Deadly Obsession | Investigation of Thai Airways 261

this Airbus A310 was on its third attempt to land at Surat to Tani airport in Thailand on the previous two attempts the crew had been unable to find the runway this was their last chance otherwise they would have to return to Bangkok the crew becomes so focused on Landing that they failed to see that the aircraft has now entered a stall what the crew do next only makes the situation much worse to see what happened and why stay tuned on the 11th of December 1998 this Airbus A310 belonged to Thai Airways International was on a scheduled passenger flight to Surat Tani Airport the flight had originated in Bangkok International Airport and on the aircraft there were two flight crew 12 cabin crew and 132 passengers on board for the flight crew the Pilot's total flying hours were 10 167 with 3088 on type for the co-pilot his total flying hours were 2839 with 983 on type but 1605 on a similar type aircraft before departing Bangkok International Airport the crew received weather forecasts for their trip the weather forecast for between one in the afternoon and 10 at night was variable wind a velocity of eight knots with a visibility of 7 000 meters rain showers with low Cloud at 1 800 feet and overcast at 11 000 feet they also received a further forecast for temporary weather during that same time period and it was variable service wind with a velocity of 15 knots gusts into 25 knots with the visibility of 1 500 meters rain showers low Cloud at 1 200 feet broken Cloud at two thousand feet and overcast at 11 000 feet it's worth noting at this point that Thai Airways policy for landing at Surat Tani airport the visibility couldn't be less than 2 200 meters the crew opted to continue with the trip even with the forecast temporary weather as for the majority of the time the visibility was looking to be greater than that at 7000 meters as well as the weather information the crew also received several no Tams now no Tam stands for notice to Airmen and these are notices there's four aircraft Pilots of potential hazards along their flight routes or at their location that could affect the flight so in this situation the crew were informed that the instrument Landing system or ILS at Surat Tanya airport was unserviceable along with that the Precision approach path indicator or Pappy's you might have heard them is a lighting system either side of the runway to inform the pilots they're on the correct Glide path one of them on the right hand side of the runway was unserviceable at this time and also the non-directional radio Beacon or NDB was also unserviceable during this time so the crew were aware that the ILS the NDB and one set of papillites were unserviceable for their approach they did still however have the VOR DME and it was this navigational Aid that they decided to use so a VOR DME are actually two separate systems the VOR which is actually an acronym within an acronym stands for a very high frequency VHF omnidirectional range so VOR overall now the way this system works is it's a radio Beacon so it will fire out two separate signals and the aircraft will have an antenna that receives those two signals and can interpret a radial based on that radio Beacon this means that if you have a VOR nearby and you are tuned into their frequency your aircraft will have a pointer that can tell you exactly where that Beacon is and then you can use that radial to fly along a track towards or away from that Beacon and the other part DME it stands for distance measuring equipment and this will give you the distance the aircraft is from the beacon so using the VOR and the DME together it will give you a position and distance telling you exactly where the aircraft is in relation to the beacon one thing the VOR DME can't do is provide any vertical guidance this means that if you're using this for an approach it will have to be a non-precision approach which means your minimum height that you can descend to will usually be a bit higher than if you are using a Precision approach such as an ILS the way pilot gets around this is there will be vertical guidance on the approach plates that will relate to certain points in space relating to the VOR DME we'll run through those plates later on in this video as they play a major part in this incident so the time was now 1826 and the crew were 70 nautical miles away from Surat to the airport the co-pilots then got in touch with the approach controller and they gave them instructions to execute the instrument approach procedures expecting the VOR DME for Runway 2-2 they then gave them an update on the weather and the surface wind was calm with the visibility of 1 500 meters light rain and a cloud base of 1 800 feet the minimum visibility was below the company required standard of 2 200 meters but with the aerodrome still 70 nautical miles away the crew may be believed that the weather will pass through and the visibility could improve by the time they reached the Airfield so the crew now decided to brief the approach they were going to fly and they used the approach plates they had within the cockpit now these approach plates were provided by the flight route facility Department of Thai Airways the problem in this instance is that these plates were created after an instrument approach procedure meeting on the 12th of February 1998. however they differed from the up-to-date plates on the aeronautical information publication of Thailand now the difference is on their own weren't too catastrophic they had slightly different tracks and slightly different holds about 10 degrees different from each other the difference was compounded due to the visibility issues but also it changed the crew's perception of where they were in the airspace on the official approach plate they had them on a track of 204 degrees but also informed them that the inbound track was offset 16 degrees from the runway Center Line this means that they expected the runway to appear on their right hand side as they were visual of the runway whereas the track they were using on their plate was 215 and with the runway on a 225 the runway Center Line will be offset much less and it should be expected on the nose or just slightly right of the nose the reason why this was happening was because the VOR Beacon was located on the left hand side of the runway not at the threshold or before it therefore they were flying toward the beacon which was already left of the runway so you'd expect to see on the right hand side as you were visual on a day where the weather was good they would see the runway Center Line much sooner than when the weather was poor as what they were flying today the crew then set the aircraft up for their approach and informed the aerodrome controller that they were over the intermediate fix the controller that informed him that the Papi lights on the right hand side of Runway 2 2 on serviceable and that there was an obstacle 400 meters from Runway 2 to threshold the crew continued on their approach and then reported pass in the Final Approach fix the aerodrome controller informed the pilot that the aircraft was not yet in sight however they were clear to land on Runway 2-2 shortly after the co-pilot reported that the airport was in sight they then disconnected the autopilot but realized very quickly that they were not going to be able to turn the aircraft towards a runway in time they decided to go around they slowly increased the thrust from 70 N1 to 102 N1 and during the go-around they noticed that there was a high rate of climb the co-pilot there mentioned it might have been because they were very light and they amended it and continued with their go-around after the go-around had been made the controller in the tower asked what distance the pilot saw the runway the pilots had informed him that there was about three nautical miles from the runway they also informed the controller that they were left of course which is the reason why they could not land on the first time whilst they were setting themselves up for the next approach they then ask the controller if it was raining at the Airfield to which he confirmed there was light rain at the Airfield the crew at this point had a discussion and agreed that it might have been because of the wind and rain as why they were pushed slightly left of track and how they found themselves in that position the crew then informed the controller they were at their Final Approach fix and again received clearance to land both air traffic control and the pilots were not visual with each other the pilots were again struggling to find the runway for the second time they finally saw it as it appeared out the right hand side of the aircraft they determined that they were unable to land and they decided to go around again this time with the autopilot and auto throttle engaged during the go-around the crew discussed that the approach was not in line with the runway because the aircraft was not in line with the VOR course the co-pilots also mentioned that he couldn't determine whether a light was one from a boat or from the runway so they were still unsure where the runway really was in comparison to where their approach track was taking them the crew then decided that they were going to attempt a third approach they did discuss that if this was not possible or they failed to land this approach that they would have to return to Bangkok the co-pilot then worked out the minimum fuels and they still had enough fuel to make an approach and if not return to Bangkok the crew then made an announcement to the passengers they said ladies and gentlemen we're unable to land we have to try again but if another Landing cannot accomplish we proceed to Bangkok thank you they then informed the controller that they intended to carry out a third approach the controller informed them that the visibility observed was approximately one thousand meters the frustration and pressure was now starting to build in the cockpit two failed attempts to land and a third one being the last before returning to Bangkok the crew were aware that this would have further impacts on the company one of the pilots said we fly back if not in time the aircraft won't make it to Chiang Mai the pressure was really building on this crew to get the aircraft on the ground when they were informed about the 1000 meters visibility the pilots were heard discussing one thousand meters unable but the decision was not made at that time to cool off the approach and they decided to continue still slightly confused on how they got into the position on each of these approaches they've been discussed and confirmed that the runway was on a heading of two to five the co-pilot said the Romer heading was actually two to five but the VOR track was 215. they continued on their approach and then reported to air traffic control that they were at their Final Approach fix the air traffic controller then said clear to land Runway 2-2 and then they discussed that they were clear to land we'll try again they continue to descend until they reach their minimum descent altitude the captain then said can you see and both the crew were looking at the windows trying to find the runway the autopilot was then disconnected and they continued to search for the Airfield leaving their decision as long as they could the pilot they emphasize cannot land cannot land and decided to go around again using the auto throttle the co-pilot then said trigger go levers and the engine power increased from 51 N1 to 102 N1 in eight seconds this again caused the nose to pitch up but because of the speed in which the throttles were brought to 102 percent that nose pitch up was a little bit more than the crew was expecting from the previous two go-arounds both the crew members were continuing to look out for the runway and whilst they were looking the pitch of the aircraft was continuing to increase the pitch attitude had now reached 18 degrees when the pilot put a small amount of pressure on the elevator to stop that rate of climb the crew then we're continuing to look for the runway and get to distracted and frustrated by the situation and the pitch then continued to increase it reached approximately 40 degrees before again the pilot applied the elevator and reduced the angle to about 33 degrees still looking for the runway that's nose attitude increased again to 48 degrees it was at this point the pilot said too close cannot land and when they check their instruments it was a nose up attitude of 48 degrees and an airspeed of less than 100 knots the aircraft was now in an upset position and very soon entered a storm the captain then called for climb power and tried to wrestle with the aircraft to get it to pitch down the request for more power was only increasing the pitch-up motion on the aircraft the captain then called for full power but this again made the issues worse as it caused the nose to pitch up more deepening the stool and making it even more unlikely that they were going to recover the crew continued to try and control the aircraft until at 1908 and 700 meters south of the airport the aircraft crashed into the ground of the 146 crew and passengers on board 101 were killed 35 were seriously injured and 10 suffered minor injuries in the subsequent investigation that followed this incident it was determined that the probable cause for this incident was down to a few different factors the first one being the pilot attempting to approach the airport in lower than minimum visibility the pilot suffered from an accumulation of stress and were not aware of the situation until the aircraft had entered the upset condition it was also determined that the pilots had not received adequate recovery training for wide-body aircraft Airbus had actually sent a document to Thai Airways on the 1st of February 1998. this document highlighted the fact that wide-bodied aircraft with edgin's under swept back Wings would lead to quite a strong nose up pitching moment when thrust was put through the engines this was exaggerated when the aircraft was lighter weight Thai Airways itself also published an article entitled aerodynamic principles of a large airplane upset and this was published in November 1998 the month before this incident the reason this is so important is because this training covered the store recovery for a high nose stall and the main difference for aircraft that had underwing mounted engines was that you reduce thrust when you enter that store so as we saw with this incident where the captain is asking for more thrust all that's happening is it's causing the nose to pitch up more thus increasing the stall if the crew had received the adequate training then obviously they would have reduced the thrust and potentially that would have caused the nose to dip enough to recover from the store it also couldn't be determined if the store warning and Pitch trim systems had functioned correctly due to the high angle of attack that the aircraft had experienced the pitch trim system should have activated to assist in bringing the nose down this may have added to the issue as it might not have been functioning correctly it was also determined that the approach charts that the pilots were using that were issued by Thai Airways were for a trial and due to the nature of that approach chart they would actually need a minimum visibility of 4 800 meters to be able to see the runway Center Line when it was intercepted on that VOR track now the safety recommendations that came out of this incident were that Pilots should strictly follow all procedures set forth in the flight operation manuals any flight safety documents that the operator has already assured for its safety should be certified by the authority and that Pilots should undergo airplane upset recovery training that last one's a bit of an understatement if you're interested in watching any more air crash investigations check out this playlist here thank you for watching this far and I'll see you in the next one

Channel: Curious Pilot

Views: 57,899

Keywords: Air crash investigation, thai airways 261, thai airways international 261, thai flight 261, airbus a310 crash, a310 crash, airplane crash thailand, #air crash investigation, where to watch plane crashes, where to watch air crash investigation, mayday air disaster

Id: s3gruAWGr6A

Length: 16min 42sec (1002 seconds)

Published: Sun Mar 19 2023