flying an airliner is a complex task it requires highly trained pilots working together to get hundreds of tons of metal and people safely into the air the margin for error is small and when mistakes do happen they can be catastrophic when things go well this complexity looks like clockwork each of the components interlinking seamlessly and taking away the flight the story of Korean airflight 8509 is a dark and complex one its cogs and wheels are psychological technological and even cultural when the Clockwork of this flight burst open just seconds after takeoff on December 22nd 1999 it revealed deepr rooted problems in the aviation industry problems which would need to be reckoned with fast this is the story of Korean Air fight [Music] 8509 it was 20 minutes 7: in the morning at staned airport just Northeast of London as the airport slowly awakened to the day 5,000 km away in Tashkent usbekistan a Korean Air Cargo Boeing 747 Was preparing for departure on board were two pilots a flight engineer and 33 tons of cargo the 19-year-old aircraft had just arrived in from Soul in South Korea and would now be completing the final leg of its Journey to the UK it had received a clean bill of health at Tashkent and the flight was expected to go off without a hitch but we wouldn't be starting the story here if that's what ended up happening mere seconds after takeoff things would start to go wrong on this flight these small imperfections in the Clockwork would set in motion a chain of events which would ultimately Doom the aircraft and its crew at 29 minutes past 12 local time the captain lined the massive aircraft up and Runway 08 left at Tashkent the plan was to depart to the east into the wind and then shortly after takeoff to do a 180° turn to head out west towards Europe the captain pushed the throttles to take off thrust and the heavy plane began accelerating within moments the aircraft took to the sky as the captain climbed he used this instrument here to ensure that he was putting the aircraft in the correct position this instrument is known as the ADI or attitude Direction indicator as the name suggests it tells the pilots their attitude that is their orientation with respect to the Horizon how much they are pointing up or down this symbol here represents the plane its nose here and its wings here while in the background blue represents the sky and brown represents the Earth right now as the aircraft climbed its wings were level and its nose was about 15° above the Horizon if the plane was turning to the right it would look like this to the left would look like this 10° nose up looks like this and 5° nose down down looks like this at night or in clouds Pilots can't see anything out their windows and they rely entirely on this instrument to tell the orientation of their aircraft for this reason the ADI is extremely important so there are three of them in the cockpit one for the captain one for the first officer and one backup each of them operates entirely independently so that a failure in one has no effect on the others shortly after takeoff as the plane pass 1,000 ft the captain began a gentle turn to the right but as he turned something strange happened as the aircraft rolled past 15° of Bank the captain's ADI froze he was still holding his control column to the right and he could see out the window that his plane was clearly still banking further but his instrument had apparently stopped registering the bank he checked the standby ADI and the first officer's ADI and both of these were correctly indic hting the aircraft Bank it wasn't just the captain who had noticed this issue the aircraft itself continuously Compares each of the Adis and it had registered a disparity between the captain's instrument and the other two instruments it put up a flag in front of the captain's ADI and an ARL warning sounded indicating that there was a disagreement between the instruments following the standard operating procedure for this exact situation the captain handed Over Control to the first officer who then began flying the aircraft as the first officer continued the turn west the captain began troubleshooting the problem in an aircraft like the 747 the Adis received their information from a system of gyroscopes and accelerometers called Inus or inertial navigation units there are three Inu on board Inu 1 Inu 2 and as you'd expect Inu 3 normally the captain's ad receives data from inu1 the first officer's ADI receives data from Inu 2 and the standby ADI takes data from Inu 3 the captain could see that the standby ADI and the first officer's ADI were matching it was only his own which was giving a different reading so their Inus were likely working correctly while his own was probably faulty if he wanted to get his ADI working he would need to feed a data for one of the correctly working Inus so he switched his instrument to its Alternate Source using this switch here the compass stabilization switch this caused the data to come not from inu1 which was faulty but from Inu 3 within 5 Seconds of him flicking this switch the captain's ADI began working properly again and the warnings went away as the first officer rolled out onto a Westerly heading the captain took back control and continued climbing the aircraft after nearly two decades of flying and over 15,000 flights this aircraft wasn't exactly brand new problems like this although serious were hard hardly a shock to the crew What mattered on this departure was that they dealt with the situation in a calm and systematic manner this was their role in the system after all to use their training to quickly and safely fix the issues which were bound to emerge when operating a complex machine once the plane was in the cruise with the autopilot on the captain began testing out the system to see if the issue persisted he turned the switch back to the normal position for a while it appeared to be working but that was only because the plane wasn't making any turns as soon as the plane began making heading changes on Route the crew noticed that it was simply Frozen at Wings level interestingly it had no problem telling how much the nose was pointing up or down but in turns it was unreliable clearly it wasn't the ADI itself that was faulty but the system which was feeding it information the inertial navigation unit the captain turned the switch back to the alternate position and again his instrument began taking data from Inu 3 for the remaining 7 hours the fight progressed as normal across northern Europe with the switch in the alternate [Music] position at 5 minutes past 3 local time the 747 touched down at stanstead the pilots parked up at the gate and shut down the aircraft it would be too much to say that disaster had been averted there was no reason that a problem with one of the aircraft's three attitude Direction indicators should cause an accident but Aviation is a complex system every component part is linked to every other part if not by direct connection then only by a few degrees of separation we're about to see exactly how a fault with one of those components can propagate across the others and eventually stress the system to breaking point but first I want to say a quick word about this video's sponsor Opera Opera's new web browser is really a breath of fresh air in what has become a pretty stagnant browser space unlike a lot of today's browsers it's quick feature packed and easy to use one of my favorite features of oper browser is the tab Island feature I find this really useful because as I browse the web and open loads of tabs I can just organize them into Islands grouped by common themes so here I've got a tab Island for some of the stuff I'm studying as part of my flight training here I've got a tab Island for food I've been wanting to make and here I've got a tab Island for my work on green. Aviation I can expand and contract these tabs as I want which makes it so much easier to stay organized and productive it's also great to know that with the built-in ad blocker and VPN I can keep my data safe online with a single click I also find the sidebar here really useful it has WhatsApp Instagram and Facebook Messenger built in which makes it easier to stay connected to friends and family Opera even has its own browser AI ARA this is handy because whenever I have a question which Google can't answer I just ask ARA oper really feels like the future of the web everything I need is just there in the browser itself click my link in the video description to download Opera it's free it's fast and it just works now let's get back to the video Once the pilots had parked up at the gate the captain returned the compass stabilization switch from alt to Norm as part of his duties after shutting down the aircraft the flight engineer recorded the malfunction in the technical log book which included a reference code and the phrase Captain's ADI at display not reliable has gyro flag in view display okay when alternate attitude select Ed with that the flight crew packed up their briefcases and headed towards the door where the air stairs had now pulled up they will be resting in London for the day while another crew who had been staying at a hotel nearby would take the aircraft to its next destination of Milan on their way out the crew met a Korean Airlines ground engineer Kim iluk despite usually being based in Moscow Kim had to travel to stanstead because Korean Air didn't have permanent engineering support there similar situation existed in Milan this meant that Kim would be staying on board for this next flight his role at both stanstead and Milan will be to take charge and coordinate with local mechanics to swiftly fix any issues that had Arisen during the previous flight as the outgoing crew was leaving the aircraft the flight engineer told Kim about the issue with the captain's ADI He also mentioned that the problem was resolved when the captain switched the attitude and Compass stabilization switch to alt the flight crew then left for their hotel with no idea that the first steps had now been made towards disaster as the new crew for the flight to Milan made their way to the airport Kim and the local engineer at stanstead began preparing the 747 for its flight they did an extensive walk around of the aircraft ensuring that the plane was physically fit to fly and they also supervised the cargo loading and refueling once this was done they headed to the cockpit to sort out the issue written in the tech log this is where things started to go wrong for fight 8509 when Kim opened the tech log and read the entry from the fight engineer he couldn't tell what the code the fight engineer had written referred to to find out exactly what it meant he would need to get hold of an engineering manual known as the fim or fault isolation manual but since there was no permanent Korean maintenance outstation at stanstead there was no fim for the aircraft there Kim's personal copy was still in Moscow this simple lapse would turn out to be crucial that's because if Kim had managed to get a hold of the fault isolation manual he would have seen the procedure which instructed him to either replace inu1 or if that wasn't possible due to a shortage of spare parts to switch the captain's Compass stabilization switch to alt as the captain had done on the previous flight instead as Kim couldn't determine what the code meant he had nothing to go on but what the flight engineer had written Kim decided to remove the ADI and check for loose connections or corrosion while he got to work doing this the incoming crew made their way over to the aircraft and it was an experienced crew the captain for the incoming flight was Park duk C at 57 years old he had over 13,000 flying hours more than 8,000 of which run the Boeing 747 before joining Korean Air Captain Park had flon fighter jets for the South Korean Air Force it was not uncommon for Pilots at Korean Air to come from a military background and Captain Park's career was similar to that of many of his colleagues as a result of this military culture was deeply ingrained within Korean Air at all levels this culture would go on to play a vital role in the outcome of flight 8509 the first officer was 33-year-old Yun Kei sik Yun was a new hire with just 1,400 hours in total only 200 of which run the 747 this made him vastly less experience than Captain Park before starting on the 747 he had flown the 100 a much smaller smaller aircraft the jumbo jet was something of an adjustment and despite being fully qualified to fly it he was still very much learning the ropes accompaning the two pilots was 38-year-old fight engineer parun C like the captain he was highly experienced with over 8,000 total flying hours under his belt over half of which run the 747 as the pilot settled in the ground engineer had determined that a damaged connecting pin was the likely culprit of the captain's malfunctioning ADI he Enlisted the help of an engineer who was qualified to carry out the repair and together they fixed the pin and reinserted the ADI into the instrument panel once this was complete the first officer then carried out a test of the instrument sure enough when he pressed this test button here the instrument went through its full range of motion all the way up and down and to the left and right all appeared normal the test also checked whether the comparator warning was working to determine whether the computers would notice if there was a disparity between the captains and first officers instruments naturally the test showed that the comparator was working but oown to the crew or the engineers the test was a total waste of time there had never been any problem with the ADI nor with the comparator the problem was entirely with the Inu which fed the ADI its data it would turn fully left or right if the Inu only told it to but the IU was broken and incapable of doing that all the test did was to show that the ADI could rotate freely which it always could anyway but without full knowledge of what had originally gone wrong the crew were now lulled into a false sense of security as far as they knew their instrument had been fixed with that the pilots made the final preparations for departure Darkness was gathering and in a few moments the crew would be taking off from stanstead just before half 5 the crew had completed their checks and the plane had been loaded with cargo and fuel its takeoff weight would be over half a million pound 68,000 of which was fuel after a delay flight 8509 was finally issued its clearance to Milan the journey was scheduled to take 2 hours by now the crew had missed their original departure slot and the push back team originally assigned to their flight was attending to another aircraft with the clock ticking the pilots had to wait another 30 minutes before a push back crew became available at A4 6 the toe bar was connected and the massive aircraft began its push back away from the stand finally the plane was on its way but just as the crew thought their problems were over there was a call from the ground crew they could push the heavy 747 no further the push back tog lacked the power needed due to the 747 now being between the stand and the taxiway the crew were unable to taxi to the runway from the current position as a result they had to wait for a marshaler to guide the plane this caused a further delay it was almost as if fate itself was intervening trying to prevent the plane from departing but at 25 minutes past 6 fate let up flight 8509 was cleared to taxi to Runway 23 at stanstead as far as the crew were concerned the Clockwork was running slowly they had no idea that the problem lurking just beneath the surface was far more serious and it had nothing to do with the faulty instrument or the delays or the weather after all of the delays and the issues with the push back tog Captain Park was growing impatient in between the first officer's radio Transmissions to air traffic control the captain began to admonish him in one Outburst dissatisfied with the way Yun was handling Radio Calls Park said make sure you understand what Ground Control is saying before you speak in complete contravention of Korean airs standard operating procedures Park then began handling the radio work himself while taxing the aircraft he had now taken the first officer out of the loop taking on most of the work in the cockpit himself this crew was not a team as if that wasn't enough during the taxi when air traffic control called the plane and the first officer didn't respond the captain gave out to him for failing to answer Yun was damned if he did and damned if he didn't this highly unpleasant working environment caused directly by Park's attitude towards his inexperienced first officer was a symptom of the high power distance culture prevalent in South Korean Society in the year 1998 a group of pilots from New Zealand conducted a safety audit report on Korean Air which revealed significant issues with the airline the report brought to light a pervasive level of complacency arrogance and incompetence throughout all sections of the Airlines flight operations between 1970 and 1999 Korean Air had 16 aircraft incidents and accidents which which caused nearly 700 casualties the report suggested that the airlines organizational culture which is heavily influenced by South Korea's national culture played a significant role in these incidents as flight 8509 taxied out to the runway that evening the worst elements of this culture were on full display Captain Park continued to braid his less experienced first officer who became increasingly resigned and less willing to challenge the captain for his mistakes or for breaking Sops it wasn't that the captain was having a bad day the attitude he displayed was endemic within the airline but then another instrument started having problems as the flight continued his taxi to the runway Park noticed that his instrument which showed the plane's distance to radio beacons was displaying an incorrect value the display should have read close to zero because the beacon was at the airport however it was displaying a distance of 399 nautical miles this was another source of frustration for the captain he needed to use his distance from that Beacon to judge where he should take his first turn after takeoff if his distance measuring equipment wasn't working how would he know when to turn the captain was especially concerned about this because there was an active noise monitoring program in operation around stanard airport if he stayed outside of the designated departure routing his bosses back in Korea would receive a noise complaint which would not reflect well on him but there was a a simple solution to this problem according to the Pilot's charts they could use a different Beacon to guide their turn rather than relying on their distance measuring equipment to start the turn at a certain distance from the beacon they could begin the turn once they're at a certain direction from it all they would need to do was to tune their navigation radios to that Beacon and turn at the point described on the chart perhaps this is something that the first officer would have mentioned in a more positive working environment but given how things had gone so far what were the chances that the captain would be receptive to his mentioning this as the plane approached the runway the fight engineer provided the first bit of good news for the crew the instrument finally appeared to be working this would be the last bit of good news for flight 8509 at half 6 way behind schedule Air Traffic Control cleared the fight for takeoff the fight engineer pushed the throttles to the takeoff position and the 747 began its slow acceleration down the runway in a few moments the imperfections in the Clockwork would all come together there was no turning back now the captain lifted the aircraft into the sky and it disappeared into the low clouds over the airport the first officer made the standard call out as the plane passed 900 ft but seconds later the warning system that compares the two pilots Adis triggered this indicated that there was more than a 4dre difference between the captains and the first officers AI the problem which the plane had suffered from on the last leg was back but this time for some reason neither the pilots nor the flight engineer responded to the warning at this point the captain again said that his distance measuring equipment was not working he was fixated on this determined to make the turn at the correct point which was to be less than a minute after takeoff 1.5 mil from the beacon he confirmed with the first officer that the departure proed required them to turn onto a heading of 158° when they're 1 and 1/2 mil from the radio Beacon again the comparator warning sounded this time for 1 second but still the crew did not respond to this alert their attention was focused entirely on the point at which they needed to begin their turn short that this point had come the captain now began turning the aircraft to the left again the comparator warning was triggered this time after a few seconds the pilots canceled the warning but for some reason they didn't investigate further was the captain's ADI showing a different reading than the first officers given that they were in a turn low to the ground now would be a good time to check but the crew were distracted their focus was on the departure procedure and on trying to complete the turn successfully they didn't notice the growing discrepancy between the captain's ADI and the first officers as Park rolled the 747 to the left his ADI indicated that the plane was still flying with its wings leveled naturally he believed his instrument something all Pilots are trained to do it's not likely that he had ever encountered an ADI failure in his thousands of hours of flying as a result he continued holding his control column further and further to the left in order to get the stubborn plane to roll the first officer could see on his instrument that the plane was clearly already turning left and that this turn was increasing even though the captain couldn't see outside and hadn't yet thought to cross reference his own instrument against the backup one there was still a clue that something was off his ADI might have been providing false information but his flight director here was still working as the aircraft headed past the desired track of 158° the flight director began to demand a bank to the right and a pitch up Pilots were supposed to follow the fight director in this case the fact that it was giving Park instructions which were very different to the ones he expected which was a turn to the left should have clued him into the fact that something was a Miss but the captain ignored these cues the 747 Faithfully followed his control inputs and continued to increase its roll to the left his ADI simply indicated that the plane was Wings level on this flight it wasn't the captain who first noticed the problem but the flight engineer he had been closely monitoring the departure from his seat behind the two pilots and he had noticed that according to the captain's ADI the aircraft was not turning in line with his control input puts he told the captain the bank is not accepting the captain didn't respond when the aircraft rolled past 30° of Bank the flight engineer made the standard call out Bank bank this call was intended to bring the captain's attention to the standby attitude indicator so that he could see that his own ADI had failed Park failed to do so so hellbent was he on completing the departure procedure correctly that he' begun to tune out every everything else crucially at no point did the Young first officer with a fully functioning ADI challenge the captain's actions he didn't respond to the comparator warning or to the fight Engineers warnings it's possible that with just 195 hours on the 747 who's unaware of the significance of the comparative warnings but what's more likely is that after being repeatedly berated by the captain for his incompetence earlier on in the flight he did not wish to antagonize him further ironically it was the Captain's lack of faith itself in the first officer's competence which led to the first officer withdrawing and actually becoming a less effective pilot under normal circumstances the right thing for the first officer to do would be to immediately alert the captain to the aircraft's extreme Bank angle and if that didn't work he would have to take over control of himself the situation was now rapidly deteriorating the aircraft was low to the ground and its turn had gotten so sharp that it was beginning to descend Park was still holding his control column to the left long after he should have let go and still his ADI was indicating Wings level the plane was now banking past 45° then 50 then 60 as the bank angle approached 80° the 747s wings were no longer able to maintain lift and the plane began to descend rapidly even now with the aircraft screaming towards the ground Park was fixated on ensuring that he hadd complied with the requirement to commence a turn at 1 and 1/2 miles from the radio Beacon he asked the first officer to request a radar Vector from Air Traffic Control but you never got the chance to do this the plane was now fully on its side and its nose was pitching more than 30° below the Horizon the sound of the wind rushing by the cockpit as it plunged towards the ground was only interrupted by the fight engineer saying boy Bank Split Second later the plane hit the ground there were no survivors from takeoff to impact took just 56 seconds Korean Air's response to this incident was profound the airline completely modernized its crew Resource Management training program which was the first time it had significantly updated it in almost 15 years never again would a power imbalance in the cockpit lead to a crash but they didn't stop there as well as this Korean Air began training its Pilots more often on unusual attitude SC scenarios and on instrument failures if the captain of flight 8509 had recognized that his ADI had failed even relatively late into the turn he would have been able to recover the aircraft the airline also made changes to how it did its maintenance relying Less on contractors and expanding its engineering bases so that it had permanent staff at nearly all of its destinations hundreds of other smaller changes were put into place over the following months and years completely transforming the culture within the airline the year 2024 marks the 25th anniversary of the loss of flight 8509 it is thanks to these changes that in those 25 years not a single Korean Airlines plane has crashed causing fatalities this has been the trend in the industry more generally which is why Aviation continues to be by far the safest way to travel
