DC-8 crash near New Orleans

The flight crew (in the cockpit) consisted of three people ^[1] :

• The aircraft commander is 47-year-old William B. Zeng. He was qualified as a pilot of Douglas DC-3 , DC-4 , DC-6 , DC-7 , DC-8 , Martin 202/404 , Lockheed Constellation and Lockheed L-188 Electra aircraft , as well as single-engine aircraft. The classification of the type DC-8 received January 8, 1962. He had a total flight experience of 19,160 hours, including 916 hours on DC-8.
• The co - pilot is the 39-year-old Grant R. Newby. He had pilot qualifications for Martin 202 and 404 , as well as single-engine aircraft. He had a total flying experience of 10 734 hours, including 2404 hours on DC-8. It is worth noting from his past the incident that happened on November 9, 1963 in the sky over Houston ( Texas ), when another DC-8, the N8603, on which Newby was a co-pilot, at an altitude of about 19,000 feet (5800 m ) under control and went into decline, before the crew managed to regain control and level out at an altitude of 5000 feet (1500 m ). After 12 days, on November 21, Grant Newby was again allowed to work as a pilot and has since completed another 20 flights with a total duration of 214 hours.
• The third pilot / flight engineer is the 39-year-old Harry Idol. He was qualified as a pilot of Martin 202 and 404 aircraft, single-engine aircraft, as well as a flight engineer of multi-engine aircraft. In addition, he had a pilot-instructor certificate. His total flight experience was 8300 hours, including 1069 hours as a DC-8 pilot / flight engineer.

All three arrived in Mexico City at 22:05 on February 23, that is, a day before the adoption of flight 304.

In the cabin on a fateful flight, four stewardesses worked in New Orleans ^[1] :

• The 36-year-old Grover W. Flowers has been with the airline since October 9, 1950.
• 21-year-old Barbara D. Norman ( born Barbara D.Norman ) - in the airline since November 30, 1962.
• 24-year-old Tove E. Jensen has been with the airline since April 5, 1963.
• 21-year-old Mary Ann Thomas has been with the airline since July 26, 1963.

Douglas DC-8-21 with registration number N8607 (factory - 45428, serial - 61) was released in February 1960 . May 22, the airliner arrived at the customer - American airline Eastern Air Lines; his operating time at that time was 12.3 hours. The airline also assigned a fleet number 607. The aircraft was equipped with four Pratt & Whitney JT4A-9 turbojet engines, each of which developed a thrust of 16,800 pounds (7,600 kg). The total operating time of the side N8607 was 11,340 hours ^{[1] [3]} .

Late on Monday , February 24, 1964, the N8607 board at 22:12 ^{[* 1]} arrived in Mexico City ( Mexico ). The handing over crew on the plane had only one remark: the inoperative flap compensator. This required an increase in effort for deviations of the helm “toward you” or “from yourself” (for raising and lowering the nose, respectively), but nonetheless allowed you to fly. Then the plane began to prepare for the return flight - EA-304, along the route Mexico City - New Orleans - Atlanta - Washington - New York . In New York, it was planned to carry out aircraft repairs. To facilitate control, the crew submitted a flight plan to follow at a reduced air speed. Then flight 304 flew out of Mexico City and at 00:51 on February 25th safely landed in New Orleans. Piloting at this stage, according to available evidence, was performed by the commander. Subsequently, the boarding passengers described the flight as normal, only half an hour before landing, the airliner fell into the turbulence zone, from mild to moderate ^{[4] [5]} .

In New Orleans, several passengers got off the plane and boarded new ones, as well as a change of stewardesses. In total, there were 51 people in the cabin. The total weight of the airliner was estimated at 213,871 pounds (97,010 kg) with a maximum allowable 215,000 pounds (98,000 kg). Calculation centering was 25.2% of the SAH, with established limits from 16.5 to 32% of the SAH. A total of 51 passengers and 7 crew members were on board when the take-off and landing controller gave permission to take off, after which at 01:59:46 the airliner started to take off on the runway and then took off ^[5] .

At 02:01, the take-off manager instructed flight 304 to switch to communication with the control dispatcher, which was confirmed. As the take-off manager later said, he saw a plane flying in the dark about two to three miles north of the airport, after which the lights disappeared into the clouds. Also, flight 304 was also seen by the crew of another jet flying out of New Orleans at 02:02, according to the testimony of which the board of N8607 disappeared in the clouds after passing a height of 1200 feet (370 m ). At the same time, the crew was instructed by the control controller to turn right to course 030 ° in order to enter the air corridor J37, according to which the flight was scheduled. The dispatcher then contacted the New Orleans District Air Traffic Control Center, where he was told that they were observing the aircraft’s mark five miles north of the New Orleans radio beacon, after which at 02:02:38 the radar control of flight 304 was transferred to the district center. The crew was instructed "... communication with the radar center New Orleans, frequency 123.6" , to which from the plane at 02:03:15 reported "Okay" . This was the last known radio communication with the N8607 board. Flight 304 at that time was 8 miles from the airport and followed course 030 °. According to weather stations, as well as crews of other aircraft, thunderstorms with heavy rains, northern and northeast gusty winds, and moderate to strong turbulence were observed in the region at that time ^{[5] [6] [7]} .

A couple of minutes passed, and flight 304 still did not get in touch. Then at 01:05:40 from the control center they called the dispatcher to make sure that the crew received the necessary instructions. During these negotiations, both dispatchers suddenly noticed that the flare of Flight 304 disappeared from the radar screens, so an alarm was given that began the search for the missing aircraft. Around the same time, residents of Lake Ponchartrain heard a strong rumble and roar, after which a fire appeared on the surface of the water. At a distance of 14.5 miles in azimuth 34 ° from the radio beacon of the Douglas airport, it crashed into the surface of the lake and exploded, and all 58 people on board died ^[5] .

After reporting what had happened, a large oil stain was discovered by helicopter on the surface of the lake. As a result of searches at the crash site, most of the wreckage of the aircraft was discovered, including the flight recorder . A study of the records from the “black box” showed that information about the last 150 hours of flight was preserved, but at the same time the recording was cut off at the landing in New Orleans, and the data of the fateful flight were not recorded. That is, the commission did not have objective data on the flight ^[8] .

Investigation of the causes of the incident significantly complicated the lack of information that was caused by three reasons ^[9] :

1. Air traffic at the airport was rare, and therefore the dispatchers did not constantly monitor the planes by radar and did not require frequent reports from crews on their location, altitude and speed of flight.
2. The plane crashed into Lake Ponchartrain, which in itself complicated search work, including many fragments that were not found.
3. Fatal flight data were not recorded on the magnetic tape of the flight recorder.

Aircraft Technical Condition

When studying the history of the N8607 board from the moment it arrived at the airline, it was discovered that on August 20, 1963, it fell into a zone of strong turbulence. A check at the same time showed that also the design of the aircraft was damaged, but very small. However, on September 11, 1963, when landing in San Juan ( Puerto Rico ), the stabilizer was stuck in a position of maximum deviation for diving, but then the situation was saved. After that, the worm gear reducer of the stabilizer drive was repaired, including the replacement of the gear and the removal of metal particles. At the same time, the gearbox was not disassembled, since, according to the aircraft that it was repairing, it was normal practice for the airline to repair this unit without disassembling it. After that, no more records of repair of the stabilizer drive were found ^{[10] [11]} .

It was also found from aircraft logbook entries that on-board computer N8607 has lately recorded eight cases with flap compensator failure, including four times in the last week. February 18, that is, a week before the incident, technicians discovered this failure in computer records, but did not begin to eliminate it. This was largely due to the fact that the on-board computer with serial number 268D installed on the aircraft was released in 1960 and then over the next four years was removed from various aircraft fifteen times, of which six times occurred due to false signals about rudder failure heights. The tests used in the EAL did not allow us to detect the cause of such violations in the operation of the computer ^[11] .

Among other things, over the past 30 days, there have been eleven incidents of autopilot malfunctions on the plane, of which two times there were irregularities in the yaw channel control, six in the longitudinal control channel, and in three cases the autopilot turned off altogether. February 18, 1964 on the plane there was a failure at once of both main horizons , which was corrected by replacing the unit with the instrument switches, from which the main horizons were powered ^[11] .

Data Analysis

Flight 304 performed a normal take-off from the runway and began a seemingly normal climb. The weight and alignment of the liner were within the established limits, and the crew was quite qualified. and before that I normally rested in Mexico City. All reports from airplane to land have never reported any problems on board. At 02:02:38 a.m. flight 304 was five miles from the beacon, when it was instructed to switch to communication with the dispatcher in the radar center. At 02:03:15, they confirmed receipt of information from the plane, but they did not contact us anymore. The last time the flight mark 304 was observed on the radar 6.5 miles northeast of the beacon and headed at 030 ° ^[12] .

To determine the probable flight path of flight 304, tests were conducted with another DC-8, which was loaded so that the weight and alignment were similar to flight 304. Since the disappearance of the aircraft was noticed at 02:05:40, this time was taken as the latest likely disaster time. Given the reports from the crew, the disaster occurred no later than at 02:05. Thus, the time of the disaster was defined as 02: 05: 00-02: 05: 40, that is, in the interval of about 40 seconds. If we take the lifting speed as the maximum allowable - 310 knots, and the disaster time - 02:05:40, then according to the test data, the maximum flight height in this case would be 7000 feet (2100 m ). Although it is worth noting that, taking into account turbulence and other weather factors, the ascent rate was still lower. After examining the test results, the commission came to the conclusion that the climb was carried out with an air speed of at least 250 knots. The zone of probable icing was at an altitude of 9000 feet (2700 m ), that is, above the possible flight path of the side of the N8607 ^{[13] [12]} .

Climbing up to 1000 feet (300 m ), the liner flew into the clouds, the peaks of which were at an altitude of 5000-6000 feet (1500-1800 m). These clouds were located in a very elongated cyclone, stretching from northwest to southeast. Records of flight data from the “black box” of another aircraft that flew out of New Orleans following Flight 304 were checked at intervals of several minutes. According to these data, the aircraft fell into the turbulence zone, with overloads ranging from 0.2 to 1.9 units at altitudes from 2000 feet (610 m ) to 6000 feet (1800 m ), that is, the turbulence was quite strong. However, the crew could not give serious attention to this turbulence by starting to climb at a speed of at least 310 knots ^[13] .

The debris in the lake was found very close to each other, that is, until the moment of impact on the water, the structure was not destroyed in flight. It is also possible that the engines at this moment were operating in reverse mode, that is, to create reverse thrust. This version arose due to the fact that such an action was already taken by the Newby co-pilot in the incident of November 9, 1963, when the board of the N8603 lost control for a while and switched to a rapid decline. According to the testimony of the second pilot, made after that incident, the use of reverse thrust not only increased the braking effect, but also forced the nose of the aircraft to rise. As for the control planes, taking into account the past aircraft, it is most likely that at that time there was also a failure of the stabilizer drive, which deprived the crew of the ability to effectively control the aircraft in the longitudinal direction ^{[12] [14]} . Since the test flights were carried out under relatively good weather conditions, which differed from the real ones that the N8607 board fell into, it was not possible to accurately reproduce the situation ^[15] .

More thorough tests were carried out to study the interaction in the "man - medium - machine" system and it was determined that turbulence is sometimes so strong that oscillations with a frequency of 0.2 to 4 Hz occur in the aircraft itself. One of the pilots who flew on the N8607 described that somehow, when approaching Dallas on this aircraft, he encountered strong turbulence, and strong blows occurred. According to the pilot, for his 20 thousand flight hours, these were the most powerful blows during turbulence. In this case, sounds arose as if the liner was breaking up, and the readings of the instruments became blurry and it was impossible to read. Loose objects flew up to the ceiling, and the pilots even thought that they had rolled over. This all lasted from 20 to 100 seconds before the crew managed to stabilize the car at an altitude of 1400-1500 feet at an air speed of 250 knots ^[16] .

In general, during the investigation, insufficient stability of the DC-8 aircraft was noted, especially when the flap compensator failed at a speed of 310 knots. It is possible that at some point the plane raised its nose above what was necessary, to which the crew turned the helms "away", but taking into account its own hesitation, the liner reacted too sharply and quickly lowered its nose at a sharp angle. From the analysis of the radio communications, it was possible to identify the voice of the commander who was communicating with the ground, that is, the second pilot was controlling the aircraft at that moment. When the car got out of control and lowered its nose, the second pilot, remembering the case of three months ago, began to take the same actions, including putting the engines in reverse thrust mode. However, in this case, he only aggravated the situation, because for a successful exit from the peak, 13,000 feet (4000 m ) of height were required, which the crew did not have ^{[17] [18]} .

The commission came to the conclusion that the flap drive failed due to an inoperative compensator on the plane. It is impossible to determine the exact time of failure; it could have been during preparation for takeoff, but the probability of failure was too high. Because of this, the flaps were released at a certain angle, which worsened the aircraft's handling characteristics. Then, while climbing, the airliner flew into the clouds, where it fell under the influence of turbulence. By themselves, each of these factors is relatively harmless, but together they led to the fact that the Douglas, having lost stability in the longitudinal direction, lowered its nose. Piloting at this moment was carried out by the second pilot, who, in the conditions of flying at night in the clouds, was disoriented and began to take the wrong actions, as a result of which the plane went out of control ^{[19] [20]} .

Similar incidents ^[21]

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Comments

Sources

• EASTERN AIR LINES, INC, DOUGLAS DC-8, N8607, NEW ORLEANS, LOUISIANA, FEBRUARY 25, 1964 (inaccessible link) . Civil Aviation Council (1 July 1966). Date of treatment April 21, 2015. Archived January 29, 2016.

• Adriane Quinlan. 50 Years after Eastern Air Lines Flight 304 crashed into Lake Pontchartrain leaving no survivors, something still remains . New Orleans, LA Local News (February 25, 2014). Date of treatment April 28, 2015.
• ASN Aircraft accident Douglas DC-8-21 N8607 New Orleans International Airport, LA (MSY ) . Aviation Safety Network . Date of treatment April 28, 2015.