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Tenerife Source: The Aviation Geek Club 2019, image Source: flighttradar24…
Source: The Aviation Geek Club 2019
What Happened?
Not enough parking for planes so taxiway was being used to park - KLM4805 was parked in front of PAA1736
KLM4805 allowed passengers to disembark, PAA1736 kept passengers onboard during delay. KLM also requests to refuel during the delay.
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KLM4805 & PAA1736 diverted to Los Rodeos Airport, Tenerife - KLM landing at 1:38pm, PAA at 2:15pm.
ATC requests KLM4805 to taxi back down takeoff runway and make 180 turn at end and wait for instruction
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PAA1736 ready to take off but cannot get past KLM4805 flight on taxiway and must wait. Refueling takes longer than expected causing further delay
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Two flights destined for Las Palmas Airport, March 27 1977
ATC instructs PAA1736 to follow KLM down takeoff runway and leave on taxiway C3 to use parallel taxiway for remainder of taxi
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5:06pm - KLM4805 collides with PAA1736 during its takeoff stage on runway causing a total loss of 583 lives
Weather conditions have got worse with rain and heavy fog patches setting in causing periods of reduced visibility
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Why it Happened?
Communications
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Two simultaneous transmissions made from ATC and PAA not clearly received by KLM at a critical stage.
Confusion which exit PAA was to take from runway - ATC instructed PAA to exit runway on third intersection but travelled past C-3 exit as C-4 was a 45 degree turn allowing the 747 to make the exit
KLM Flight Engineer asks Captain "Is he not clear then, that Pan Am?" suggesting communications from PAA being on the runway was heard by KLM.
Inadequate language used by KLM co-pilot stating the phrase "we are now at take-off" which was not clearly understood.
Environment
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PAA had trouble identifying which taxiway to exit the runway due to unfamiliar environment and fog. PAA travelled past exit instructed by ATC due to angle of turn.
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Unplanned Diversion
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Limited space at Los Rodeos Airport to handle parking additional diverted flights - planes parked on taxiway
Delay
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PAA captain maintains passengers onboard and when Las Palmas airport reopened, PAA was unable to pass by KLM plane parked in front. KLM also refuels adding further delay. KLM takeoff procedures do not commence until 4:56pm.
Limitation of duty time on KLM crew - captain aware that he had limited time to takeoff to meet company duty time requirements or risk further delays and cancellations.
System
Parts
System relies on flight crew to clearly communicate with ATC and follow instructions given. KLM Captain was not given clearance to takeoff but commenced takeoff while runway was not confirmed clear.
Neither Captain knew how long the delay would be - PAA decided to keep passengers onboard to takeoff as soon as clearance was given / KLM decided to allow passengers to disembark and bus to the terminal which caused delay when some passengers were late to re-board.
KLM captain decided to refuel during delay to save time on the turn around at Las Palmes but it takes longer than expected and delays departure in Los Rodeos further as well as unintentionally adding maximum weight during takeoff attempt.
Nature of the System
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Captains status and high regard in the cockpit presented reluctance from crew to challenge decisions and actions of the Captain.
This scenario was running under a Mechanical Human-Machine System with flight crews manipulating the control of the powered aircrafts and directed by human Air Traffic Control.
Design Failures
Latent failures
KLM Captain spending extensive period training in simulators and following own protocols for takeoff - simulators did not include following ATC guidance and latent standard operational failures had begun to be developed.
Aviation language used by flight crews and ATC open to misinterpretation with the use of the word takeoff for clearance after takeoff
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Processes and Procedures
Planes unable to use normal taxiway due to congestion and back track along takeoff runway against usual ATC standard procedures.
KLM Captain did not follow standard operating procedure for gaining takeoff clearance - crew did not intervene or question the Captains decision.
Dutch regulations introduced for KLM crew limits on duty time procedures influenced decisions and actions
System Life Cycle
Los Rodeos Airport
Commission
Runway length extended multiple times, navigational aids installed in line with developments of aircraft and apron extended to cater for Boeing 747s
Design
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High altitude in a hollow between mountains, airport frequently experiences low lying clouds but no ground radar system installed
Operation
Operates to a lower volume of air traffic but has domestic and international capabilities under ATC.
Another fatal flight destined for Los Rodeos crashed on decent due to local terrain and conditions killing 146 people.
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Aircraft
Design
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Flying further, faster and introduced luxury classes of air travel
Bigger, heavier aircraft requiring longer runways, better brakes, stronger landing gear, additional engines and more fuel
Commission
Training pilots to competently fly bigger, heavier aircrafts
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Workplace
Workplace factors
Airport
Los Rodeos is a smaller airport - 1 taxiway, 1 takeoff runway
Las Palmas is a larger airport - closed due to bomb explosion and flights diverted to nearby Los Rodeos airport in Tenerife
Los Rodeos not equipped to handle the additional flights - planes being parked on the taxiway that created taxiing issues - takeoff runway being used to back track flights for takeoff.
PAA unable to pass by KLM plane parked in front when Las Palmas reopened causing further delay until KLM was ready to depart over 2 hours later.
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KLM Captain
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During delay, chose to refuel with 55,500L to enable faster transit through Las Palmes and make return to Amsterdam within limits of duty.
KLM crew limits on duty time - if the KLM did not depart by a specified time, the flight would be cancelled and another crew flown in from Amsterdam causing further significant delays & costs.
First flight in 3 months after operating and training only in flight simulators with no ATC and developing habits of takeoff without gaining ATC clearance - limited recent experience flying the line.
Las Palmas reopens but refueling takes longer than expected and causes further delay. KLM fuel load would cause a devastating fire after impact.
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ATC
ATC local language of Spanish communicating in Aviation English to PAA American crew and KLM Dutch crew - accent issues obvious in ATC instruction for PAA to confirm exit.water
ATC instructed PAA to make exit at third intersection C-3 which required a 148 degree turn - PAA travelled past C-3 and intended to exit C-4 which is a 45 degree turn for the Boeing 747
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Work Environment
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ATC at Los Rodeos not use to handling the additional air traffic management due to diverted flights.
KLM crew time pressures from Dutch regulations of limit on duty time to complete the flight and make the return to Amsterdam
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Equipment Design
Two of the largest commercial planes being used at the time - KLM4805 Boeing 747-206B carrying 248 people / PAA1736 Boeing 747-121 carrying 396 people.
Two critical calls made by ATC & PAA on same frequency - ATC advising KLM to standby for takeoff / PAA advising it was not clear of runway - neither heard by KLM crew and only a sequel was received due to the calls made at the same time.
When KLM crew get a visual of PAA still on runway, it's to late to stop the Boeing 747 in time so they continue to attempt to takeoff over PAA and just get off the ground but not soon enough and make fatal contact.
PAA sights KLM travelling towards them, Captain attempts to full throttle and turn off the runway but is unable to maneuver such a big aircraft quick enough to avoid impact.
Ground radar not available at Los Rodeos for ATC to know the locations of planes on the ground when visibility is limited due to weather conditions.
People
Individual factors
Competency
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Captains of both flights accomplished pilots / KLM Captain with 1545 hours experience flying a Boeing 747 - PAA Captain with 564 hours experience flying a Boeing 747
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Knowledge
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Both flight crews included an experienced Captain, Co-Pilot and Flight Engineer
Management
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Job Design
Boeing 747 Captain were very highly regarded and rarely was it accepted for flight crew to question authority of the much experienced Captain which potentially created a non-collaborative environment in the cockpit.
Pilots are trained to make split second decisions with the safety of all passengers in mind. Were the decisions of the KLM Captain made with the safety of his 234 passengers and 13 other crew members in mind.
Information Transfer
Both flight crews made assumptions and took action on what they believed correct against instruction - KLM commenced takeoff prior to getting ATC clearance / PAA instructed to take third intersection but continued past to make more suitable exit at C-4.
ATC had to give clearance to KLM to takeoff - KLM Captain commenced takeoff procedure without clearance and KLM flight crew did not intervene.
KLM Captain head of flight training dept. so other crew members may have been intimidated to question against his actions.
Source: flighttradar24 2006
Source: PBS 2006
Source: The Aviation Geek Club 2019
Source: flickr 2010