Vickers Viscount Crash in Charles City

Vickers-Armstrongs Viscount Model 745D (Vickers 745D Viscount) with registration number N7462 (factory number 217) was built on February 2, 1957 in the UK, and sold on March 2 to the American airline Capital Airlines. Its total operating time since the manufacture was 9247 hours. It was equipped with four Rolls-Royce Dart Model 510 turboprop engines equipped with Rotol model R130 / 4-20-4 / 12E propellers (blades of model RA 25842) ^[1] .

The flight crew (in the cockpit) consisted of two pilots ^[1] :

• The aircraft commander is 50-year-old James B. Fornasero. He has been with Capital Airlines since April 1, 1941, and on February 14, 1946 he was promoted to ship commander. He had a valid pilot certificate for Douglas DC-3 , DC-4 , Lockheed Constellation and Vickers Viscount aircraft . His total flight time was 20,850 hours, including 3,560 on Viscount.
• The second pilot is 36-year-old Philip H. Cullom, Jr. ( English Philip H. Cullom, Jr. ). He has been with Capital Airlines since July 14, 1953 and had a valid Douglas DC-3 pilot certificate. His total flight time was 5215 hours, including 2952 on Viscount.

Two stewardesses worked in the cabin ^[1] :

• 26-year-old Diane M. O'Donnell ( born Diane M. O'Donnell ). At Capital Airlines since March 6, 1959.
• 23-year-old Brigitte F.H. Yordt ( born Brigitte FH Jordt ). At Capital Airlines since March 25, 1959.

That day, the N7462 and its crew were scheduled to fly CA-020 from Washington to Norfolk . Flight 20 itself began in Chicago, but in Washington there was a change of aircraft and crew. The crew underwent pre-flight briefing, including information about the weather forecast, and began to prepare for the flight. In total, there were 44 adult passengers and two children on board, weighing about 7,260 pounds (3,293 kg), 1,047 pounds (475 kg) of cargo, 401 pounds (182 kg) of water-methanol and 12,000 pounds (5443 kg) of fuel. The main working weight of the aircraft (empty aircraft + crew) was estimated at 40,155 pounds (18,214 kg), that is, the total take-off weight of flight 20 was 60,863 pounds (27,607 kg). Then this weight was adjusted, taking into account the additional flight attendant and office mail, and as a result amounted to 61 083 pounds (27 707 kg). The maximum allowable weight for take-off from the 18/36 strip of Washington Airport was defined as 64,500 pounds (29,257 kg), and the maximum landing weight in Norfolk was 60,945 pounds (27,644 kg), that is, in the case of the N7462, its weight was within the established limits ^{[2] [3]} .

At 21:30 ^{[* 1]} flight 20 departed from the platform and headed towards the beginning of lane 36, and at 21:35 the crew received permission from the dispatcher: Capital 20, it is allowed [to follow] to Norfolk Airport via Springfield , by “Victor 3” to the Brooke radio beacon , further according to plan, maintaining a height of 5,000 feet (1,500 m ). Springfield passing at [height] 3,000 feet (910 m ); save 3,000 to two minutes after springfield; Passing Brooke at 5000 . At 21:40 take-off was performed, after which the crew immediately switched to the frequency of the exit dispatcher ^[3] .

Flight 20 first followed under the control of the departure airport radar, and after Springfield it came under control from the Washington Air Traffic Control Center and received permission from the latter to rise and occupy 8,000 feet (2,400 m ). Then the crew received new permission to follow the Victor 3 air corridor to Brook, after the Victor 286 to Tappahennock , after “Victor 213” to Hopwell , and from it directly to Norfolk, while maintaining a height of 8000 feet (2400 m ). Soon from the plane, they reported on Brook's passage at 21:53 and the estimated time to reach Tappahannock at 22:02. The dispatcher said that the radar control was terminated, and the crew must maintain contact with Washington until the passage of the Tappahannock, and then switch to communication with the center in Norfolk ^[3] .

At 22:01, the low-frequency crew reported to Norfolk about the passage of the Tappahannock and that they hoped to reach Hopwell at 22:12. Four minutes later, at 22:05, the dispatcher in Norfolk gave a new permit: Capital 20, is allowed to drive Norfolk from Tappahennock along Victor 213 corridor to Hopwell, 140 ° from Hopwell to Deep Creek, and directly to Norfolk's near drive . Keep 8000, communication with Norfolk — radar at [frequency] 118.5 after Hopwell . The crew confirmed receipt of information; it was the last radio communication with the board N7462 ^[3] .

According to eyewitnesses, the four-engine aircraft at low altitude made two large circles to the left, decreasing all the time, while it seemed to have problems with the engines, as the sound of a sharp increase in power was heard three times, and then as if the engines were turned off. The last noise of the increase in engine mode was heard at about 10:19 p.m., and immediately after that, an airliner with an 183 ° course crashed into a forest in the territory of Charles City County . The plane crashed with a pitch of 8 ° and almost without translational speed, almost flat, while strung on trees. The crash site was located at 8.4 nautical miles (15.6 km) in the azimuth of 067 ° from the Hopwell beacon and 6.3 nautical miles (11.7 km) east of the center line of the Victor 213 corridor. The resulting fire swept and destroyed the liner ^{[3] [4]} . All 46 passengers and 4 crew members on board died, which at that time made this disaster the largest with the participation of Vickers Viscount. This is also the largest disaster in the history of Capital Airlines (before its absorption, see below) ^[5] .

Exploring Debris

The airliner fell flat on the forest and almost without translational speed, as it was strung on five trees: two on each wing and one more passed through the tail cone. Collision with the ground occurred in flight configuration with flaps and landing gear retracted, all control systems on board before the collision with the ground worked normally, there were no signs of fire on board during the flight, fuel ring valves were turned off, the anti-icing system was not used ^[4] . Toggle switches of the anti-icing system were also in the off position ^[6] .

When examining the wreckage, it was noted that on both left power plants the propellers were plowed and their blades were installed at an angle of 84.4 °, while on both right power plants the propellers were in working position with a blade angle of 24–26 °. Moreover, on the propeller No. 3 (right inner), the blades were less damaged than on screw No. 4 (right outer). Thus, at the time of the accident, only engine No. 4 was operating at full power, while No. 3 had not yet reached the regime, and both left engines ( No. 1 and 2) were not working. The anti-icing system of all four engines was disabled ^{[4] [7]} .

Weather conditions

According to 19:00, eastern Michigan and Lake Erie were dominated by a cyclone , and its center advanced southeast, with lowering pressure to southeastern Virginia . The cold front began north of Raleigh ( North Carolina ) and reached Tampa ( Florida ), while the warm front followed north along the coast near the borders of Virginia and North Carolina. Three hours later, at 22:00, a cold front extended already between Blackstone and Norfolk (Virginia), and the cyclone's eye was about a hundred miles (one and a half hundred kilometers) east of Delaware Bay. Based on these data, the National Meteorological Service compiled a weather forecast for Virginia, East Maryland, Delaware and northeast North Carolina, according to which cloudy weather with gleams and a lower boundary of 100 feet (30 m ) to 400 feet (120 m ), light rain was expected , fog, visibility from ½ to 2 miles. Some improvement in weather after midnight was also expected, but there could be thunderstorms in the coastal waters area before midnight. The icing zone in eastern West Virginia was between 4,000 feet (1,200 m ) and 5,000 feet (1,500 m ), and to the east of North Carolina, it was already between 8,000 feet (2,400 m ) and 9,000 feet (2,700 m ), and then decreased already to the surface in the east of West Virginia. west of Maryland and the highlands of Virginia ^[7] .

According to the weather service in Norfolk at 9:30 p.m., the sky was partly cloudy with a height of 700 feet (210 m ) and continuous cloudy at 6,000 feet (1800 m ), visibility in the fog was 4 miles (6.4 km ). An hour later, according to 22:31, visibility in the fog improved to 6 miles (9.7 km ). According to eyewitnesses, in the area of ​​the incident, it rained heavily in the region for an hour or two before the disaster, sometimes with hail, accompanied by a strong wind, and sometimes thunder was heard. Crews of other aircraft reported mild to moderate turbulence, heavy rain and fog. In the area of ​​coastal waters, turbulence was already strong, and severe icing was also observed. All these weather phenomena corresponded to the weather forecast that the crew received before departing from Washington ^[8] .

Tests

The flight took place in cloudy conditions, but the crew did not include an anti-icing system. Thus, it turned out that ice deposition on the plane could occur. The problem is that the Vickers Viscount is equipped with Rolls-Royce Dart turboprop engines, which, if foreign objects, including ice, get caught in a flame , which means the engine stops. According to the manufacturer, to break the flame, according to the tests, it is necessary to get ice pieces weighing 3.5-4 pounds (1.5-2 kg) inside, which is equivalent to a layer of ice with a thickness of ¼ — ½ inch (1-11 cm), formed on the inside of the input guide vane . In general, until July 1958, the minimum temperature for switching on the anti-icing system on Viscount aircraft was set to +5 ° C, but after this date (due to the disaster in Freeland ) it was increased to +10 ° C. Changes were also made to the guidelines for the use of the de-icing system, but as it was established, Capital Airlines did not make these changes to the rules for pilots, continuing to use the rules of 1957 ^{[8] [8] [6]} .

The current rules provided that in the event of a flame failure under icing conditions, it was first necessary to plumb the propeller, then restart the engine, or first lower to a layer of air with a temperature of at least 0 ° C to clear the engine of ice, naturally, with the anti-icing system ^{turned on [9]} . Then the investigators decided to check how much battery power is enough. if all four engines stop working and their de-icing system is turned on. As tests showed, in this case the discharge current reached 500 amperes, and after a minute and a half, the charge was not enough for a normal restart of the motor. In this case, the engines can still be started by putting them in autorotation mode, manually removing them from the feathering mode. According to tests, for such a situation, at least 150 knots were needed to start engine No. 4 , and at least 180 knots to start engine No. 3 ^[10] .

Data Analysis

Based on the results of the investigation, we can add the following picture of events.

After the departure from Washington, the Vickers flew into the clouds and then, following them, until the occupation of a given echelon, followed. Given the testimony of other crews that the tops of the clouds reached 10,000 feet (3,000 m ), or even 13,000 feet (4,000 m ), it turned out that at a cruising altitude of 8,000 feet (2400 m ) he also fell into them, and taking into account the general the flight time was in them a total of about 10-15 minutes. The cloud itself was layered, with the border of the upper layer at an altitude of 6000 feet (1800 m ), while the lower layer was from 3000 feet (910 m ) to 4000 feet (1200 m ). At that time, the region was dominated by a small but powerful cyclone, which however was aloof, so that the flight as a whole took place in calm weather ^[10] .

However, there was icing in the clouds, which began in the Washington area from 5,000 feet (1,500 m ), and at 8,000 feet, the air temperature was −8 ° C. In the area of ​​the incident, icing was observed at 6000 feet (1800 m ), and the air temperature at 8000 feet was −4 ° C ^[10] . To leave the icing zone, the crew would have to drop below 6,000 feet, but then at an altitude of about 4,000 feet (1,200 m ), it would fly into another layer of cloud, the lower boundary of which was no higher than 400 feet (120 m ). Actual weather conditions in this case led to the formation of an ice layer on the glider ^[11] .

It can be argued that all engines stopped on board, and the crew did not turn on the anti-icing system, or turned it on, but late. The fuel heating was turned off, so there was a version that ice crystals formed in the fuel due to water entering the tanks, after which this ice clogged the filters, blocking the fuel flow to the engines. But checking the fuel showed that it was clean, without signs of water, and therefore ice could not form in it. But on the other hand, ice could have formed on the input guide vanes, after which if the crew had made a belated decision to turn on the heating of the power plants, then the melted ice could come off the hull and fly into the engines, where it could lead to a flame failure. Test flights have confirmed that such a scenario is quite possible ^[11] .

The last radio communication with the crew was completed at 22:05 14 minutes before the accident and 40 miles from the crash site, while the crew did not report any problems. There were no more messages on board N7462, which means that when an emergency occurred, it required the crew to concentrate fully, which is why he did not even report anything to the ground. It is possible that the crew did not know that the anti-icing system had to be turned on throughout the flight under icing conditions, and therefore it turned on with a delay when an ice layer had already formed. This layer of ice from the airframe got into the engines, as a result of which all four engines stopped at once. As a check of the history of all “Viscounts” showed, there were already 18 cases, and all on different planes, when during the flight there was a drop in traction on all four engines, but those cases, fortunately, cost no casualties ^[12] .

If one engine failed, the plane could continue flying at the echelon, but in this case all engines failed, so the crew used the 1957 manual and began to fall below the icing zone. The reduction was probably carried out at a standard speed of 237 knots, after which the crew tried to start the engines after falling into the warm air zone, being careful not to lose altitude. But since the flame outage was caused by ice ingress, and the latter continued to remain inside, the system continued to automatically feather the propellers, so the crew tried to manually set the screws to autorotation mode, as well as to get rid of the ice in at least one of the engines using an electric heating. These actions took about three minutes, if not more, and therefore the batteries managed to discharge below the level necessary for the successful starting of the engines. In addition, the flight speed continued to decline and was soon already insufficient to maintain altitude, and therefore the aircraft began to decline again ^{[12] [13]} .

Then the crew could try to start the engines using autorotation, for which he directed the car to decrease. In this case, for starting external engines ( No. 1 and 4), a speed of at least 150 knots was required, and for starting internal engines ( No. 2 and 3) - at least 180 knots. Based on the results of the survey of the wreckage, it can be argued that the crew managed to start the engine number 4 . At the same time, due to previous unsuccessful attempts, an excess of fuel could accumulate in it, which then ignited when the engine was started, creating an explosive noise that was heard by eyewitnesses. Flight tests testified that if only one of the extreme engines will operate at full power, while the rest will be feathered, a turning moment will arise, in this case to the left, accompanied by a loss of altitude. Witnesses heard short-term noise of increasing power, that is, the crew tried to start the engines. The next engine, which was able to start, turned out to be No. 3 , that is, now both right engines were working ^{[13] [14]} .

The aircraft was designed for safe flight, when the engines work only on one side of the wing, but the crew could reduce their power for safety in order to reduce the turning moment. At the same time, the commander did not take into account that in the process of starting the engines there was a loss of altitude, which was difficult to notice during a night flight in the clouds. When the crew unexpectedly saw land in front of them, acting at the level of the self-preservation instinct, they could sharply pull the helms “towards themselves”, forcing the plane to sharply raise its nose. Due to such an action, however, the machine quickly lost its translational speed, switching to stall mode, and then crashed down directly onto the forest ^[14] .

Cause of the disaster

September 15, 1961 was published, and on September 21, a report was published according to which the cause of the disaster was the late activation of the anti-icing system, resulting in a loss of traction in all engines, and then the electricity needed to operate the propellers normally and restart the engines to continue normal flight ^[15] .

First of all, it is worth noting that in the past two years this was the fourth (and largest) disaster involving Vickers Viscount of Capital Airlines, which led to a significant undermining of confidence in the latter. In addition, Capital was criticized that, being one of the main operators of Vickers Viscount aircraft, it nevertheless did not promptly inform its crews about all changes in the manual for the flight operation of the aircraft. As early as May 1960, the airline excluded all Viscontons from its fleet, and the danger of bankruptcy was already evident. Then she agreed to merge with her main rival, United Airlines , which was completed on June 1, 1961, after which the latter became the largest airline in the country.

The crash of flight 20 showed all the danger of icing for gas turbine engines that all engines could fail simultaneously, thereby creating an emergency situation that the crew could not cope with. As a result, additional research was started on the protection of engines from this factor. The certification of anti-icing systems was changed, and modern engines, including those on the Boeing 777 , began to rely on the simultaneous ingress of all ice accumulated on the inlet guide van. Also changed the system of automatic feathering propellers ^[16] .

Vickers Viscount itself was the first-born of turboprop aircraft, which in those years had just begun to take up its positions in civil aviation, but they were overshadowed by a series of incidents. After all, gas turbine engines ( turboprops and turbojets ) were radically different from piston engines, which in turn were used on Wright brothers' aircraft and, as a result of improvement over the next half century, became quite reliable and relatively unpretentious to many factors. Gas turbine engines were completely different. Their open gas-air path was vulnerable to the ingress of foreign objects, such as ice, and therefore the protection that was used on piston engines was not enough in this case. Another factor was that turbofan engines developed higher rotational speeds, and a screw rotating at such speeds, which is in autorotation mode, creates a much greater aerodynamic drag compared to piston engine screws. It also required additional research, this time to study aircraft controllability in a given situation ^[17] .

• Accident An-24 over the Sivash Bay

Comments

Sources

• CAPITAL AIRLINES, INC., VICKERS-ARMSTRONGS, VISCOUNT, N 7462, NEAR CHARLES CITY, VIRGINIA, JANUARY 18, 1960 (English) (unavailable link) . Civil Aviation Council (September 20, 1961). Date of treatment June 21, 2015. Archived on May 28, 2015.

• Looking Back: Muskegon pilot, 49 passengers and crew perish in 1960 airliner crash . MLive.com (January 18, 2010). Date of treatment June 21, 2015.
• Holdcroft, VA Airliner Crash Kills Fifty, Jan 1960 . GenDisasters. Date of treatment June 21, 2015.