Scandinavian Airlines system flight 933
| Scandinavian Airlines system flight 933 | |
|---|---|
 The unlucky machine LN-MOO in 1967 at Stockholm-Arlanda Airport |
|
| Accident summary | |
| Accident type | Controlled flight into water by distracting the crew |
| place |
Santa Monica Bay , seven miles from Los Angeles , California , United States
|
| date | January 13, 1969 |
| Fatalities | 15th |
| Survivors | 30th |
| Injured | 17th |
| Aircraft | |
| Aircraft type |
Douglas DC-8-62
|
| operator |
   Scandinavian Airlines System
|
| Mark |
LN-MOO
|
| Departure airport |
Copenhagen Airport , Denmark
|
| Stopover |
Seattle-Tacoma Airport , United States
|
| Destination airport |
Los Angeles Airport , United States
|
| Passengers | 36 |
| crew | 9 |
| Lists of aviation accidents | |
On January 13, 1969, a Douglas DC-8-62 of the airline Scandinavian Airlines System had an accident on Scandinavian Airlines System flight 933 (flight number SK933 ) . The machine, which is on a flight from Copenhagen Airport to Los Angeles International Airport with a stopover at the Seattle Center was, was it due to a pilot error shortly before the scheduled landing into the waters of Santa Monica Bay off the coast of California directed ( controlled flight into terrain ), killing 15 people.
plane
The machine that crashed was a two and a half year old Douglas DC-8-62, which was assembled at the Douglas plant in Long Beach , California and which was rolled out on June 28, 1966.
The first flight of the DC-8 was carried out on August 29, 1966, the delivery to the SAS Scandinavian Airlines took place on June 20, 1967. The machine was certified with the Norwegian aircraft registration LN-MOO and was given the name Sverre Viking . The aircraft had the factory number 45822, it was the 270th Douglas DC-8 from ongoing production. The DC-8 was equipped with four Pratt & Whitney JT3D-3B engines. The last scheduled maintenance was carried out on April 3, 1968. At the time of the accident, the machine had completed 6,950 flight hours.
crew
At the time of the accident, there was a nine-person crew on board who had boarded at Seattle-Tacoma Airport. The boarding crew had completed their last flight on January 11 and had a 48-hour rest period before their assignment on Flight 933. The crew consisted of a master, a first officer, a flight engineer and six flight attendants. The captain of the machine was the 50-year-old Briton Kenneth Davies, who had flown for the SAS since 1948 and had previously been a member of the RAF Coastal Command . During his SAS career, he had 11,135 hours of flight experience, including 800 on the DC-8. First officer was the 40-year-old Ingvar Hansson, who had been employed by the SAS since 1957. He had 5814 hours of flight experience, including 973 on the DC-8. 32-year-old flight engineer Ake Ingvar Andersson had worked for the SAS since 1967 and since then had completed his entire 985 hours of flight experience on the DC-8. All three pilots had valid flight licenses and health certificates and had received extensive training.
Flight history
Flight 933 was an international scheduled flight from Copenhagen to Los Angeles. The flight to the stopover at Seattle-Tacoma Airport, where the aircraft was refueled and a new crew boarded, went without any special incidents. The flight time to Los Angeles should be 2 hours and 16 minutes. The machine has been properly defrosted and the altimeters have been adjusted. The plane left Seattle at 3:46 p.m. local time, 71 minutes late compared to the flight schedule. The first officer steered the machine. The autopilot was used for the climb as well as the flight at cruising altitude.
Shortly after 5:20 p.m., the Scandinavian Airlines flight controller informed the crew that the weather conditions at Los Angeles Airport were appropriate for a landing. At 5:32 p.m., the crew contacted the air traffic control at Los Angeles Airport and received instructions to fly a holding pattern over Bakersfield . The crew confirmed that the holding pattern was flying at 1747. At 18:39 the crew received clearance to initiate the descent via Fillmore and then to remain at an altitude of 1500 feet (approx. 460 meters) and to fly to the waypoint Westlake, which was not yet shown on the flight charts.
At around 7 p.m. there were isolated clouds in the sky at a height of 300 meters, the cloud cover was at a height of 500 meters. The visibility was 2.5 nautical miles (approx. 4.6 kilometers) with light rain and fog. The sky was dark and the crew could not make out any visible reference points. The descent was controlled by the vertical speed controller of the autopilot, while the flight altitude to be reached was preset manually. While leaving the autopilot activated, the pilots reduced the airspeed to 160 knots (approx. 300 km / h) at 19:07 on the instructions of air traffic control. At this point in time, the crew was completing the checklist for the approach. The master interrupted this process after looking at the radio altimeter he noticed that the aircraft had already sunk below the intended flight altitude. The master wanted to observe the further flight behavior of the machine during the descent. At 7:11 p.m. the crew received clearance to fly a 180 degree turn and to descend to 1000 feet (approx. 300 meters) and maintain this altitude. Both receivers of the navigation system have been set to the ILS frequency.
At 19:17, the air traffic controller asked the crew of the DC-8 to reduce their speed again to 153 knots (approx. 283 km / h), which they confirmed. At 19:19 he gave clearance for runway 07R. At that time, the first officer believed that the machine was 14 nautical miles (approx. 26 kilometers) from the rotary radio beacon, while the master believed that the distance was 11 to 12 nautical miles (approx. 20/22 kilometers). The first officer turned off the autopilot. The captain extended the landing gear and the first officer asked that the landing checklist be completed. This process was interrupted again by radio communication and further actions in the cockpit. The machine continued to sink to an altitude of 576 feet (176 meters).
In front of the DC-8 was a Cessna 177 Cardinal with flight number 67T , which was also making an approach and flying at a speed of 110 knots (approx. 200 km / h). All radio communication between the SK933, 67T and air traffic control took place over the same radio frequency. At 19:19, air traffic control asked the SK933 crew to reduce their speed further and watch out for the Cessna. The pilots reduced the speed to 126 knots (approx. 233 km / h). This speed requires the lifting devices to be extended , but this was not done. The nose gear display in the cockpit indicated an unsafe position. If the buoyancy aids were extended but the landing gear retracted, a warning tone would sound that could not be turned off without retracting the buoyancy aids. The captain extended the landing gear again, but an unsafe position was still indicated. The first officer believes, however, that the buoyancy aids have been extended.
At 7:20 p.m., the flight engineer carried out a system check first offhand and then using a manual. At the same time, the captain informed air traffic control that there were problems with the landing gear and that a missed approach with a return to Las Vegas airport would have to be carried out if the problems could not be resolved before the minimum altitude was reached. Finally, the flight engineer stepped down to the cockpit's viewing port and found that the landing gear was extended and locked. After he informed the master about this, he used the buoyancy aids to the full. At this point the machine was flying at an altitude of 1000 feet (approximately 300 meters).
Minutes before impact, the aircraft was at an altitude of 3,050 feet (930 meters). It sank to an altitude of 2,200 feet (670 meters) over the next 26 seconds, where it remained for 16 seconds, and finally sank to sea level in 1 minute and 16 seconds. Since the crew was busy with the landing gear position and the control lamps in the cockpit, they overlooked the descent in which the machine was located. The captain only registered this when the altimeter was nearing zero. He increased the thrust, but before he could perform the interception maneuver, the machine hit the water. The impact took place at 19:21 local time, in international waters of Santa Monica Bay , 6 nautical miles west of Los Angeles Airport, at a point where the water depth is 110 meters. The crew did not mention any unusual rate of descent before the impact, nor were there any warnings in the cockpit, with the exception of an indicator light which came on shortly before the impact and signaled a course difference.
The engine hit the water stern first. As a result, the hull broke in three parts. The largest part was the 26 meter long nose section, from the aircraft nose to the wing trailing edge. This part floated over the water for more than 24 hours. The middle part was the 13 meter long fuselage section from the wing trailing edge to the rear pressure bulkhead. The rear part consisted of the rear of the machine with the horizontal and vertical stabilizers. The engines and the landing gear tore off the machine on impact.
Rescue and recovery operation
Three crew members and 12 passengers were killed in the accident. Four of the victims were recovered, with a death by drowning diagnosed. The remaining 11 people were never found and pronounced dead. Eleven passengers and the remaining six crew members were injured, while 13 passengers were uninjured. A total of 30 people survived the accident.
The passengers were evenly distributed within the machine, the chances of survival of the passengers in the front part of the machine were higher than those of the passengers in the middle part. The three surviving members of the cabin crew, an out-of-service captain and a flight attendant evacuated the passengers first in the direction of the wings and finally in lifeboats.
While the survivors boarded the first two lifeboats, they were tied together and the passengers rowed from the wing towards the nose of the aircraft. One of the boats scratched a protruding piece of metal and lost its air, causing people from the boat to fall into the water. Other passengers started a lifeboat from the starboard side, which, however, was also pierced.
The US Coast Guard started a rescue operation immediately after the accident. It took the rescue teams about 45 to 60 minutes to get to the scene of the accident. Despite the deployment in a winter month with appropriate water temperatures, 30 people were rescued. The Coast Guard searched the area for survivors for hours, until a point in time when no more bodies could be found and the finding of survivors was no longer expected .
The front part of the wreck was towed to Malibu , where it initially sank. It was later lifted and taken to Long Beach Naval Shipyard for examination . All flight instruments could be recovered. The other two parts of the wreck were never recovered.
Accident investigation
Since the accident occurred in international waters, the investigation was carried out in accordance with the provisions of the 1944 Convention on International Civil Aviation . The Norwegian government asked the National Transportation Safety Board to conduct the investigation. The maintenance documents have been checked by the Norwegian Transport Safety Authority. The final report was published on July 1, 1970, after a 534-day investigation.
All navigation facilities at Los Angeles Airport were checked. It was found that they were all working perfectly at the time of the accident. Flight data recorders and voice recorders were recovered from the sea floor using an ROV . They survived the accident unscathed. Test flights and simulator tests were carried out, during which the course of the accident could be reconstructed. When it was determined that the machine was airworthy, the investigation focused on the actions of the cockpit crew.
Cause of accident
The investigations uncovered a number of events which, together, had led to a breakdown in crew resource management . Two incidents had caused the flight to be delayed, the de-icing at Seattle-Tacoma Airport and the hold over Bakersfield. Together with the wind conditions in flight, this caused the machine to be three hours late. This led the captain to consider returning to Las Vegas. The first pilot error occurred when the first officer incorrectly set his altimeter at the beginning of the descent. The difference to the altitude display of the captain was never noticed.
During clearance for landing, air traffic control used ambiguous terms that did not meet the usual standards. The master had made a VOR approach without informing air traffic control. None of the pilots had ever performed an instrument approach on runway 07R as they usually approached runway 25. Another factor was air traffic control's requirement to fly the DC-8 at the slowest safe airspeed when approaching the Cessna.
The commission of inquiry identified the actions as measures to avoid further delays on a flight that was already significantly delayed. The decision to let the machine sink at five meters per second was assessed as understandable under the prevailing conditions. However, while the master turned to the problem with the nose landing gear, the machine sank at a speed of 10 meters per second for 26 seconds, then remained at a stable altitude for 16 seconds and then sank again at 8.6 meters per second until impact. The actions of the master distracted the first officer from his actual task of flying the machine. The retraction and extension of the landing gear as well as the late extension of the buoyancy aids made his task of controlling altitude and airspeed more difficult. When the buoyancy aids were fully deployed, the master had also failed to inform the first officer.
Because of the problems with the nose landing gear and the low approach speed, the captain had considered making a missed approach and returning to Las Vegas airport. The commission of inquiry was of the opinion that the master had failed to properly monitor the approach and that the crew resource management had collapsed. The master neglected to properly instruct the first officer. He also did not follow instructions given by the first officer. This ultimately also distracted the first officer from his task of observing the cockpit instruments. The situation was made worse when the crew tried to reduce the speed to 126 knots (approx. 233 km / h) while the machine was not configured correctly for this speed. These factors had led to a situation in which neither pilot paid any attention to the altitude. The map for the approach was also flawed because it did not indicate the minimum altitude for the junction to be approached.
The investigative commission classified the accident as "survivable" because the impact forces were distributed differently along the fuselage. The fact that the machine hit the stern first was due to the first officer's attempt to pull the machine up at the last moment. Most of the deaths had occurred because passengers were trapped in the sinking hull parts.
context
The incident was the twentieth total loss of a Douglas DC-8 and the first of the 60 series of the DC-8 . It was the fourth of five fatal accidents involving the SAS, only to be followed by the Milan Linate accident in 2001.
Only five days after the flight accident, the DC-8 crashed in the United Air Lines Flight 266 , a Boeing 727 of United Airlines also in the Santa Monica Bay.
Similar accidents
Individual evidence
- ↑ Aircraft accident data and report DC-8-62 LN-MOO in the Aviation Safety Network , accessed on April 3, 2019.
- ↑ Operating history DC-8-62, LN-MOO Planespotters (English), accessed on March 25, 2019.
- ↑ a b c d e f g h i j k l m n o p q r s t u v National Transportation Safety Board : Aircraft Accident Report Scandinavian Airlines System McDonnell Douglas DC-8-62, LN-MOO (Norwegian registry) in Santa Monica Bay near Los Angeles, California January 13, 1969 . July 1, 1970. Archived from the original on June 13, 2006.
Coordinates: 33 ° 55 ′ 14 " N , 118 ° 31 ′ 58" W.