According to information posted by the US side, the ship CSB 8021 has been renovated and tested by the US side, handed over to the Vietnamese side, and set off to return home. Before handing over to the Vietnam Coast Guard, the ship CSB 8021 was completely repainted by the US side with Vietnam’s national emblem and flag; and especially, the US side removed some weapons from the ship. One of the weapons that was removed from the ship by the US, was the high-speed Phalanx artillery batteries used for close-range defense. The Phalanx short-range defensive high-speed artillery system, considered the standard weapon, appears on nearly every American warship. Born in the 80s of the last century, Phalanx high-speed cannon is designed to be able to fire automatically, its target is objects flying at close range, including aircraft, cruise missiles, … of the opponent. The strength of this weapon is that it has an automatic control mechanism, can use pre-installed radar, to follow the target and fire itself, the firing rate of the Phalanx high-speed cannon is up to 4500 rounds. /min – equivalent to about 75 tablets/second. Also one of the very powerful weapons, however, the US side did not remove the OTO Melara 76mm cannon from the CSB 8021 ship before handing it over to Vietnam. Designed by Italy in the 60s of the last century, the 76mm OTO gunboat is still commonly used on many small American and Western warships. One of the most “expensive” features of this gunboat is that it has an extremely fast rate of fire, up to a maximum of 85 rounds per minute – that is, firing twice every 3 seconds. In addition to the fast rate of fire, the OTO 76mm gunboat also has an extremely advanced cannon stabilization mechanism, which allows to accurately fire the target at a distance of over 10 km. The range of this cannon, depending on the type of ammunition, will be able to shoot up to 16 km to a maximum of 40 km with the most modern Vulcano version. For a fast rate of fire of up to 85 rounds per minute, all incoming OTO 76mm ammunition is housed in a rotating magazine with an electrically automatic reloading mechanism. Theoretically, this automatic magazine can hold up to 80 rounds – that is, with the maximum rate of fire, the 76mm Melara cannon can fire all the ammunition in the magazine in less than time. 1 minute. To ensure the ability to operate at high intensity, the OTO 76mm naval gun has a liquid-cooled mechanism, avoiding the temperature of the barrel and the firing mechanism being pushed up too high. This cooling system can use seawater or fresh water depending on different settings. Close-up of automatic ammunition of the OTO Melara 76mm cannon. Image source: USnavy. The “horrifying” rate of fire of the 76mm OTO Melara cannon on the American battleship Source: USnavy.

NW 2501 before the disaster and Captain Lind.

1. The story begins on Friday night, June 23, 1950 at La Guardia Airport, New York, USA. The weather was warm when 55 passengers, including 27 women, 22 men and 6 children, boarded a DC-4 4-turboprop aircraft, number 2501 of Northwest Airlines, from New York to Seattle (state Washington). Estimated flight time is 6 hours at 660km / h.

At 19:30, the 2501 took off. The captain of this flight is Robert C. Lind, the first co-pilot is Verne F. Wolfe, both 35 years old, and the third and last person in the crew is flight attendant Bonnie Ann Feldman, 25 years old. .

Passing Cleveland, Ohio, the 2501 continues to fly to Minneapolis, Minnesota at 3,000 meters. As she prepared to approach the city airspace of Battle Creek, Michigan at 22:41, the Chicago Air Traffic Control Center ordered Captain Lind to lower the altitude to 2,500m to avoid another plane flying in the direction. opposite.

At 11:36, the 2501 reached Lake Michigan. Upon receiving news from the Chicago Air Traffic Control Center that a storm was forming on the lake, Captain Lind asked to lower the altitude to 1,500 meters but was rejected because at such a height, the plane could will not stand the gust of wind.

At 11:51 p.m., the 2501 entered the fringes of a storm that was growing stronger. Captain Lind reported via radio that the plane would arrive in Milwaukee before 0:30 a.m. on June 24. About 10 minutes later, Lind once again asked to lower the altitude to 1,000m but did not give specific reason. The Chicago Air Traffic Control Center’s answer was still: “No way!”

That was Captain Lind’s last contact with the ground. On the other side of Lake Michigan, the Milwaukee Air Traffic Control Station, after waiting until 1 in the morning, still did not see the 2501 radio signal to New York, Minneapolis and Chicago. Immediately, the Civil Aviation Administration’s radio stations attempted to communicate with 2501 on all frequencies but to no avail. Flight 2501 is missing!

2.5:30 a.m. on Saturday, June 24, the US Civil Aviation Administration officially announced the complete loss of contact with the 2501. They also said that the amount of fuel on the plane was completely exhausted by that time so it could no longer fly, and issued an emergency search order to the navy, the coast guard and the state police from Illinois to Michigan, Wisconsin and Indiana. Thirteen hours later, at 6:30 p.m. on Saturday, the Coast Guard ship commanded by Captain Woodbine saw an oil slick and some debris allegedly from a 2501, floating on the surface of Lake Michigan. At 5:30 a.m. on Sunday, June 25, the sonar machine of the US Navy ship led by Captain Daniel Joy was near the oil spill, and found some objects that reflected very strong sonar waves. However, scuba diving conducted by a naval clone showed that it was not the wreck of the plane, but that of a shipwreck.

Also on Sunday, the Coast Guard fleet consisting of four ships led by Woodbine, Mackinaw, Hollyhock and Frederick Lee recovered many floating debris, including fuel tank fragments, seat pads, clothing pieces. , blankets, luggage and some parts of the corpse but not a single piece of debris was large enough to confirm it fell from the 2501. Investigators speculate that the 2501 exploded in the sky because of their followers. The aircraft twisted when it fell into a gust of wind, causing a spark to burn the fuel tank. Prosecutor Berrien Louis Kerlikowski and US Coast Guard officials said: “It must be a terrible explosion to tear the passenger body in an unimaginable way.” However, residents of Lake Michigan said that on the night of June 23 and 24, they heard no explosions except for the testimony of a retired naval lieutenant, RT Helm.

According to Mr. Helm, he saw an airplane passing through his house at 12:20 a.m. and then a flash of light accompanied by a terrifying explosion. However, compared to Captain Lind’s last contact at 0:01 when he requested to lower the altitude to 1,000 meters and the speed of the plane, by 0: 20 minutes, the 2501 had passed out of Lake Michigan and is in Milwaukee airspace. The divers’ search during the following days was also fruitless, partly because the bottom of Lake Michogan was muddy, and the visibility was limited. In addition, many of the large objects detected by the sonar are not those of the 2501.

In July, a local fisherman, Wallace Chambers, pulled the net onto a small, distorted piece of metal. Analysis of the US Civil Aviation Commission led to suspicion that this piece of metal belonged to the 2501, but during World War II, the US military used more than 3,000 DC-4s and by the end of the war, nearly 600 the aircraft became a civil aircraft with identical construction, so the wreckage recovered by Wallace Chambers said nothing.

Six months after the disappearance of Flight 2501, after thoroughly analyzing all the collected specimens, the US Civil Aviation Commission officially concluded this was a “catastrophe without any cause”.

From there, over time, the incident sank into oblivion until science invented advanced detectors, which could restore the model of the seabed, river, lake, with all the details in on the bottom the search for the 2501 begins to restart.

DRAW HIGH