the Scandinavian Airlines md81 carrying 129 passengers and crew experiences serious engine problems just seconds after takeoff from stocko the pilots are confused about what is happening the vibrations from the engines are so severe that they cannot read their instruments then suddenly both engines fail flight 751 is now a 50ton glider will the pilots be able to haul their plane back to the airport or will they be faced with the Dreadful possibility of having to make an emergency landing in the densely forested Swedish Countryside the lives of everyone on board hangs on the split-second decisions the pilots will now make this is the story of SAS flight [Music] 751 it was the night of December 26th 1991 and the weather at Stockholm's Orlando Airport was typical of Nordic Winters biting cold and wet a Scandinavian Airlines McDonald Douglas md81 had just pulled up at the gate after an uneventful flight from Zurich the passengers and crew had safely disembarked and the engineers then secured the aircraft for the night with nothing happen in the aircraft for the next few hours until the first flight of the morning it would be natural to think that nothing could go wrong with the plane but the first steps towards disaster had already been taken on its flight in from Zurich the aircraft had spent 2 hours cruising at an altitude where the air temperature was a full 62° C below freezing that's- 80° F over this period the fuel had been chilled to well below 0° C the danger here was not that the fuel would freeze that wouldn't happen until it got to at least 47° below Z which wasn't very likely rather the risk came from the way that the fuel is stored in commercial aircraft to maximize the space for fuel large commercial aircraft don't really have fuel tanks per se in the way that a car does rather the fuel is literally stored in the internal space within the Wings this is called integral fuel storage as in the fuel tanks are literally integrated into the body of the wing itself the skin of the wing is the skin of the fuel tank what this meant was that on this night as the plane sat at the gate the super cooled fuel chilled the metal skin of the wing to well below the outside temperature of 0° C this would be no problem at all were it not for the fact the drizzle was now falling onto the aircraft as the night went on the drizzle continued to fall the chilled surface of the Wings froze the water droplets forming a sheet of clear ice on the wings surface as the night progressed the drizzle turned into rain and eventually into snow bright and early the next morning the Scandinavian crew reported for Duty there were six flight attendants and two pilots they would be taking the aircraft and 123 passengers to Warsaw in Poland and then on to Barcelona in Spain leading the crew was 44-year-old Captain Stefan rasmusen rasmusen was an experienced pilot with over 8,000 fight hours he had started his flight training with the Danish Air Force Flying f104 Star Fighters before joining SAS to fly commercially in 1979 despite this broad experience the captain was relatively new to the md81 with just short of 600 hours on it he was joined in the cockpit on this morning by 34-year-old W CED Mark who' operate as the first officer C Mark is very new to the md81 with just 76 hours on the aircraft and 3,000 hours of Total flying time the relative inexperience of this flight crew might appear to be something of a red flag but as we'll see shortly the real issue wasn't their lack of experience but the training they had received from SAS it was a busy flight and as the 123 passengers made their way to the aircraft the ground crew began to inspect the wings tailplane and the fuselage for snow and ice the effect of snow or ice on the upper surface of a wing can't be understated for a wing to be fully functional there must be a smooth flow of air over the upper surface even the smallest bit of snow or ice can disrupt this smooth flow making it impossible for the aircraft to fly a number of fatal crashes have occurred as a result of wing icing including one I've covered here on the channel on the md81 the fuel tanks were designed so that whatever fuel was available would pull at the lowest point within the tanks this was at the wings inboard section section close to the trailing Edge where the wings were attached to the fuselage the pooling of very cold fuel in this area was such a well-known issue that it had earned the name cold Corner special attention needed to be paid to the cold corner by ground Crews as they DEC the plane after Consulting the captain the deicing crew had begun to spray both the upper and lower surfaces of the Wings with deicing fluid the hot mixture of water and glycol blasted the visible snow off the wings and after a few minutes and after 850 liters of fluid the process was complete the engineer who oversaw the deicing then reported to the captain that the plane was now free of ice wanting to be extra careful the captain asked the engineer to confirm that the lower surface of the wing had also been fully deced and the engineer confirmed that it had been with that important business out of the way as far as everyone was concerned the plane was now ready to go the captain had no reason to suspect that the ground crew who were used to Stockholm's cold Winters had done anything but an excellent job on the aircraft unfortunately this assumption was wrong on the inboard section of the Wings upper surface at the cold Corners a thin layer of clear ice remained untouched it wasn't visible to ground Crews and even though the air temperature was now above freezing the super cooled fuel inside the wing tanks had meant that this ice wasn't going to go anywhere a few minutes after deicing had been completed flight 751 received its push back clearance and began pushing back from the gate the Clock Was now ticking before we continue I want to give a quick mention to this video's sponsor War Thunder War 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aircraft on the slippery taxiways the runway itself had been cleared of snow and all that remained were some puddles of standing water the captain wasted no time when he reached the runway turning onto it and pushing the engines to take off power as soon as he had lined up the auto throttle system engaged setting the correct power for takeoff and fight 751 began thundering down the runway unbeknownst to anyone on board this was about to become the shortest flight in the airlines history within a few seconds the aircraft had reached its takeoff speed Captain rasmusen eased back in his control Colum and lifted the plane's nose into the air as the wings began to take the aircraft's weight they bent upwards compressing the skin on the upper surface but when this happened the ice which was stuck to the wings detached it then flew backwards straight into the engines when the ice hit the engine blades they were bent and warped out of shape the air flow through the engine was no longer smooth which would cause serious problems in a few short seconds up in the cockpit the pilots were as yet unaware of the damage they heard a low humming noise as the now damaged fan blades spun inside the engine but apart from that things appeared normal the captain continued climbing the aircraft into the low hanging clouds and the first officer raised the landing gear but just 25 seconds after takeoff the first real sign of trouble came loud bangs began to shake the aircraft with each bang it felt as if the aircraft was breaking heavily jerking the terrified passengers for in their seats the pilots could tell that something was wrong with the aircraft's engines the question was what they searched the engine instruments for any indication of what might be happening but the vibrations were so severe that they had trouble reading the displays after a few seconds of trying to analyze the instruments the first officer correctly deduced that one of the engines was suffering from compressor stalls the air flow through the right hand engine had been disturbed by the now misshapen fan blades to the extent that it was now backfiring and causing intermittent losses of thrust if the pilots didn't do something fast these stalls would tear the insides of the engine to pieces and that is where a strange circumstance of this flight comes into play Pilots are usually trained to deal with a compressor stall and the associated engine surges during their six-monthly simulator checks the correct response to a compressor stall is to reduce the thrust on that engine manually until the compressor stall stops if there is no further indication of damage the the engine thrust can then be gradually increased so that as much power as possible can be gained from it however bizarrely SAS did not offer training on engine surges despite them not being altogether uncommon now climbing out over Stockholm the captain was at a loss as to what to do SAS had also not provided any memory drills for engine surges despite how time sensitive a problem they were this meant that as flight 751 climbed with its right engine surging the crew would first have to identif ify the problem then find the manual that contained the procedure for dealing with an engine Surge and then find the relevant page for the checklist and carry out the appropriate steps the pilots simply didn't have time for this the engine would have long since destroyed itself before any such checklist could be carried out so with little training to go on the captain did what seemed reasonable to him he brought the power back on the right hand engine this was a step in the right direction but it didn't go far enough rather than bringing it back enough to stop the surges which was the correct procedure he just reduced Power by about 10% this had basically no effect and the engine continued to Surge violently this was compounded by a problem which man will know from the 737 Max accidents in more recent years namely one in which the pilots were not made aware of a system which could put them in danger in this case it wasn't mcass which the pilots were unaware of but a system called at or or automatic thrust restoration ATR was a feature of the plan's Auto throttle system which when it detected a difference in the thrust output between the two engines would increase power on both engines to overcome the loss in thrust just as with mcass on the 737 Max under the conditions it was designed for this was an extremely useful system but in the case of an engine surge an increase in engine power was exactly the opposite of what was needed increasing the power on a surging engine only damages it further and crucially the pilot didn't know about ATR SAS had never told them of its existence so after the captain had pulled the right engine throttle lever back in an effort to reduce the vibrations the ATR quietly pushed the lever back up it would have been a good idea for the pilots to disengage the auto throttle at this point in order to have full control over the engines but In the Heat of the Moment the captain didn't do this neither pilot noticed as the right hand thrust lever slowly crept forwards almost to its previous High thrust position the damage to the right engine was getting worse and worse before long it wouldn't be producing any thrust at all at this point Air Traffic Control were unaware of the aircraft's plight they continued to issue clearances to other planes in the area and were preparing to issue further climb instructions to fight 751 only the passengers and crew on board knew that anything was wrong with the aircraft but even at that they had no idea of the full extent of the danger they were in that's because it wasn't just the right engine which had suffered damage from the impact of the ice 40 seconds after the right engine had first started surging the left engine also began to Surge the ice had so damaged the blades that they were now unable to keep the air running smoothly through the engine and it was beginning to sputter and backfire but still confused about what was happening their aircraft the pilots thought that these noises were simply more stalls coming from the right hand engine they never even considered that the left engine might be in trouble too after all what were the chances that two engines would simultaneously start to experience compressor stalls pretty high as it turns out if they've both just inhaled large quantities of ice but again the pilots had been told before departure that there was no ice on their aircraft as the plane climbed through 2600 ft the captain pressed the autopilot button so that he could be freed up to deal with the aircraft's problems but the autopilot couldn't deal with the aircraft the state that it was in it disengaged as soon as the captain pressed the button there was no way around it the pilots were going to have their hands full for the rest of this fight passengers sitting in the front of the cabin near the cockpit could hear the autopilot disconnect warning repeatedly sounding which the pilots were too busy to silence one of those passengers was an off-duty SAS Captain per halberg halberg could tell that an engine was surging and from his seat near the front he could see the pilots trying to deal with the problem near the back of the aircraft was another off-duty SAS pilot this pilot told one of the flight ATT tenants to inform the pilots that an engine was surging the flight attendant called the flight crew on the intercom but they were too busy to answer at this point with the right engine tearing itself apart the pilots needed to significantly reduce the thrust on the engine but the captain was reluctant to do this fresh in his mind was the training he had received about the kegworth accident in the UK which had occurred just 2 years previously in that accident the pilots had experienced serious engine problems and had inadvertently shut down the wrong engine this led to the aircraft crashing into an embankment just short of the runway killing 47 people as a result of that accident Captain Ras musen had been trained not to act in haste he figured it would be far better to take his time diagnosing the issue than to make a quick but false diagnosis which could Doom the aircraft and its passengers so he kept the right hand engine at its high thrust setting and it continued to disintegrate but the crucial thing which neither pilot knew was that the surging was not confined to just one engine both engines were now surging inside their casings metal blades at hundreds of Dees C were grinding together being heated by hot gases and scraping against their casings tearing the engines apart just seconds after the left engine had started to Surge the right engine failed 2 seconds after that the left engine failed as well 3,000 ft above the ground and still in the clouds flight 751 was now nothing more than a 55ton glider with nothing to propel them forwards the passengers and crew felt a sickening sinking feeling as the plane suddenly decelerated its shallow climb peaked at an altitude of 3,300 ft before turning into an inevitable and final descent up front the pilots were in disbelief in a matter of seconds they had gone from having an engine problem to being in a life and death situation without engine power it was only a matter of time before the plane hit the ground and at an altitude of 3,000 ft the pilots would have no more than 2 minutes until impact every second every Split Second decision would now make the difference between life and death for the pilots and for the 129 passengers and crew the captain ordered the first officer to restart the engines but as soon as the first officer tried to restart the left engine it bursts into flames looking at the engine instruments he could see that the outlet temperatures for both engines were over 800° C he pulled the fire extinguishing handle on the left engine putting out the blaze their only hope now lay in the right hand engine completely unaware of the aircraft's problems Air Traffic Control cleared the fight to climb to 18,000 ft the first officer radioed back telling them that they were having issues with their engines and needed to return to the airport in the front of the cabin off-duty SAS Captain per halberg was all too aware of what had just happened he could see warning lights Illuminating on the overhead Annunciation panel but curiously the pilots appeared not to be communicating nor do they have their hands on the throttles halberg was so concerned by this lack of action that he considered that the captain might have had a heart attack he jumped out of his seat and offered his assistance the captain told him to start the Apu or auxiliary power unit which would provide backup electrical power the first officer then handed him the emergency checklist so that he could help him try to restart the remaining engine this sharing of the workload was vitally important the only task the captain had was to steer the plane back towards the airport the other two pilots could then do everything in their power to work through the aircraft's problems the first officer turned the right hand engine starter switch to continuous ignition and an attempt to relight it but it was no good the engine was damaged Beyond repair and with the fire extinguisher having been discharged into the left engine there would be no restarting that either it was beginning to look like their glider status was permanent the captain had entered a shallow left turn hoping that somehow his crew would be able to restart the engines in time for him to make the airport if they couldn't he would have no choice but to put the plane down in a field something he wanted to avoid at all costs but with the aircraft still in the clouds there was no way for him to fight find a landing spot all he could do was to descend gradually maintain his speed and hope that when he popped out of the clouds there was a field there waiting for him and as hard as that already was he now faced a new challenge without electrical power his two main displays had gone blank without them he was now relying solely on the tiny standby instruments to tell him his altitude speed and whether he was pointing the nose of the plane up or down this was a nightmare emergency and the captain was utterly overwhelmed the off-duty pilot could see this rasmusen was frantically directing his attention around the cockpit not at the key information of speed and altitude but at other less critical instruments halberg was afraid that in his distracted State the captain would inadvertently stall the aircraft making it fall from the sky repeatedly he urged the captain to look straight ahead he could see from the first officer's instruments which were working that the aircraft was getting dangerously slow he needed to put some buffer between their current speed and their stall speed so he deployed the slats at the Leading Edge of the wing this provided some extra lift without creating too much drag turning back to look through the open cockpit door Captain rasmusen shouted to the cabin crew prepare for an emergency again halberg reminded him to look straight ahead he would need to focus solely on flying the aircraft within 30 seconds hmar had fully extended the flaps the aircraft was now descending through one 1,100 ft and time was running out again the captain shouted back into the cabin telling the cabin crew to prepare for an onr ground emergency homber repeated this order back to the cabin and the flight attendants began telling the passengers to brace all three Pilots understood that at their low altitude there was no chance of returning to the airport they had just seconds to find a landing spot which was free of obstructions not an easy task in the densely forested area around Stockholm finally flight 751 burst out of the clouds the crew's options now became Crystal Clear their only option was a small field dead ahead the captain aimed for it steering slightly to the right to avoid houses the cabin crew shouted at the passengers to brace for impact the pilots now had just seconds to make any last minute adjustments one decision they had to make was whether to lower the landing gear now or to wait until they were closer to the ground if they did it now they would increase the drag on the aircraft potentially making it impossible for the aircraft to Glide Beyond the Forest but if they waited too long to extend the landing gear it might not have locked into place by the time the plane hit the ground for the moment the pilots decided to hold off halberg had set the flaps to their lowest setting 40° this created a lot of lift but it also produced drag which reduced the plane's gliding distance at a time when it would need to clear the trees at the same time to minimize the impact forces a slow aircraft was Far preferable the crew knew that these small decisions would each contribute to the outcome whatever it ended up being Captain rasmusen delicately moved the controls trying to get as much distance as possible out of the Glide sitting behind him halberg urged him to stay to the right and aim for the farest rather than for the houses closer to them it was eerily silent on board as the aircraft swooped over the snow covered Treetops below as the plane got lower the grand proximity warning system alerted the pilots that their landing gear was still kned down the first officer suggested that they finally lower the landing gear the chances that they'd be useful for allowing the aircraft to roll to a stop were pretty low they would likely be destroyed on impact but they would at least absorb some of the shock of the impact saving the fuselage and therefore the passenger cabin from the worst of the damage halberg agreed that now is the right time and first officer Cedar Mark lowered the gear the grandp warning system alerted the pilots to the impending collision with the ground with just seconds to go the first officer radioed Air Traffic contr Control saying and Stockholm Scandinavian 751 were crashing into the ground now halberg knew that he wouldn't survive the impact if he stayed standing in the cockpit but at this point he didn't have time to strap himself into his seat in the passenger cabin either so he ran back out the cockpit door and braced himself against the forward cabin wall the plane sunk into the dense Pine fire ripping off its right hand wing it then slammed into the rock hard frozen ground the fuselage snapped into three pieces and it slid across the snow covered field for over 100 m finally there was total silence the plane had ground to a halt though eight people were seriously injured incredibly everyone on board survived the crash many of the passengers even escaped the plane completely unharmed Sweden's Board of accident investigation got to work immediately after the accident to determine why things had gone so badly wrong on flight 751 and also to make sure that such incident would never occur again they determined that the main cause of the accident was inadequate procedures at SAS for ensuring that no clear ice was on the wings before takeoff they also concluded that the Pilot's lack of training on identifying and eliminating engine surges contributed to the accident as to their lack of knowledge about the automatic thrust restoration system if the pilots had known about how to deal with the compressor stall and had applied these procedures correctly the engines would likely not have failed and they would have been able to return safely to the airport as a result of this investigation the board recommended that those tasks with deising an aircraft should be given full instructions and provided with procedures to ensure that aircraft would not take off with clear ice on any part of the upper wing it also highlighted that there should be a way for the pilots to turn off the ATR which caught the pilots of flight 751 completely off guard and contributed to the loss of both engines the bizarre situation that SAS Pilots had not been trained on what to do in the event of an engine surge was also addressed the investigation team determined that the engine surge procedure should become a memory item and should be practiced regularly in the simulator ice remains a serious threat to commercial aircraft but these safety improvements have meant that there hasn't been an incident similar to this one in the over three decades since it took place thanks again to warthunder for sponsoring this video play warthunder now for free on PC Playstation or Xbox by using my link in the pinned comment below or in the video description new players or those who haven't played in over 6 months will get access to a massive Bonus Pack available across all platforms this pack includes lots of Premium vehicles and an exclusive vehicle decorator it's available for a limited time only so be quick
