3 hit the water it was exposed to huge forces. This can be seen, for example, by the midwing has turnedcounterclockwise; Left side back and right side forward.

At each operator’s workstation there were a number of equipment for signal intelligence. Photo: Pål Stagnes
The equipment

At each operator’s workstation there were a number of equipment for signal intelligence. Receivers and recorders were used to find signals, intercept them and record it. Three of the operator workstations were used for technical signal intelligence, ie monitoring radar stations and other technical signals. One of the stations was set up with communication equipment for the interception of radio traffic and telegraph transmissions. At the far back of the right side of the cabin, the group-chief had his workstation. His equipment was used for technical signal intelligence.

Antennas and radios

The DC-3 was modified to be equipped with different types of receivers and antennas, depending on the type of assignment to be performed. Most antennas on the DC-3 were designed to receive signals regardless of direction. Some antennas were mounted in protective dome-shaped radomes, two on the upper side of the body and two on the underside of mid-wing. These antennas were angled forward and gave best results if the plane fled directly to towards signal source. In a radome under the flight body there was a directive antenna that could be controlled to point in the desired direction.

The shoot down

In the Soviet Union, the annoyance was great over Sweden’s secret cooperation with the United States and the United Kingdom, and there were plans to attack the DC-3. On the morning of June 13, 1952, on a flight base near Riga, the pilot Osjinskij were seated in a MiG-15. It was a fast fighter plane equipped with extra tanks and sharp ammunition. On order from General Sjinkarenko, Osjinskij took up the pursuit of the DC-3. He quickly approached the target and awaited attack orders. At 1123, the attack starts and 160 23-millimeters and 27 37-millimeters projectiles are fired. The DC-3 is hit by several grenades, and at least one of them hits the left oil tank, or near the tank. A strong fire occurs and the burning DC-3 crashes and the radio transmission from the aircraft were interrupted.

On the left wing and on the left side of the aircraft body, the aircraft has clear fire damages.

The crew that were seated in the rear of the plane was badly affected by the shooting, but splints also reached the cockpit. Probably several of the crew was hit by splints.

The wreck of the missing DC-3. Photo: Pål Stagnes

The crash

There were a risk that the fire could break of the left wing, leaving the plane crashing uncontrollably. It is likely that the DC-3 pilot Alvar Älmeberg attempted to make an emergency landing on the sea. According to the airplane, which has been salvaged, the plane crashed with the sea at 1128, five minutes after it was hit.

The DC-3 hit the water with such force that both engines with propellers were torn from their parties. The cockpit was broken and the left wing torn of. The left side of the body was flared up from the cockpit to the rear luggage compartment door. Most of the equipment in the cabin were thrown out.

The Catalina plane that wereshot down. Photo Pressens Bild (dn.se) [Public domain], via Wikimedia Commons.

The rescue operation

The onshore station at Roslagen’s airline F2 called the DC-3 without a response and a comprehensive rescue operation were started. In the search two Catalinas, fifteen radar-equipped aircrafts and seven vessels from the Navy were included. Only two hours after the DC-3 disappeared, a Catalina reached the assumed crash site. The search was made difficult due to low clouds and poor visibility. The wrecks were not found.

Three days later, two Swedish military naval aircraft of the type Tp 47 (Catalina) participate in the search for the DC-3. The search was abruptly interrupted when one of the Catalan were fired upon by a Soviet fighter. The plane were forced to do an emergency landing on water near the West German freighter «Münsterland». All five crew members from the plane were saved.

The aftermath

The Soviets demented all knowledge of the shooting down of the DC-3, despite the fact that a lifeboat from the plane was found a few days after the shooting. The lifeboat had splints from ammunition from an MiG-15.

In 1956, Soviet leader Nikita Chrutstjov met the Swedish Prime Minister Tage Erlander. Chrutstjov acknowledges that it was a Soviet fighter who had shot down the DC-3. This information were kept secret.

Firstly in 1991, Russia officially admitted that the plane had been shot down by a Soviet fighter jet of the MiG-15 type. In the Russian publication, which was approved by President Boris Yeltsin, it was said that the DC-3 had not violated Soviet territory.

On the other hand, the DC-3 was nearing the new Soviet marine vessel «Sverdlov», expected to take pictures and try to locate the vessels new radar view. This appears in a secret FRA document found in the War Archives.

The Soviet motivation for the shooting was probably that the DC-3’s were perfoming signal intelligence on behalf of  the British GCHQ and the US NSA, and partly that it was a direct military threat to «Sverdlov». It came too close with cameras and other equipment and thus became a direct threat.

After pressure from the relatives’ families, the Swedish authorities confirmed that the DC-3 was equipped with British equipment and had spied for NATO. The first official confirmation from the government came in 1983 after the book «Flygaren som försvann» (the pilot that disappeared) had been published.

The fate of the aircraft remained a secret until November 1991 when General Sjinkarenko then admitted that he had given the orders to the shoot down in June 1952.

There were people in Sweden who knew more than they revealed. The assignments of the DC-3, capacity and the assignment’s link to NATO countries were sensitive and top secret and they continued to be so. The crew’s relatives were met with silence. They could only wait. This gave rise to rumors and speculations. Had the plane been salvaged by Soviet military? Had some of the crew survived? Had they all been taken prisoner? Would they ever come home again?

Photo: Pål Stagnes

Secret collaboration

Other states also saw the benefit of increased knowledge of the Soviet Union’s air defense. Under the highest secrecy, and contrary to Sweden’s neutrality line, collaboration with the United Kingdom and the United States were ongoing, thus refraining them its own intelligence.

After the DC-3 was shot down in June 1952, the collaboration between Sweden, the United States and the UK became even closer. The development of fighters, radar systems, missiles and exchange of intelligence continued in such a way that the cooperation became close to NATO – each country promised to defend the others.

The search

Previous attempts to find the DC-3 had all been unsuccessful. Pilot Anders Jallai had been interested in the fate of the aircraft for several years and in 2000 he, together with historian Carl Douglas and Ola Oskarsson from Marin Mättaknik, took the initiative for new searches. Jallai led the project, funded by Douglas and Oskarsson.

Among the challenges they had to overcome was that there was no confirmed crash site nor any concrete traces. Large areas had already been searched without results. The information found and which could have been helpful was often misleading. The group’s first search expeditions, conducted in 2000 and 20002, was both unsuccessful.

Before the search in 2003, questions were rised about the previous searches. The search team decided to ignore all previously known information and start over. Any conceivable place should be examined carefully before it could be ruled out.

After a few weeks of searching, they encountered something that could be the DC-3. The finding proved to be a Russian submarine from the First World War.

Despite the adversity, the crew aboard the vessel «MS Triad» continued to search. On June 10, 2003, after 47 days of search, the DC-3 was found at 126 meters deep northeast of Gotska Sandön.

 

The Swedish crown marks’ colors have been changed. Photo: Pål Stagnes

The time on the seabed

52 years on the seabed have set its mark. The dark, cold and oxygen-poor environment at 126-meters depth has caused some materials to be preserved, while others have almost disappeared. The hull has major corrosion damages and the colors of the Swedish crown mark has changed. The former yellow parts have now become dark and the blue have become bright.
When the aircraft returned to the surface and became exposed to oxygen, the decomposition was accelerated. To stop this, all parts had to be cleaned and then treated with a rust protector.

The wreck of the missing DC-3. Photo: Pål Stagnes

The salvage operation

When the missing DC-3 was found at the bottom of the Baltic Sea in 2003, the Swedish government decided that the aircraft should be salvaged. The goal was to find the remains of the eight crew members.

The salvage operation was complicated, one of the hardest the navy ever done. The storage vessel «HMS Belos» was responsible for the operation. Underwater films and sonar images showed that the plane had major damages and was therefore very fragile. One risked that both the nose and tail sections were torn apart from the plane’s body.

In order to carry out the salvage as safely as possible, the right wing was sawn off, and the body was moved to a lifting basket located next to the aircraft’s body. After a great effort, the basket could be lifted out of the water just after midnight on March 19, 2004. The DC-3 was transported to Muskö naval base.

Remains, wrecks and objects lay scattered on the sea floor in an area of approximately 600 meters radius from the wreck. It is estimated that 90-95 percent of the wreck is salvaged. It was possible to identify and salavge even small objects.

Besides items from the plane personal belongings such as wallets, keys, glasses and a wedding ring were also salvaged.

The hull of the aircraft today has many damages. Most caused by corrosion from the years the plane lay at the bottom of the Baltic Sea. Corrosion damages are many cases difficult to distinguish from the holes caused by shrapnel. The hits from the grenades seem like quite large holes where the plates are bent inwards around the holes.

The cockpit

Of the DC-3’s characteristic nose, almost nothing remains. From the windows and down, everything has been broken and virtually everything in front of the control panels is gone. The right side of the cockpit has been blown out, while the left side is strongly impressed.

Engines and propellers

During the salvage of the wreck, the aircraft’s engines and propellers were found far from the planes body. The right engine and propeller were approximately 200 meters south of the aircraft body, while the left engine and propeller were found 70 meters northeast of the wreck.

On the left propeller there are strong chopper in the propeller blade. Probably these originate from the propeller having cut into the door behind the cockpit. Another propeller blade shows traces of shrapnel. The curved propeller blades show the huge power DC-3 hit the water.

The curved propeller blades. Photo: Pål Stagnes

Those who still are missing

Pilot and commander Alvar Älmeberg, sigint officer Gösta Blad, group-chief Einar Jonsson and technician Herbert Mattsson were found and identified when the aircraft was found.

Still four of the crew members, Bengt Book, Börge Nilsson, Erik Carlsson and Ivar Svensson, have not been found, despite the fact that a few hundred meters around the wreckage, east of Gotska Sandön, have been investigated.

The Swedish security police, Säpo, had through their sources information that there could have been a ninth man on board. The nationality of the man was unknown. The same sources indicated that the DC-3 operated against the ongoing Soviet naval exercise together with a foreign state. Officially, the crew consisted of eight men, all Swedes.

According to the accident report, the damage on the seats indicated that the crew were seated when the plane crashed.

There are theories that they can have be rescued up by a Russian torpedo boat and led to Tallinn to be handed over to Soviet authorities. In the early 1980s one of the widows received a postcard from Leningrad, which she assumed was from her husband. Even prisoners from Gulag have witnessed that four Swedes were inprisoned inVorkuta and Norilsk camps, but the information is uncertain. What we know today is that Soviet vessels were in the area and probably were first at the accident site. This isaccording to the accident investigation.

The the newspaper Expressen, Christer Magnusson, Chancellor of Investigations, in 2004 said that the handle on one emergency exit was opened and the stick was withdrawn. This could be because someone tried to open the emergency exit.

Another explanation is that the handle was opened when the plane hit the water. «Maybe we will never know the answer», Christer Magnusson said.

What speaks against the crew to be seated at the time the planed crashed are several Soviet documents from 1952 saying that at least one person left the plane in a parachute. Several experts believe that the documents have high credibility.

All Soviet documents are based on the Soviet pilot Osjinskij’s statements. He reported that the crew jumped. Other Soviet pilots have also mentioned parachutists.

After the Soviet Union acknowledged the shooting in 1991, the pilot denied that he had seen anyone leave the plane in parachutes. In the accident report there are no traces of triggered parachutes. On the other hand, all who were found wearing life jackets.

The four who are still missing were employed by FRA. They were on sigint officers and listened to Soviet radar and radio transmission.

The FRA sigint officers Bengt Book, Eric Carlsson, Börge Nilsson and Ivar Svensson were seated in the front of the plane and the analysis of shrapnel shows that they can have managed without major injuries.

It had been logical that the FRA men jumped first, while the pilots tried to keep the plane in the air.

«According to the list of materials on board, there are four life jackets and at least four parachutes missing», said ChristerMagnusson, according to SvD.

Sunday, June 13, 2004, on the 52th anniversary of the disappearance of the DC-3, a memorial ceremony was held at Berga’s war school. Together with the commander and other representatives, Leni Björklund, Anders Jallai, Carl Douglas and Ola Oskarsson, who found the plane in 2003 and relatives of the crew. During the ceremony, the crew was awarded the defense’s medal of gold.

Air Force Museum (Flygvapenmuseum). Photo: Pål Stagnes

Air Force Museum

The salvaged DC-3 is exhibited at the Air Force Museum in Linköping, where a whole department is used to tell about the plane and the cold war. In the museum you can experience the Swedish military flight development, from its birth up to today’s JAS 39 Gripen.

The museum is a modern technology and cultural history museum reflecting the development of Swedish military aircrafts from the pioneer period up to today.

http://www.flygvapenmuseum.se/languages/engelska