Crash C-54 in Alvarado

The Douglas C-54G-10-DO Skymaster involved in the incident with registration number N88942 (serial number 36076) was released in the second half of 1945 and entered the customer on October 9, the U.S. Air Force , where it initially received tail number 45-0623. However, ordered back during World War II , this transport aircraft was not needed in peacetime, since the army was oversaturated by them. Therefore, in 1946, this C-54 was bought at almost the price of scrap by the American civilian airline Pan American World Airways (Pan Am), where the aircraft receives registration number N88942 and the name Clipper Bostonian . But after a few years, an excess of these aircraft formed in Pan Am, so in 1951 the N88942 was leased by another American airline, Transocean Air Lines (callsign - TALOA ), which at that time was one of the largest charter air carriers in the country, mainly performing military operations in connection with the Korean War at that time ^{[1] [2] [3]} .

The operating time of the N88942 was 5976 flight hours since the last major overhaul. Had four piston engines Pratt & Whitney R-2000-4 equipped with Hamilton Standard propellers ^[4] .

In the cockpit were three pilots ^{[5] [6]} :

• Instructor Pilot - 41-year-old Harvey W. Rodgers - Chief Airline pilot. In Transocean Air Lines since March 16, 1946; had a total flight time of 8312 hours, including 5570 hours on type DC-4 / C-54.
• The aircraft commander is 41-year-old Herman E. Hum. In Transocean Air Lines since August 23, 1946; had a total flight time of 10,656 hours, including 7,379 hours on type DC-4 / C-54.
• The co - pilot is the 37-year-old Frederick W. Pachett ( born Frederick W. Patchett ). In Transocean Air Lines since September 17, 1947; had a total flight time of 2886 hours, including 1782 hours on type DC-4 / C-54.

Two stewardesses worked in the cabin ^{[5] [6]} :

• 27-year-old Velma I. Sandridge. At Transocean Air Lines since August 22, 1952.
• 41-year-old Lucille Munro Chapman . At Transocean Air Lines since March 20, 1953.

The aircraft was chartered by the U.S. Department of Defense to transport a group of military pilots and operated a TOA-942 ( TALOA 942 ) passenger flight from Roswell ( New Mexico ) to Guam with an intermediate landing in Auckland ( California ) and Honolulu (the Territory of Hawaii ). According to the flight plan submitted by the crew, from Roswell to Auckland, a visual flight with a minimum height above the clouds of 500 feet (150 m ) (“500 from above”) was to be performed, and the route was as follows: along the Red 88 air corridor to Albuquerque , Green 4 ”to Palmdale ,“ Blue 14 ”and“ Amber 1 ”to Bakersfield , then“ Amber 1 ”to Fresno , and finally“ Blue 10 ”to Auckland. In total, there were 30 military passengers and 5 crew members on board, and the fuel supply was 10 hours with an estimated flight duration of 6 hours 35 minutes. The total weight of the airliner was estimated at 63,817 pounds (28,947 kg) with a maximum allowable 73,000 pounds (33,110 kg); the alignment was also within the established limits ^[7] .

At 12:11 MST, flight 942 flew to Auckland. The flight took place in normal mode, and at 14:51 MST , flying near Winslow ( Arizona ), the crew abandoned the visual flight, switching to instrument flight , while maintaining a height of no lower than 500 feet above the clouds ^[7] .

At 17:32 PST , they reported from Fresno at 17:30 that they traveled 8000 feet (2400 m ), not less than 500 feet (150 m ) above the clouds, and Los Banos was in expect to go at 17:40. At 5:44 p.m. PST, the crew contacted the radio station in Fresno and additionally requested permission to decrease, reporting that following the “500 from above” rule could drop to 7,000 feet (2,100 m ). At 5:47 p.m., the dispatcher issued the following permission: The dispatcher permits Transocean 942 [follow] to the Newark radio beacon keeping 8000 feet (2400 m ). Link to Auckland Approach after Evergreen; no delay is expected. Report a height of 8000 feet ^[7] .

Evergreen was completed at 6:09 p.m. PST at the indicated altitude of 8,000 feet, which the crew reported a minute later, in addition to requesting a decrease to the lower echelon. However, he was denied a descent, as the altitude of 7000 feet (2100 m ) at that moment was occupied by another aircraft, and an indication was given that he was still in the waiting area at the 8000-foot level. In this zone, flight 942 was located for a total of 11 minutes ^{[7] [8]} .

At 18:27 PST, the approach manager instructed the crew to start dropping out of the waiting area to pass the Newark beacon at an altitude of 3,500 feet (1,100 m ), while reporting the passage of each 1,000 feet (300 m ). In the sky at that time there was variable cloud cover 1300 feet (400 m ) high and continuous at 1800 feet (550 m ), rain, a south-south-west wind at a speed of 17 miles (27 km ) per hour, visibility 2.5 miles ( 4.0 km ). At 6:30 p.m., the crew reported a descent from 8,000 feet, after which they reported a descent every 1,000 feet. At 18:36, it was reported that the Newark radio beacon passed at an altitude of 3,500 feet, which was the last message from the N88942. A couple of minutes later, at 6:38 p.m. PST , Douglas crashed into a barley field a mile and a half (2½ km) northeast of the town of Alvarado ( Alamida County). All 35 people on board died ^[8] .

Exploring Debris

The airliner crashed into the field at a distance of 3 miles (4.8 km ) from the Newark beacon in the azimuth of 323 ° and one and a half miles northeast of Alvarado; the terrain is approximately 17 feet (5.2 m ) above sea level. The first wingtip crashed into the ground with a roll close to vertical, followed by a nacelle, and then an explosion occurred. The wreckage was scattered in an area 800 ft (240 m ) long and 300 ft (91 m ) wide , with two large parts remaining: the central part of the fuselage with a part of the left plane that lay upside down at a distance of 634 feet (193 m ) from the point the first impact, as well as the adjacent rear, including the tail and tail cone ^[8] . Chassis at the time of impact were removed, flaps set at 15 ° ^[9] .

The fragments found were tried to be restored on the layout, after which they were carefully studied. So it was determined that the destruction occurred upon impact on the ground, and before that there was no violation of the integrity of the structure. None of the fragments showed signs of fatigue cracks, nor signs of fire. There was no evidence of failure or malfunction in the operation of the primary control system ^[8] . The ailerons and rudder collapsed upon impact, but checking their hinges showed that they moved freely without jamming. The right aileron was in a neutral position, but the rudder trimmer was deflected 10 ° to the left. The wing consoles and the lower part of the fuselage completely collapsed, but it was determined that the wing did not separate ^[10] . The check of the tail unit did not reveal any traces of impact by any object ^[10]

The aircraft was equipped with an anti-icing system, but due to significant damage, the operability of this system and whether it was turned on, investigators could not determine ^[10] .

The belts of all three pilots burst upon impact, that is, all three were at their workplaces. In the same condition they found belts in the places of both stewardesses. Several seat belts in the passenger seats were partially damaged in the fire. All carbon dioxide cylinders from the fire system were found in an unused condition. Both cabin heaters collapsed but their inspection showed no signs of external fire or fuel leakage. Instruments in the cockpit partially collapsed, but their readings could be read, including direction indicators and horizons stuck in the far right position. The pressure value on the barometric altimeters was 30.10 inches (765 mm) RT. Art. (actual - 30.09 inches (764 mm)) ^[9] .

The fuel supply in the tanks, according to the sensors, was distributed as follows: No. 1 - 690 pounds (310 kg); No. 2 - 600 pounds (270 kg); No. 3 - 190 pounds (86 kg); No. 4 - 120 pounds (54 kg). Checking the engines did not reveal any malfunctions. All four propellers at the moment of impact on the ground rotated with a nominal frequency ^[9] .

Weather conditions

On the morning of the incident in the southeast of Montana and northeast Wyoming was the center of the cyclone, which was accompanied by cold weather. The cold front moved east and extended from this center to the southwest, crossing northwest Arizona and southeast California. Along the Pacific coast of Oregon and Washington , an occlusion front formed, which moved southeast and was in northeast California at the time of the incident. Due to such weather conditions, light to moderate icing was predicted in Arizona at altitudes from 10,000 feet (3,000 m ) to 11,500 feet (3,500 m ) east of the front and at altitudes from 4,500 feet (1,400 m ) to 6,000 feet ( 1800 m ) - to the west. Moderate turbulence was predicted for all sections of the route, but without difficult weather conditions ^[11] .

According to eyewitness accounts, cloud cover was 1,200-1,300 feet high in the area of ​​the accident, when for the first mile from the scene the plane was first seen following the clouds. He was in a steep right roll and remained in that position until he hit the ground. At the same time, the navigation lights burned, the noise of the engines was even, and no extraneous sounds were heard. About 1,000 feet (300 m ) west-south-west of the point of impact on the ground was a house, a resident of which ran up to the scene and found pieces of ice on the ground, the largest of which were rectangular in shape and up to two inches (5 cm) thick . The fact that this ice was from a crashed plane was proved by the remaining prints of rivets. According to witnesses, before the crash, the plane flew east of this house ^[11] .

The crews of aircraft flying in the area shortly before and after the crash were interviewed. According to the testimony, pilots at altitudes above 5,000 feet (1,500 m ) faced little icing and weak turbulence. One of the crews, 35 minutes after the crash of flight 942, was located at an altitude of 8000 feet (2400 m ) in the vicinity of the Newark radio beacon, and his plane collided with slight turbulence and severe icing, with ice up to three inches (8 cm) in diameter formed on the antenna masts , which began to melt only when, during the descent, a height of 4500 feet (1400 m ) was passed ^[11] .

There was another factor that could play a role in the chronology of the incident — Harvey Rogers was in the cockpit — the airline’s chief pilot who performed a routine route check on this flight. Among the pilots, Rogers was characterized by high severity, including insisting that the crews strictly comply with the rules established by the airline for flights, including a decrease at a vertical speed of no higher than 400 feet (120 m ) per minute, so that passengers would not experience discomfort. The investigators could not establish exactly where Rogers was sitting at the time of the incident, but judging by the inspections he had carried out in the past, he could sit either on the co-pilot's seat or in the folding seat between both pilots ^[11] .

Data Analysis

In general, from Roswell to the Newark beacon, the flight went fine, but the following points are noteworthy. At 17:30, the N88942 board flies Frisco at an altitude of 8000 feet, and at 17:44, that is, after 14 minutes, the crew requests permission to decrease. Since the distance between Frisco and Los Banos is 60 nautical miles (111 km), and the ground speed of the liner was 190 knots (352 km / h), then for 14 minutes it had to fly 44 miles (81.5 km), then there was still Los Los Banos (26.5 km) or 5 minutes of flight. At 5:47 p.m., the dispatcher instructs the crew to follow Newark, maintaining an altitude of 8,000 feet, and after passing Evergreen to communicate with the approach dispatcher in Auckland, while a delay with landing was not expected. Already at 17:49 the crew reports on the passage of Los Banos at the indicated height and the estimated time of passage of Evergreen at 18:08. At this time, the liner flew at a fairly high speed, that is, the pilots seemed to be in a hurry ^[12] .

At 18:10, that is, after Evergreen, they request a decrease from the plane to 7,000 feet without explaining the reason for this request. According to the testimony of the crews of other aircraft, at this altitude, severe icing was observed, which commander Herman Hum could also observe. There was still 21 nautical miles (39 km) to Newark, or about 9 minutes of flight, so the pilot decided to lower slightly, hoping that at a lower altitude the icing would not be so intense. But the decline was forbidden due to another plane. Then, near Newark’s beacon, flight 942 was sent to the waiting area, where it remained for 11 minutes. During this period, the aircraft was in the icing zone, but the crew did not report anything to the ground, as it probably had no problems with piloting ^[12] .

At 18:27, the dispatcher gives instructions on the implementation of the approach to the airport, but from the plane the start of the decline is reported only after 3 minutes ^[12] . According to the forecast, at this altitude the wind was 280 ° 55 knots, that is, oncoming and strong enough, which led to a decrease in ground speed, and therefore the approach to the beacon took longer. Then the plane began to decline, and the crew regularly reported the passage of each 1,000 feet, after which at 18:36 it reported the passage of the Newark radio beacon at an altitude of 3,500 feet. No problems on board were reported in these reports. The reduction itself from 8000 to 3500 feet lasted 6 minutes, that is, the average vertical speed was 750 feet (230 m ) per minute - almost twice as high as indicated in the rules. There is a possibility that the Rogers pilot deliberately kept silent at that time, as he checked the crew, and he wanted to voice this violation after the flight was completed. Then Douglas gets out of control, after which, with a steep right bank, it enters a rapid decline, losing 3,500 feet in a couple of minutes, that is, at a vertical speed of about 1,750 feet (530 m ) per minute, and three miles from the beacon crashes into the ground ^[13] .

It was not clear what caused this loss of control. A version was considered about the failure or malfunction of the aileron control system, but no evidence was found, including the right aileron at the time of the disaster was in a neutral position. The control cables could not be verified due to the destruction of the wing. The position of the flap indicator was somewhat strange, but it could be explained by the influence of a side impact on the ground ^[13] .

The witness pointed to the presence of thick pieces of ice at the place of impact, which, judging by the contours, fell off the plane upon impact. This meant that the airliner could run into severe icing. If the crew knew about icing, then they had to turn on the heating of the air pressure receivers (LDPE). However, if the LDPE heating was not turned on or turned on incorrectly, then ice would begin to form in the pitot tubes, which would reduce the cross-section, and therefore reduce the pressure of the incoming air, which should ultimately lead to incorrect airspeed readings. Icing of the inlet openings and their blockage with ice leads to a violation of the indications of speed indicators , as well as altimeters, after which the crew receiving incorrect data could reduce the speed below critical, after which stall will occur and the aircraft will go into a dive. Given the low cloud cover, he will be able to see the earth at a very low altitude, when time to correct the situation may no longer be enough ^[13] .

There is also the possibility that due to the long-term presence in the icing zone, a thick layer of ice could form on the control surfaces, especially if the crew did not use the anti-icing system in a timely manner. At the same time, the aircraft got out of control of the crew after passing the beacon at an altitude of 3,500 feet. Although ice was already beginning to melt at altitudes below 5,000 feet, the accumulated layer could still be thick enough to affect flight performance so significantly. Moreover, the effect of wing icing on the flight characteristics of the aircraft at that time has not yet been studied properly ^[14] .

It is worth noting that the study of the debris did not reveal any signs of failures or malfunctions of the systems on board, so the main version was about the icing of the aircraft caused by the crew underestimating this danger and not taking timely measures, which ultimately led to loss of control and stall. But still, there is a possibility that one of the systems could fail or malfunction on board, however, severe destruction and the fire that occurred at the crash site destroyed these evidence ^[14] .

The cause of the accident, the commission of inquiry from the Civil Aviation Council called the loss of control of the aircraft during a decline to the Newark radio beacon. Investigators could not unambiguously determine the cause of the loss of control ^[15] .

• Accident ATR 72 under the Bellon

Comments

Sources

• Transocean Air Lines, Alvarado, California, March 20, 1953 (inaccessible link) . Civil Aviation Council (October 9, 1953). Date of treatment January 4, 2016. Archived January 29, 2016.