The crash of Boeing 707 in Pago Pago

Boeing 707-321B with the serial number 19376 and serial 661 made its first flight on December 15, 1967 ^[5] . The aircraft received the tail number N454PA, and by December 20 it was sold to the customer - the American airline Pan American World Airways , where it also received the name Clipper Radiant . The four turbofan engines installed under the wing were Pratt & Whitney JT3D-3B models with a thrust force of 18,000 pounds (8,200 kg) each ^[6] . The passenger capacity of the cabin was 192 seats. The flight certificate for the aircraft was obtained on January 11, 1968 ^[7] .

Operation and maintenance of the aircraft was carried out, according to the report of the airline, in accordance with the directives in force at that time. The last major inspection of the N454PA was conducted on April 22, 1973 in Miami , Florida . The last maintenance in form “B” was carried out on January 24, 1974, and in form “A” - on January 30 of the same year at Auckland Airport before departure. Before the flight, the aircraft had a total operating time of 21,625 flight hours. According to calculations at the time of the crash, the weight of the airliner was 245.4 thousand pounds (including 68.5 thousand pounds of fuel) with the centering 26.2 of the MAR, which was within acceptable limits ^[8] .

The flight crew consisted of four people:

• The commander of the aircraft - Leroy A. Petersen ( eng. Leroy A. Petersen ). 52 years old, in the airline since March 3, 1951. He also had the qualification of a radio operator and a flight engineer . On November 1, 1960, he was qualified for backup co-pilot and flight engineer B707 , on July 2, 1965 he was upgraded to full co-pilot B707, and on November 10, 1967 - to commander B707. He was qualified to fly the Douglas DC-4 , Boeing 337 , 707 and 720 . Had a total plaque of 17 414 hours, including 7414 hours on the B707 ^[9] .
• The co - pilot is Richard V. Gaines ( born Richard V. Gaines ). 37 years old, in the airline since August 7, 1964. He also had the qualification of a radio operator and a flight engineer. October 20, 1964 was qualified for backup co-pilot and flight engineer B707 , June 15, 1967 was upgraded to full-time co-pilot B707. He was also qualified to fly the B720 . Had a total raid of 5107 hours, all on B707. The flight over the last 60 days was 127 hours and 14 minutes, and over the last 30 days, 56 hours and 44 minutes. In the Pago Pago over the past 12 months, flew 12 times ^[9] .
• Third pilot - James S. Phillips ( eng. James S. Phillips ). 43 years old, in the airline since April 25, 1966. He also had the qualification of a radio operator and a flight engineer. On January 3, 1967, he was qualified for backup co-pilot and flight engineer B707 . Had a total raid of 5208 hours, including 4706 hours on the B707. The flying time in the last 60 days was 119 hours, 7 minutes, and in the last 30 days, 56 hours, 7 minutes. In Pago Pago for the past 7 months, flew 7 times ^[10] .
• Flight engineer - Jerry W. Green ( eng. Gerry W. Green ). 37 years old, in the airline since April 24, 1967. On October 20, 1967, he was qualified for backup co-pilot and flight engineer B707 , and on July 2, 1973 he received the initial qualification of flight engineer B707. Had a total raid of 2399 hours, including 1,444 hours on the B707. The flight over the last 60 days was 82 hours and 15 minutes, and for the last 30 days, 63 hours and 13 minutes. In Pago Pago for the past 7 months, flew 7 times ^[10] .

All four flight crew members for the last 24 hours had a general time distribution: 19 hours 14 minutes of rest in Auckland before departure and 3 hours 46 minutes of flight time. Six flight attendants worked in the cabin ^[11] :

• Elizabeth Givens ( born Elizabeth Givens ) - was born on September 28, 1943 , in the airline since July 1, 1966 ;
• Gorda Rapp ( born Gorda Rupp ) - was born on September 12, 1939 , in the airline since March 18, 1966 ;
• Gloria Olson ( born Gloria Olson ) - was born on June 4, 1948 , in the airline since February 14, 1972 ;
• Patricia Riley ( born Patricia Reilly ) - born July 22, 1948 , on the airline c May 8, 1972 ;
• Kinuko Seko ( born Kinuko Seko ) - was born on March 19, 1945 , in the airline since May 1, 1969 ;
• Yvonne Cott ( born Yvonne Cotte ) - was born on April 10, 1950 , in the airline since February 19, 1973 .

The aircraft served a regular passenger flight PA-806 (call sign - Clipper 806 ) from Auckland ( New Zealand ) to Los Angeles ( California , USA ) with intermediate stops in Pago Pago ( American Samoa ) and Honolulu ( Hawaii , USA) ^[12] . Estimated fuel consumption at the first stage of the flight (before Pago Pago) was to be 48,500 pounds (22,000 kg). At the same time, 117,000 pounds (53,100 kg) of jet fuel A-1 were poured into the tanks, of which 37,900 pounds (17,190 kg) pounds should have been left for the final stage of the voyage ^[8] . At 20:14 ^{[* 1]} with 91 passengers and 10 crew members on board flight 806 departed from Auckland to Pago Pago, performing flight on the IFR ^[12] . During the takeoff, piloting was carried out by Commander Leroy Patersen. It is worth noting that co-pilot Richard Heins had laryngitis , so he was sitting in a folding seat at the end of the cockpit. The third pilot, James Phillips, performed the duties of a co-pilot on this flight and sat in the right-hand seat. Further in the text, the co-pilot defaults to it as the one ^[13] .

At 11:11:55 pm, the crew contacted Pago Pago Airport Controller and reported that they were 160 miles south of the airport. The dispatcher responded by transmitting: Clipper eight zero six, understood. Weather forecast in Pago: partly cloudy [high] one thousand six hundred [feet (490 m)] and variable four thousand [feet (1220 m)], the observed one thousand (300 m) is solid. Visibility one zero [10 miles (16 km )], temperature seven eight [ 78 ° F (26 ° C) ], wind three five zero degrees, one five [ 7.7 m / s ], altimeters two nine eight five [ 29.85 in. (758 mm) Hg. ] . At 23:13:04 the crew received permission from the approach controller to proceed to the Pago Pago VORTAC navigation radio beacon (Pago Pago VORTAC). Three minutes later, at 23:16:58 from the plane, they reported leaving train 330 (10 km). Soon the descending flight 806 crossed the echelon 200 (6.1 km), which was reported to the ground at 23:24:40. Then at 23:24:49 the dispatcher of approach approached: Clipper eight zero six, you are allowed to enter lane 5 by ILS DME ^{[* 2]} , after two zero miles turn to the south-south-west. Report on the turn and descend from five thousand (1.5 km) . When at 23:30:51 the aircraft was asked about the direction and speed of the wind, they were informed that the wind was on a course of 360 ° with deviations up to 020 °, a speed of 10-15 knots (5-7.7 m / s ). Then at 23:34:56 the crew reported that they were at an altitude of 5500 feet (1700 m ) above sea level and intercepted the vector 226 ° from the VOR beacon . In response, the approach controller instructed to receive three signals from the beacon and, when reporting on the location of the aircraft, only report them. Information on wind was also transmitted: 010 °, 15 knots, in gusts up to 20 knots [ 10 m / s ] ^[12] .

At 23:38:50, the dispatcher reported that there was a suspicion that a power failure had occurred at the airport, but the co-pilot reported that the signal from the VOR was still being heard, and the runway lights were on, including high intensity lights . At 23:39:05 the dispatcher asked the crew whether the strip lights were observed, to which the answer was positive. Then the dispatcher said that the weather was bad at the airport and it was raining heavily, so there were no lights from his post (there was no control tower at the airport ^[14] ). At 23:39:29 the co-pilot Phillips relayed: We are now 5 miles from DME and they still burn brightly . Then the approach controller said: Ok, there are no other reports on the situation on the trajectory. Wind zero three zero degrees, two zero, in gusts two five [ 10 m / s ]. Notify band release . In response, at 23:39:41 it was reported: Eight zero six, so sure . This was the last radio message from the aircraft ^[15] .

The commander asked the co-pilot if he saw the lane, to which an affirmative answer was given. The flaps were set to 50 °, the wipers worked, and the control card was fully read before landing. As the co-pilot later reported, the only thing that he did not perform before landing was that the navigation receiver No. 2 (right) was not switched from the VOR frequency to the course-glide path system at the final landing stage. At 23: 40: 22.5 the co-pilot suddenly said: We are a little high . Then, after four seconds, the pilots slightly deflected the steering wheels "from themselves," that is, they slightly lowered the nose of the aircraft. However, then twice, at 23: 40: 29.5 and 23:40:34, warning signals of a radio altimeter about dangerously low altitude above the ground were heard, while the second such signal was interrupted by the co-pilot, who shouted: We are at the minimum [height] . At 23:40:35, the co-pilot also said: I see the airfield ... [in a few seconds] Turn right ... One hundred forty knots . This was the last phrase recorded on a voice recorder. It is worth noting that in the last 59 seconds neither Flight Engineer Green, nor Pilot Gaines, who was sitting on the folding seat, made any comments on the implementation of the approach. The co-pilot himself, however, subsequently could not remember whether he had observed the lights of the visual approach indication system ( VASI ) ^[15] .

At 11:40:42 pm, an airliner flying in the darkness at a distance of 3,865 feet (1,178 m ) from the end of the runway and 113 feet (34 m ) above sea level (88 feet (27 m ) from the ground ^[16] ) crashed into the jungle . Having lost speed, the Boeing crashed to the ground after 236 feet (72 m ) and rushed through the trees until it crashed into a three-foot (about a meter) lava rock and then stopped 3090 feet (940 m ) from the end of the strip at There were no witnesses of the accident on the ground ^[15] . According to the testimony of the surviving passengers, when the airliner raced through the trees, and even when confronted with a small rock, the blows were only slightly stronger than during a normal landing, and the interior trim was almost not damaged. When the car stopped, a fire broke out on the right wing of the wing, but no evacuation of the cabin was announced. One of the passengers opened the right emergency exit overlooking the wing, and managed to jump out, after which the fire cut off this exit. A few more people opened the left emergency exit and got out through it. Most of the passengers ran to the beginning and the tail of the liner to the usual exits, but the flight attendants could not open those doors. Meanwhile, the fire flared up completely engulfed and destroyed the airliner ^[3] . Several people who were waiting for Flight 806 at the airport reported that they had seen a flash near the lane 5. As it turned out later, it was an airplane explosion ^[17] . Debris scattered over an area of ​​775 feet (236 m ) long and 150 feet (46 m ) wide ^[16] .

At 23:43 the first alarm signal arrived at the airport fire station . At that time, a small car with two firefighters was standing at the beginning of the runway - standard practice at this airport when an aircraft was expected to land. However, fire calculations were delayed with departure, because of the confusion it was not clear what actually burns - the house or the plane. In addition, as it turned out later, the crash site could only be reached via a local single-lane road ^{[18] [3]} . Only 14 minutes after the moment of the disaster, the fire and rescue services reached the burning plane ^[19] . They found only 10 survivors: 9 passengers and 1 crew member - third pilot James Phillips ^[20] (climbed through a breach in the cockpit ^[3] ), acting co-pilot. However, the next day after the incident, one passenger died from his injuries, February 2 (3 days after the disaster) - the pilot and three passengers, and February 8 (9 days after the disaster) - another passenger. In total, 97 people died in the crash. It is worth noting that at that time a person who died more than 7 days after the incident was related to mortally wounded (paragraph 830.2 of section 49 of the Code of Federal Regulations ), therefore, in the NTSB report, the death toll is indicated as 96 ^[13] . This is the largest plane crash in American Samoa ^[4] .

Analysis

The plane until the crash was fully operational and certified, and its weight and centering when departing from Auckland and landing at Pago Pago did not go beyond the permissible limits. The crew had the necessary qualifications and was prepared for the flight. Based on the results of the investigation, the testimony of the third pilot and the records of the flight recorders, the commission concluded that there were no system failures or destruction of the aircraft structure, including engines, airframe structures, control surfaces, electrical and hydraulic systems, and flight instruments, before the collision. Methyl ethyl ketone peroxide in the cargo compartment was packaged improperly, but no evidence was found that this was the cause of the disaster ^[21] .

According to data from the flight recorders, including speech, and from the words of the pilot who survived the crash, the following picture of landing performance was established. 8 nautical miles (14.8 km) remained until the end of the lane when the co-pilot reported that he saw the lane. From the moment the plane was 7.5 nautical miles from the end of the runway, the pilot reported to the ground five times about the observation of the runway lights. All systems of the airliner at that time were working properly. The minimum height of entry into the glide path is set at 2500 feet (760 m ), however, the car dropped to 2000 feet (610 m ), after which it remained at this height until the entrance to the glide path . When the entry to the glide path was reported, flight 806 was actually 180 feet (55 m ) below the altitude of 2180 feet (660 m ), the normal height of the glide slope at that point. Why the liner fell under the glide path, the commission could not establish. To some extent, this was due to the fact that even 7 miles from the DME, the right-hand radio receiver was still tuned to the VOR frequency, and not the heading-glide system. As practice shows, do not be such an error, the right pilot could more effectively control the implementation of the approach. In addition, the commander and the co-pilot could at the same time conduct a cross-check of the instrument readings, thanks to which it is possible to detect a malfunction in one of the instruments, if this is the case to be ^{[21] [22]} .

When the N454PA board crossed the glide path, it did not long remain at the same height, which is why it was above the glide path. The commander moved the plane to a descent and, after 1,000 feet (300 m ) from the intersection point, entered the glide path. The instrument speed at this time fluctuated around 160 kts (300 km / h), while the descent path was not stable, which can be explained by the effect of rain and wind. Tests have shown that very heavy rain can lead to an increase in the vertical speed of descent by 600 feet per minute (3 m / s), but the testimony of the survivors showed that the plane was not in the area of ​​heavy rain before the collision with the trees. Thus, the fluctuations of the aircraft during a descent can be explained by the influence of the winds. Also, due to changes in the wind, the indications of the speed indicator from the co-pilot could deviate up to 9 knots (17 km / h), but, according to the commission, this did not play a significant role given the current wind forecast ^[22] .

Fifty seconds before the collision, the liner flew over the rugged terrain of Logotala Hill ( Logotala Hill ), when it collided with an increased head wind and / or got into the ascending air flow. Air speed has increased dramatically to about 160 knots (300 km / h), and the vertical speed on the contrary decreased, because of which the plane now began to leave above the glide path. Trying to rectify the situation, the crew reduced the engine power. The effect of the wind shear lasted for about 25 seconds. Then the airliner left the area Logotaly, while the positive vertical component disappeared, but the engine power is now below the permissible. As a result, the vertical descent rate increased to about 1500 feet per minute (457 m / min or 7.6 m / s) 16 seconds before the crash ^[22] . According to the commission, the crew commander took timely action when the speed of the fall slowed down due to the wind, but missed the moment when the wind stopped, and taking into account the low thrust, this led to a rapid increase in the speed of the decline. There were 12 seconds left to correct the situation, but the pilots did not increase the power of the engines, nor did they deflect the steering wheel “on themselves” ^[22] .

The crew seemed unaware of the high speed of descent and the impending catastrophe. It is likely that the commander at this time was not looking at the instruments, but at the area under them, trying to find his way. But the decline occurred at night over a territory where there was no coverage (known as the Blackhole ). Heavy rain had already passed over the airfield and was heading in the direction of approach when the co-pilot reported on the observation of the strip. The pilots stopped looking at the instrument readings in the cockpit and switched to visual flight too early, because in this case it was impossible to detect changes in the descent path. Moreover, since there were no visual landmarks outside, it was impossible to notice and correct the high vertical speed in a timely manner. To facilitate the implementation of the visual approach, the airport was equipped with a visual approach indication system VASI, which was operating at the time of the crash. But there is no evidence that its lights were seen from the plane, because they could obscure the wall of the oncoming rain. However, even in such conditions, the approach could continue, as the pilots saw the approach lights and the end of the strip ^[23] .

When the co-pilot told the commander that they were following a slightly higher glide path, it is likely that he did not see the VASI lights. In addition, the right-hand radio receiver was not tuned to the frequency of the ILS radio beacon, due to which the co-pilot did not know the exact position of the aircraft on the glide path. Only when the radio altimeter warnings were heard, and only a few seconds remained before the crash, the co-pilot looked at the instruments and saw that in fact the airliner should be at the minimum allowable height and at a speed of only 140 knots (260 km / h). From this it was concluded that the co-pilot did not observe the VASI lights. If the commander observed these lights, he would have had time to understand that the plane was below the glide path, then look at the instruments in the cockpit, and then take timely measures to correct the situation. However, when the co-pilot said that they were above the glide, then the airliner went into a rapid decline, and the vertical speed reached 1500 feet (460 m ) per minute. In this case, no one in the cockpit paid attention to the readings of the instruments, indicating a rapid decline, and did not warn the commander. As a result, the commander did not know about the real situation, and the engine power was increased only a few seconds before the collision. Observe the commander of the testimony of the VASI system, he would have noticed that the plane actually followed the final 15 seconds under the glide path, and the last 8 seconds followed a safe altitude ^[24] .

Based on the analysis of the flight trajectory of flight 806, the commission came to the conclusion that the situation would have developed when the plane was at an altitude of 178 feet (54 m ) above the trees, while the commander would have seen the VASI lights. First of all, for about a second, he reads the readings of the lights, and then, for about a second and a half, he interprets the situation that the plane is below the permissible. The vertical descent rate at that moment was 25 feet (7.6 m ) per second, and therefore the Boeing is reduced by about 80 feet (24 m ) during this time interval. Next, the pilots are pulling the steering wheel "towards themselves", thereby raising the nose of the liner at a speed of 4 ° / s, as a result of which the latter, with a 1.5-fold overload, comes out of the descent and goes into climb. Since 2.5 seconds is considered normal for the concept of indications of indication lights and for taking timely action, then, having dropped by a total of 133 feet (41 m ), the car goes into horizontal flight 35 feet (11 m ) above the trees. It is worth noting that with such a maneuver, there will also be a decrease in flight speed, even if the engines are switched to maximum power. Therefore, if suddenly at this moment the headwind speed drops, the liner still crashes into the trees. But, according to the commission, the wind shear, which Boeing encountered at the time of the disaster, was caused not only by the wind, but also by the height, which caused the influence of the nearby land. Thus, the commission came to the conclusion that the crew still had the opportunity to transfer their aircraft to horizontal flight ^{[24] [25]} .

To some extent, the rain storm contributed to the catastrophe, which created the illusion that the horizon is lower than it actually is. As a result, the pilots mistakenly assumed that the plane was flying with a higher nose and at a higher altitude, because they lowered their nose and reduced engine power. But if the pilots watched the instruments at this time, they should have noticed that they actually follow 500 feet (150 m ) below the height of the entrance to the glide path, and the entry into the glide path happened 180 feet (55 m ) below it. The co-pilot checked the altimeter settings about 2 minutes and 24 seconds before the crash, but did not name the actual altitude. Only after a warning from the radio altimeter, the co-pilot spoke about the dangerous altitude, and after three seconds the commander muttered about it. After five seconds, the noise of the increasing engine power was recorded on the voice recorder ^[25] .

Based on the above, it can be determined that the creation of a catastrophic situation began 15 seconds before hitting the trees, when the plane began to descend at an average vertical speed well above 1000 feet (300 m ) per minute - the maximum set for this airport. At the same time, the airliner entered the glide path 138 feet (42 m ) below the set height and even briefly followed the glide path, after which it dropped below it. The pilots could not visually control the position of the liner on the glide path, since the VASI indication lights at that time were most likely closed by rain. Although it is likely that these lights did not work at all due to a power failure at the airport ^[26] .

Reasons to

On November 8, 1974, that is, already 10 months after the catastrophe, the National Transport Safety Board (NTSB) issued an AAR-74-15 report , according to which the crew was responsible for the crash, because after passing the height of the decision, he did not correct the high speed reduction. During the landing approach, the pilots switched from instrument flight to visual flight and now did not properly monitor the instrument readings. But now, in the conditions of rain, a visual illusion arose, as a result of which the pilots thought that they were much higher than what was needed and closer to the airport, so the speed of descent was increased. Due to the lack of interaction between people in the cockpit, the other two members of the flight crew did not control the instrument readings and did not warn in time about the high speed of descent and low altitude. The visual approach indication system (VASI) functioned normally, but the crew was not guided by its testimony ^[29] .

Further tests, as well as a more thorough analysis of the tragedy of flight 806, made it possible to more accurately determine the causes. As a result, on October 6, 1977, the NTSB issued the AAR-77-07 report , which completely replaced the AAR-74-15 report three years ago. Now the commission has come to the conclusion that the weather has become another important factor in the crash. The high vertical speed was the result of the aircraft being hit by wind shear, in which there were horizontal and vertical air currents, the latter being caused by rugged terrain. As a result, the liner actually began to go above the glide, as the crew tried to correct, but was disoriented during a night flight in the rain and over completely dark terrain. At the same time, until recently the crew did not pay attention to the readings of the instruments, with the result that within 15 seconds the descent rate exceeded the maximum allowed. The pilots could not be guided by the testimony of the VASI system, since it could have been hidden due to heavy rain at the airport} ^{[28] [20]} .

Свои замечания к отчёту 1977 года высказал Кей Бейли ( англ. Kay Bailey ), который исполнял обязанности председателя комиссии. По его мнению, основным фактором катастрофы стал именно сдвиг ветра, особенно в сочетании с сильным дождём. Ошибка экипажа, который не заметил высокую скорость снижения, стала второстепенным фактором, так как экипаж был значительно дезориентирован при полёте над местностью, где отсутствовали визуальные ориентиры, а из-за дождя возникла иллюзия относительно местонахождения самолёта в пространстве, при этом отсутствовал надлежащий контроль за показаниями приборов. Таким образом, по мнению Бейли, причиной катастрофы стал сдвиг ветра в условиях отсутствия своевременной реакции экипажа ^[30] .

Comments

Sources

• Pan American World Airways, Inc., Boeing 707-321-B, N454PA, Pago Pago, American Samoa, January 30, 1974. (англ.) . National Transport Safety Bureau (6 October 1977). Дата обращения 1 ноября 2014.