View source for Scandinavian Airlines System Flight 933

{{short description|1969 aviation accident}}
{{Use mdy dates|date=February 2020}}
{{Infobox aircraft occurrence
|occurrence_type = Accident
|name = Scandinavian Airlines System Flight 933
|image = Scandinavian Airlines DC-8-62 LN-MOO.jpg
|caption = LN-MOO, the DC-8 involved, seen in July 1967 at [[Stockholm Arlanda Airport]]
|date = {{Start date|1969|1|13}}
|type = [[Controlled flight into terrain|Controlled flight into water]] caused by [[pilot error]]
|site = [[Santa Monica Bay]], [[Los Angeles]], [[California]], United States
|Coordinates = {{coord|33|55|14|N|118|31|58|W|region:US-CA_type:landmark|display=title,inline}}
|aircraft_type = [[Douglas DC-8#Super 60 Series|Douglas DC-8-62]]
|aircraft_name = ''Sverre Viking''
|origin = [[Copenhagen Airport]]
|stopover = [[Seattle–Tacoma International Airport]]
|destination = [[Los Angeles International Airport]]
|operator = [[Scandinavian Airlines|Scandinavian Airlines System]]
|IATA = SK933
|ICAO = SAS933
|callsign = SCANDINAVIAN 933
|tail_number = LN-MOO
|occupants = 45
|passengers = 36
|crew = 9
|fatalities = 15
|injuries = 17
|survivors = 30
}}

'''Scandinavian Airlines System Flight 933''' was a scheduled international flight from [[Copenhagen Airport|Copenhagen-Kastrup Airport]] ([[Denmark]]) to [[Los Angeles International Airport]] via [[Seattle–Tacoma International Airport|Seattle—Tacoma International Airport]]. On January 13 1969, the [[Douglas DC-8|McDonnell Douglas DC-8]] [[Controlled flight into terrain|crashed]] into [[Santa Monica Bay]] at 19:21, approximately {{convert|6|nmi|km|spell=in}} west of Los Angeles International Airport. The crash into the sea was caused by [[pilot error]] during approach to runway 07R; the pilots were so occupied with the [[nose gear]] light not turning green that they lost awareness of the situation and failed to keep track of their altitude. The [[Scandinavian Airlines System]] (SAS) aircraft had a crew of nine and 36 passengers, of whom 15 died in the accident. 

The crash was similar to [[Eastern Air Lines Flight 401]].
The crash site was in [[international waters]], but the [[National Transportation Safety Board]] carried out an investigation, which was published on July 1, 1970. The report stated the probable cause as improper [[crew resource management]] and stated that the aircraft was fully capable of carrying out the approach and landing. The aircraft was conducting an [[instrument approach]], but was following an unauthorized [[instrument approach#Localizer approach|back course approach]].

==Flight==
The accident aircraft was a [[Douglas DC-8|McDonnell Douglas DC-8-62]] with serial number 45822 and line number 270. It was originally registered in the United States by [[McDonnell Douglas]] as N1501U for testing before delivery to SAS.<ref>Hagby: 326</ref> It was then registered as LN-MOD, but as SAS already had a [[Douglas DC-7]] with that registration, it was re-registered as LN-MOO.<ref>Hagby: 228</ref> The aircraft was registered on June 23, 1967, and named "Sverre Viking" by SAS. Five days later, it was reregistered with [[Norwegian Air Lines]], the Norwegian holding company of the SAS conglomerate, as owner.<ref>Hagby: 230</ref> The DC-8-62 model had been custom-made by McDonnell Douglas for SAS to operate to Los Angeles with a full payload in all wind conditions, although the model was later sold to other airlines as well. SAS took delivery of the first of ten DC-8-62 aircraft in 1967.<ref>Hall: 103–105</ref> "Sverre Viking" had flown 6,948 hours as of January 7 and had met all maintenance requirements. The last overhaul had been carried out on April 3, 1968.<ref name=n13>National Transportation Safety Board: 13</ref>

[[File:Los Angeles Airport, Aerial Overview 1966 JP6194421.jpg|thumb|left|Contemporary view of [[Los Angeles International Airport]]]]
Flight 933 was a regular, international scheduled flight from SAS's main [[airline hub|hub]] at Copenhagen Airport in Denmark to Los Angeles International Airport in [[Los Angeles]], [[California]], in the United States. It had a scheduled stopover at Seattle–Tacoma International Airport in the state of [[Washington (U.S. state)|Washington]] for change of crew and refueling. There were 45 people on board the aircraft at the time of the accident<ref name=n3>National Transportation Safety Board: 3</ref> consisting of 36 passengers and nine crew members.<ref name=n2>National Transportation Safety Board: 2</ref>

The crew outbound from Seattle had flown a flight from Copenhagen on January 11 and had about 48 hours of rest before the flight.<ref name=n3 /> The crew consisted of a [[pilot in command|captain]], a [[first officer (aeronautics)|first officer]], a [[flight engineer]] and six flight attendants.<ref name=n2 /> Captain Kenneth Davies, a 50-year-old Briton, had been employed by SAS since 1948 and had a past in the [[RAF Coastal Command]]. He had flown 11,135 hours with SAS and 900 hours in the DC-8.<ref name=n11>National Transportation Safety Board: 11</ref> First Officer Hans Ingvar Hansson was 40 and had worked for SAS since 1957. He had flown 5,814 hours for the airline, including 973 hours in the DC-8. Flight Engineer Ake Ingvar Andersson, 32, had worked for SAS since 1966. He had flown 985 hours, all of the time on a DC-8. All three had valid certificates, training, and medical checks.<ref name=n12>National Transportation Safety Board: 12</ref>

The [[cabin crew]] consisted of Renning Lenshoj, Arne Roosand, Peter Olssen, Marie Britt Larsson, Susanne Gothberg-Ingeborg, and Ann-Charlotte Jennings. A steward and two stewardesses were killed in the crash, though remains of only one of the three were found.

The flight to Seattle had gone without incident. The landing took place with an [[instrument landing system]] (ILS) approach, with the autopilot coupler being used down to {{convert|100|to|60|m|ft|sp=us}} before a manual completion. The aircraft had three maintenance issues at Seattle consisting of a non-functioning fast–slow airspeed function, low oil on the number one engine, and a non-functioning lavatory light.<ref name=n3 /> The final crew arrived at Seattle–Tacoma an hour before the flight and was given necessary documentation. Flight time was estimated at two hours, 16 minutes. All preflight checks were concluded without discrepancies. The aircraft was [[de-icing|de-iced]] and the altimeters set and cross-checked.<ref>National Transportation Safety Board: 4</ref> The flight departed Seattle at 15:46 [[Pacific Standard Time]] (PST), one hour and eleven minutes after schedule. The first officer was designated as pilot flying. The altimeters were recalibrated and the autopilot was used for the climb and cruise.<ref name=n5>National Transportation Safety Board: 5</ref>

==Approach and landing==
[[File:LAXfromabove.jpg|thumb|Modern aerial view of [[Los Angeles International Airport]]—runway 07R–25L is located to the left and [[Santa Monica Bay]] in the background.]]
Slightly after 17:20, an airline dispatcher confirmed that the weather was suitable at LAX for the landing. The aircraft made contact with [[Los Angeles Air Route Traffic Control Center]] at 17:32 and were told to hold at [[Bakersfield]]. This holding was confirmed at 17:47.<ref name=n5 /> At 18:39, the aircraft was cleared to descend via Fillmore and to keep an altitude of {{convert|1,500|m|ft|sp=us}} via the newly designated Westlake Intersection, which was not yet on the charts. The crew was to conduct a back course ILS at LAX, although they lacked authorization and plates to conduct this.<ref name=n6>National Transportation Safety Board: 6</ref> The weather at 19:00 consisted of scattered clouds at {{convert|300|m|ft|sp=us}}, ceiling-measured {{convert|500|m|ft|sp=us}} overcast, visibility of {{convert|2.5|NM}} and light rain and fog.<ref name=n15>National Transportation Safety Board: 15</ref>

The sky was dark and the pilots lacked any visual ground references. Descent was controlled through the use of the vertical-speed wheel of the autopilot combined with an altitude preselect (which illuminated a light when reaching preselected altitudes) in manual mode. While retaining use of the autopilot, the pilots reduced their speed to {{convert|160|kn|km/h mph}} at the request of air traffic control at 19:07. At this point the pilots were working through the approach [[checklist]].<ref name=n6 /> The captain halted the checklist at the point regarding the radio altimeter as the aircraft was above its operational limit and he wanted to control the plane's operation during further descent. At 19:11, the aircraft received permission to bear 180 degrees and descend to and maintain {{convert|1,000|m|ft|sp=us}} of altitude. Both navigational receivers were tuned to the ILS frequency.<ref name=n7>National Transportation Safety Board: 7</ref>

At 19:17:55, the controller requested that SK933 reduce its speed to {{convert|153|kn}} which was confirmed. At 19:19:05, the controller confirmed that the aircraft was cleared for approach for Runway 07R. At the time, the first officer thought the aircraft was {{convert|14|NM}} from the [[VHF omnidirectional range]] (VOR) transmitter, while the captain thought they were {{convert|11|to|12|NM}} away. The first officer therefore disconnected the autopilot. The captain put the landing gear in down position and the first officer asked for the landing checklist to be completed. This was interrupted by radio traffic and cockpit activities. The aircraft then descended to a minimum altitude of {{convert|176|m|ft}}.<ref name=n7 />

The DC-8 was following a [[Cessna 177 Cardinal]], designated 67T, which was also conducting a back-course approach,<ref name=n7 /> flying at {{convert|110|kn}}. All communication between the two aircraft and air traffic control was occurring on the same frequency. Air traffic control asked SK933 at 19:19:35 to reduce its speed further to take the Cessna into account and the pilots reduced their speed to {{convert|126|kn}}. This speed requires the full extension of the [[flap (aeronautics)|flaps]], but this step was not carried out. The nose gear was showing an unsafe indication; should the flaps be extended fully without the nose gear down, a horn would blow which could not be silenced without retracting the flaps. The captain recycled the gear, but the indicator light still showed an unsafe condition. Meanwhile, the first officer believed that the flaps were fully extended and started reducing speed to {{convert|126|kn}}. After the flight engineer confirmed that the nose gear was down and locked, the captain fully extended the flaps.<ref>National Transportation Safety Board: 8</ref>

The flight engineer carried out a systems check, first from memory and then after consulting the flight manual. At this time, 19:20:42, the captain informed air traffic control that he was experiencing nose-gear problems that, if not resolved by the time the aircraft reached minimum altitude, would force him to cancel the landing and divert to the designated alternate, [[Harry Reid International Airport|McCarran International Airport]] (now Harry Reid International Airport) in [[Las Vegas]]. This was the last transmission from Flight 933. The flight engineer conducted a manual check of the landing gear from the cockpit peephole confirming it was down and locked. At this time, the aircraft had an elevation of {{convert|300|m|ft|sp=us}}. The lowest speed that the pilots remembered was {{convert|130|kn}} with full flap extension.<ref name=n9>National Transportation Safety Board: 9</ref>

Minutes before impact, the aircraft had an altitude of {{convert|930|m|ft|sp=us}}. It descended to {{convert|670|m|ft|sp=us}} in the next 26 seconds, leveled for 16 seconds, then descended to [[sea level]] in one minute and 16 seconds.<ref name=n17>National Transportation Safety Board: 17</ref> The pilots did not have control over the rate of descent and the next thing remembered by the first officer was seeing the altimeter approaching zero. He attempted to pull up through back pressure and adding power, but the aircraft hit the water before he was able to execute this maneuver. The impact took place at 19:21:30 PST (03:21:30 on January 14 [[Coordinated Universal Time]]) in Santa Monica Bay, about {{convert|6|NM}} west of LAX, in [[international waters]] where the sea is {{convert|110|m|ft|sp=us}} deep. The crew did not recall any unusual sink rate, buffeting, or yawing, nor were there any instrument warnings except a last-moment flashing of the heading-difference light.<ref name=n9 />

The aircraft hit the water with the tail first.<ref name=n20>National Transportation Safety Board: 20</ref> The impact caused the fuselage to break into three main parts. The largest was the {{convert|26|m|ft|adj=on|sp=us}} forward section of the aircraft from the nose to the trailing edge of the wings. It remained afloat after the accident for about twenty hours.<ref name=n17 /> The midsection was {{convert|13|m|ft|sp=us}} long from the trailing edge of the wing to the rear pressure bulkhead. The aft section consisted of the tail cone including all of the [[horizontal stabilizer]]s and the [[vertical stabilizer]]s. The engines and landing gear separated from the aircraft at the time of impact.<ref name=n18>National Transportation Safety Board: 18</ref>

==Rescue and salvage==
Three cabin crew and twelve passengers were killed in the impact. Of these, four were confirmed drowned while eleven were missing and presumed dead. Eleven passengers and the remaining six crew members were injured while thirteen passengers reported no injuries. Thirty people survived the crash.<ref name=n3 /> The passengers were distributed throughout the aircraft,<ref name=n20 /> although there was a slightly higher proportion of survivors forward than aft. The surviving three cabin crew, an off duty captain and flight attendant, evacuated the passengers onto the wings and into liferafts.<ref name=n21>National Transportation Safety Board: 21</ref>

When the first two life rafts were filled, they were tied together and rowed from the port wing toward the nose of the aircraft. One of the rafts scraped against a piece of metal and deflated rapidly with its passengers falling into the water. Other passengers launched a life raft from the starboard wing, but it was also punctured.<ref name=n21 /> A [[search and rescue]] mission was quickly initiated by the [[United States Coast Guard]].<ref name="harrison">{{cite web |last=Harrison |first=Scott |date=May 10, 2011 |title=SAS jetliner crashes off L.A: coast, 1969 |url=http://framework.latimes.com/2011/05/10/sas-jetliner-crashes/#/0 |url-status=dead |archive-url=https://web.archive.org/web/20110513230208/http://framework.latimes.com/2011/05/10/sas-jetliner-crashes/#/0 |archive-date=May 13, 2011 |access-date=April 16, 2014 |work=[[Los Angeles Times]]}}</ref> It took between 45 and 60 minutes before the rescue team was able to pick up the survivors.<ref name=n21 /> The Coast Guard stayed for hours searching for survivors.<ref name=harrison />

The forward part of the aircraft was towed toward [[Malibu Beach]] where it sank. It was later raised and brought to [[Long Beach Naval Shipyard|Long Beach Terminal Island Naval Shipyard]] for investigation. All flight instruments were recovered.<ref name=n17 /> The remaining other two sections, along with the engines and landing gear, were not recovered.<ref name=n18 />

==Investigation==
Because the crash took place in international waters, the investigation was carried out in accordance with the [[Convention on International Civil Aviation]]. The [[Government of Norway]] requested that the investigation be carried out by the United States' [[National Transportation Safety Board]]. The maintenance records were investigated by Norway's [[Accident Investigation Board Norway|Aviation Accident Commission]].<ref name=n10>National Transportation Safety Board: 10</ref> The final report from the board was issued on July 1, 1970, after 534 days of investigation.<ref name=n35>National Transportation Safety Board: 35</ref>

Flight 933 was the 20th hull loss to a DC-8; it was at the time the tenth-deadliest accident of the type and remains the twentieth-deadliest.<ref>{{cite web |url= https://asn.flightsafety.org/asndb/331640 |title= Monday 13 January 1969 |publisher=[[Aviation Safety Network]] |access-date=April 16, 2014}}</ref> It was SAS's third fatal crash, but the airline would not experience another until the [[2001 Linate Airport runway collision]] of 2001.<ref>{{cite web |url= https://asn.flightsafety.org/database/operators/5415 |title=Scandinavian Airlines System – SAS |publisher=[[Aviation Safety Network]] |access-date=April 16, 2014}}</ref>

All [[navigational aid]] systems at LAX were checked and found to be working at the time of the accident.<ref name=n16>National Transportation Safety Board: 16</ref> The [[flight recorder]] was recovered using a [[remotely operated underwater vehicle]] and found to be intact.<ref name=n17 /> Flights and simulator tests were carried out by SAS, confirming that the recorded data could be simulated in an appropriate manner on schedule.<ref name= n22>National Transportation Safety Board: 22</ref> As the aircraft was found airworthy and able to be flown, the bulk of the work of the investigation commission focused on operational procedures.<ref name=n24>National Transportation Safety Board: 24</ref>

==Cause==
The accident was caused through a series of events which, although not in themselves sufficient to cause the crash, [[Swiss cheese model|combined]] to create a breakdown in [[crew resource management]]. The flight experienced two delays (de-icing at Seattle–Tacoma and holding at Bakersfield), which along with wind speeds increased the flight time by nearly three hours.<ref name=n24 /> This caused the captain to consider diverting to Las Vegas. The first pilot error occurred when the first officer incorrectly set his altimeter when the descent started. The difference between his and the captain's altimeter was never noticed.<ref name=n25>National Transportation Safety Board: 25</ref>

Upon receiving clearance, a non-standard terminology was used by air-traffic control. As he did not have authorization to use a localizer back-course approach, the captain should have requested a different approach. Instead, the crew opted to conduct a VOR approach without informing air traffic control. Neither pilot had carried out instrument approach and landing at runway 07R making them less familiar with this than their commonly used Runway 25.<ref name=n25 /> Another factor was that the SAS aircraft was forced to operate at the lowest-permissible safe speeds while closing in on the Cessna.<ref name=n26>National Transportation Safety Board: 26</ref>

The commission interpreted several of these actions as taking shortcuts to avoid further delays on an already severely delayed flight. They regarded the decision to descend at 5&nbsp;meters per second (1,000&nbsp;fpm) as reasonable given the conditions. However, as the first officer focused on the nose gear issue, the aircraft actually experienced a descent of 10.0&nbsp;meters per second (1,960&nbsp;fpm) for 26 seconds, zero descent for 16 seconds, and then an average descent of 8.6&nbsp;meters per second (1,720&nbsp;fpm) until impact. The first officer was distracted by the captain's dealings with the landing-gear issues, hindering him from primary task: flying the aircraft. The cycling of the landing gear and delay in extending the flaps made speed and altitude control more difficult. The captain also failed to inform the first officer when the flaps were fully extended.<ref name=n27>National Transportation Safety Board: 27</ref>

Both the landing-gear issue and the concerns regarding speed made the captain focus on the possibility of a missed approach and the major inconvenience of diverting to Las Vegas.<ref name=n27 /> It was the commission's impression that the captain failed to properly monitor the approach, and crew resource management broke down. He failed to give proper instructions to the first officer and failed to carry out instructions from the first officer which moved the first officer's attention away from his task of monitoring the flight instruments. The situation was worsened by the crew attempting to fly at {{convert|126|kn}} when the aircraft was not configured for that speed. These factors created a situation in which neither pilot was monitoring the altitude. There was also a shortcoming in the approach chart which did not display a minimum altitude at Del Rey Intersection. This would have given the pilots an opportunity to correct the aircraft's altitude.<ref name=n28>National Transportation Safety Board: 28</ref>

The commission classified the accident as survivable because the impact forces varied along the fuselage. The tail-first impact was caused by the first officer's last-second attempt at raising the aircraft.<ref name=n28 /> Most of the fatalities resulted from people having been trapped in the sinking sections which was caused by the collapsing of the structure after impact. The collapse was caused by the compromise of the tubular integrity which was dependent on the keel beam that had been torn off on impact.<ref name=n29>National Transportation Safety Board: 29</ref>

The nose-gear light indicators were designed to be [[fail safe]] by having two separate light bulbs. This proved to be inadequate, as it was impossible to look through the cover to check whether one of the bulbs had been compromised, meaning that a failure of one bulb would not be detected until both bulbs malfunctioned. The first bulb was thus presumed to have gone inoperative some time before the day of the flight, while the second bulb broke during Flight 933.<ref name= n30>National Transportation Safety Board: 30</ref> The NTSB therefore advised the [[Federal Aviation Administration]] to articulate means to avoid similar compromised fail-safe designs in the future.<ref name=n33>National Transportation Safety Board: 33</ref> Both pilots had minimum-descent altitude light warnings, which were presumed to have given a visual warning, but because of the work overload, neither pilot directed his attention to these alerts.<ref name=n30 />

The investigation commission produced the following conclusion:
{{blockquote| …the probable cause of this accident was the lack of crew coordination and the inadequate monitoring of the aircraft position in space during a critical phase of an instrument landing approach which resulted in an unplanned descent into the water. Contributing to this unplanned descent was an apparent unsafe landing gear condition induced by the design of the landing gear indicator lights and the omission of the minimum crossing altitude at an approach fix depicted on the approach chart.<ref name=n33 />}}

Two similar accidents occurred in the following decade. [[Eastern Air Lines Flight 401]] was a watershed incident in airline safety: on December 29, 1972, its entire flight crew became preoccupied with a burnt-out landing-gear indicator light and failed to notice that the autopilot had inadvertently been disconnected. As a result, the aircraft gradually lost altitude and eventually crashed.<ref>{{cite web | publisher =National Transportation Safety Board | via = Air disaster |title=Eastern Airlines, Inc, L-1011, N310EA, Miami, Florida, December 29, 1972 |date=June 14, 1973 |url= http://www.airdisaster.com/reports/ntsb/AAR73-14.pdf |url-status= usurped |archive-url= https://web.archive.org/web/20121004125402/http://www.airdisaster.com/reports/ntsb/AAR73-14.pdf |archive-date=October 4, 2012 }}</ref> A similar incident occurred on December 28, 1978, when the captain of [[United Airlines Flight 173]] was distracted by a landing-gear issue and did not heed his crewmembers' concerns about the aircraft's fuel level, resulting in an exhaustion of fuel to all engines and a subsequent crash.<ref>{{cite web | publisher =National Transportation Safety Board | via = ERAU |title=United Air Lines, Inc. McDonnell-Douglas DC-8-61, N8082U Portland, Oregon: December 28, 1978 |date=December 28, 1978 |url= http://libraryonline.erau.edu/online-full-text/ntsb/aircraft-accident-reports/AAR79-07.pdf}}</ref>

==See also==
*[[Ansett New Zealand Flight 703]]
*[[Eastern Air Lines Flight 401]]
*[[United Air Lines Flight 266]], a crash which took place not far from where Flight 933 crashed, later the same week

==References==
{{Reflist|30em}}

==Bibliography==
* {{cite book |last=Hagby |first=Kay |title=Fra Nielsen & Winther til Boeing 747 |location=Drammen |publisher=Hagby |language=Norwegian |year=1998 |url=http://www.nb.no/nbsok/nb/e38c175e6746f06628c09886091e4707}}
* {{cite book |title=Luftens Vikingar – en bok om SAS alla flygplan |last=Hall |first=Åke |year=2002 |publisher=Air Historic Research |location=Nässjö |isbn=91-973892-3-4 |language=Swedish}}
* {{cite web |author=National Transportation Safety Board |author-link=National Transportation Safety Board |title=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 |date=July 1, 1970 |url=http://www.airdisaster.com/reports/ntsb/AAR70-14.pdf |url-status=usurped |archive-url=https://web.archive.org/web/20060613212747/http://www.airdisaster.com/reports/ntsb/AAR70-14.pdf |archive-date=June 13, 2006 }} - [https://libraryonline.erau.edu/online-full-text/ntsb/aircraft-accident-reports/AAR70-14.pdf Copy at] [[Embry-Riddle Aeronautical University]]

{{SAS Group}}
{{Aviation accidents and incidents in 1969}}
{{Aviation accidents and incidents in the United States in the 1960s}}
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[[Category:Airliner accidents and incidents in California]]
[[Category:1969 in Los Angeles]]
[[Category:Scandinavian Airlines accidents and incidents|933]]
[[Category:Aviation accidents and incidents in the United States in 1969]]
[[Category:Airliner accidents and incidents involving controlled flight into terrain]]
[[Category:Airliner accidents and incidents caused by instrument failure]]
[[Category:Airliner accidents and incidents caused by pilot error]]
[[Category:Disasters in Los Angeles]]
[[Category:Los Angeles International Airport]]
[[Category:Accidents and incidents involving the Douglas DC-8]]
[[Category:January 1969 in the United States]]
[[Category:Airliner accidents and incidents involving ditching]]