New Details Vilnius DHL 737 Crash 1 Dec 24

[@consortiumxf]

Probably one of the best exclusives you've done.....WOW. Great update!

[@stay_at_home_astronaut]

I had a slat actuator fail structurally on a B-727, back in the 1980's. The slat on that wing would not retract as the broken actuator stopped them from moving due to exhausting the hydraulic fluid. The actuator must have broken after the slats were extended for landing as the slat was stuck in the fully extended position, as advertised. A trail of skydrol went from the high-speed taxiway all the way to the gate at Miami International, as the pumps spewed out the majority of the system's fluid. The actuator failed when the threaded end cap, that the strut comes out of the cylinder from, had a pie-shaped piece depart from the rest of the cap. About 1/3rd of the cap followed with the actuator rod/strut, with the rest of the cap still screwed into the cylinder. What was amazing to me was that the teflon seals never actually broke, but were stretched along the axis of movement of the actuator, but were still in one piece.

[@chrishauser5505]

Jesus. Glad you walked away from that one.

[@brentbeacham9691]

Could the skydrol upon impact squirted out of the pump? So the configuration of the leading edge looks retracted.

[@vaulthecreator]

​@@brentbeacham9691I just had that very question pop into my noggin and came here to ask but you put better than I would have.

[@vaulthecreator]

​@@chrishauser5505Indeed 😳

[@jdshemp]

@@brentbeacham9691 No they usually remain in the pre crash position, accident investigators depend on measurments of the chrome portion to establish the position of the flaps, or other similar systems.

[@jamsaanich4993]

Your analysis is impressive. You never speculate without providing relevant details and facts that may indicate contributions to the specific outcomes. The presentation is easy to follow, intelligent, logical, and thoroughly explained. Thank you.

[@MrBsbotto]

I'll say! A top-notch, professional explanation of the problem! Even a non-industry dinosaur like me was able to follow the tech stuff fairly easily. Thanks for taking the time to educate us.

[@fabrizio7181]

Ok ma gli avvisi in cabina di una configurazione all atterraggio non corretta hanno suonato? Non li hanno sentiti?

[@dukemetzger3784]

And this is why I love this channel! I don't generally comment here, but damn I do like getting accurate information! Thank you !

[@erikwigelandiestad2270]

❤

[@imagine9033]

It’s only that accurate as the information he gets. If the Information was a fake….

[@thomaswerner8821]

Fully agree with you👍👍

[@jordanbicknell1228]

I’ve experienced two flap issues on the 737. One occurred after takeoff, where the flaps wouldn’t fully retract. The other happened during approach, with the flaps failing to reach Flaps 1. On the NG and Max, you’ll get an “Airspeed Low” aural alert if your speed is too slow for the actual flap position. In the Classic, if you’re distracted, the first indication might be the stick shaker.

[@tedstriker754]

I still am amazed anyone survived that accident, considering the fireball it made when it went down.

[@ghostrider-be9ek]

the flight deck broke off apparenrlyt and rolled away from the fireball

[@tedstriker754]

@@ghostrider-be9ek What a stroke of luck!

[@rranger1014]

It's an entirely different kind of flying, altogether.

[@timburke127]

@@rranger1014 IT'S AN ENTIRELY DIFFERENT KIND OF FLYING

[@chrisnoname2725]

@@rranger1014what is?

[@eddiehimself]

To those asking: the flaps and slats will remain in their current position if hydraulic pressure is lost; they won't retract.

[@mediocremike5986]

Could the slats ram be pushed back in by a violent impact?

[@Wannes_]

Could they be pushed in on impact ? Or would they rather bend as they hang a fair bit below the wing ?

[@jochenheiden]

Sorry, I do not agree at all with this assessment. The slats are locked into their position with a liquid lock. If there is no longer continuity in the hydraulic system that liquid lock is lost and the actuator could be easily pushed back in by a strong force.

[@jochenheiden]

@@mediocremike5986100%

[@wjatube]

@@eddiehimself there was no indication they lost hydraulics. They would've known long before configuring to land. It would've been a high risk landing requiring equipment.

[@reefkeep2]

Most usually when the slat actuator is out is mechanically locked out, so it can’t move on its own back. It’s hydraulically unlocked and yes, that is a slat actuator

[@paynej32013]

That would've been my question. If that's the case an impact wouldn't retract them but rather bend the actuators.

[@NickyNiclas]

@@paynej32013 It depends on the forces involved in the impact but if it hit the ground hard enough, the pressure generated would probably rupture the hydraulic lines and push it in.

[@user-rl3ef4ju9k]

@@NickyNiclas sudden impact can not push the fluid out of the cylinder without a big hole somewhere. The rod will bend more or less.

[@RoBert-ix6ev]

It is hydraulically locked. The slats themselves have the intermediate and full extens detents, mechanical.

[@LegioXXVV]

There is no mechanical lock on a 737 slat actuator as such. There is a hydraulic lock to prevent blow-back on the slat mechanical assembly, but that's not the same thing. Either way, the lock is not on the actuator itself, so it possible to retract the actuator rod if it becomes detached from the slat. The hydraulic lock can and has failed on some aircraft in the past, and the lock has been released by failure of the standby system, even when the hydraulic pressure was above 2000 psi. It may well turn out to be the case that the slats weren't extended, but I'm afraid it'll take a little more proof than that photograph.

[@MarcDasent-wh9ej]

Excellent analysis. Excellent video. 737 driver 21000hrs. Retired.

[@malalexander3515]

Juan, thanks for this informative update. Love it when you announce you are in Sydney, my home city.

[@oldcynic6964]

Where was he ? I can just see the top of the Opera House, so I'm guessing Milson's Point.

[@SoundzAlive1]

Looks more like George St or Pitt St, Circular Quay/ André in Sydney

[@jimpalmer1969]

This aircraft EC-MFE was delivered new to Australian Airlines Oct 6, 1993. 737-476(SF) S/N 24445, operated by Swift Air Reg No EC-MFE. On 3-19-2015 the conversion to 737-476SF was completed and delivered to Swift Air. The 737-400SF is an 8/9 pallet cargo conversion by AEI performed at Dothan, Alabama.

[@NicolaW72]

Indeed. It was an aged aircraft and a converted freighter.

[@AndyG_64]

The old VH-TJT would therefore have my DNA on it still ... 😞

[@NicolaW72]

@@AndyG_64 It´s a really sad end being smashed in pieces in a courtyard.

[@Ticklestein]

THANK YOU FOR PRONOUNCING VILNIUS CORRECTLY ❤️🙏🏼

[@davidtx8777]

It’s pronounced like it’s spelled.

[@carlyellison8498]

Thank you for spelling it's correctly - twice.

[@frankgulla2335]

Great update, Juan. Thank you.

[@craigbmm4675]

ya , good video

[@frank_av8tor]

If leading edge devices were not fully extended, they should have gotten a GPWS "TOO LOW FLAPS" Warning if they had forgotten to lower their Flaps to 30° or 40°. They were clearly inside the warning envelope. This warning is a mandatory Go-Around as it means the aircraft is not stabilized. Thanks for the update!

[@gordonbryan8381]

For those that do not know, each slat section has its own (at least 1) actuator. It is not just one big actuator that extends all the slats on each side of the wing. At the speed this aircraft was flying, 1 slat not extending fully would have made no difference on how the airplane was flying. It certainly would have not caused any type of quick nose down pitch. They were unstable (using US FAA standards) all the way down from glideslope intercept. As in most unstable approaches, a simple go around and another trip around the pattern to get their (you know what) together is all it would have taken. A go around is the ultimate safety maneuver: it removes you from an extreme situation, and you go back and return in a safe situation and land safely.

[@gmcjetpilot]

You know they are linked with Slat Asymmetry warnings, if you had any one or more slats retracted and other extended on one side or from side to side you get warnings galore. It is not numeral for slat or flap asymmetry or to have slat skew or stuck sections without warnings through position limit switches.

[@AnneOseraccount]

why so defensive? don't wanna spell 'Boeing equipment malfunction'?

[@mikewatson4644]

@@AnneOseraccount This aircraft had been flying for 31 years. Would you be blaming the manufacturer of your 31 year old car for having a breakdown? Maintance, or lack thereof, is a more likely cause for a failure of a part. There is some possiblitiy of operator error being involved also. Let's wait for the report

[@slpater1]

@@AnneOseraccount oh wise one do tell what information you've obtained that would point you towards equipment failure being the main cause of this accident.

[@hbtried7818]

@@AnneOseraccount 🙄

[@TheLincolnshireFlyer]

Brilliantly explained for us. Thank you for the video 👍😊

[@SomeOne-mp6ym]

Thank you Juan. I'm so glad you are following up on this incident.

[@danielislive]

Thank you Juan for yet another informative clip. As a 737 pilot myself, I´m looking forward for more info on this terrible accident. Very interesting finding this slat actuator. Did the viewer that send you the picture comented about the configuration of the remaining slat actuators?. That would be very useful information, but anyways, we´ll have to wait for the preliminary report, Let´s just hope Lithuanian authorities release the preliminary soon.

[@vintagesupermarkets5210]

I will be very curious about crew fatigue and circadian rhythms given the time of day of the crash and whether that will be a factor in the unstable approach situation.

[@Raptorman0909]

The roll right just before the crash was almost certainly a consequence of a stall and, if the flaps settings were as it appears, they would have had a good deal less lift for the speed they were going.

[@paulroling1781]

Likely due to a last moment high g pull up.

[@chrisg9627]

I don't agree, perhaps the initial report will clarify this.

[@Raptorman0909]

@@paulroling1781 Maybe, but if they were approaching without the proper flaps setting the lift would be much less so an approach at the normal speed would result in marginal or insufficient lift. If the lift is less than the weight the plane is going down EVERY ... SINGLE ... TIME! I did not see a huge pitch up just before the crash, they were coming in and descending at what appears to be a relatively normal slope when the plane began to roll right which to me is an indication of stall. Pilots are trained to lower the nose as a stall approaches, but some pilots react the opposite way and that results in a stall. That low to the ground pitching down is unwise and pitching up is unwise so you'd better have the flaps configured properly or bad things can happen.

[@davidkavanagh189]

@@paulroling1781 There wasn't a last minute high G pull up. Look at the video from the ski lift. The wing pretty much just dropped and they rolled into the ground.

[@davidkavanagh189]

The possibility of a full or partial loss of slats will likely explain it. Having no slats out effectively decreases the stalling angle of the wing making an approach flown with flaps down and at normal speed very close to a real to stall condition, at least on the portion of the wing that have flaps on them.

[@FreshTillDeath56]

This is the update I was looking for. Thank you very much.

[@wokewokerman5280]

Thanks for the discussion and update, to point as usual, much appreciated....

[@luckyguy600]

You are always very professional in all your blogs. That is a ' good thing'

[@byronbailey9229]

Well spotted Juan. I flew B727 ( later B777 ) which had similar slats/flaps.

[@johncarter1137]

Thanks, Juan, be safe coming home.

[@d.t.4523]

Thank you Juan, informative as always, keep working.

[@13699111]

Thank you for the excellent update report

[@Storriesmith]

As always Juan, nice work!

[@oldmeadowvalevillager7961]

Thank You Juan . . Safe Flying . .

[@joemeyer6876]

When I saw the video, It looked like it pitched down along the pitch axis as opposed to a pancake stall. I thought they dumped the flaps to 40 all at once and the jet nosed over. It’s gonna be a real interesting voice recorder. Thanks Major

[@brentbeacham9691]

That and you have 3 living pilots. Unless they have brain injury and can’t remember.

[@glenwoodriverresidentsgrou136]

Dumping flaps makes sense if you are refusing to go around and trying to slow down, and wouldn’t that cause a nose down pitch moment? Does the trim system automatically trim nose up as flaps are extended?

[@petesmith1924]

@@glenwoodriverresidentsgrou136 No, you trim using electric trim, or hand crank it if it’s broken.

[@petesmith1924]

…that’s assuming you are hand flying the aeroplane…

[@alfredomarquez9777]

On other video, it seemed to me that one wing dips before any nose down...

[@chrisg9627]

There are so many things difficult to understand with this accident. High speed intercept of the LOC, late configuration, we are now into possible configuration protections or malfunctions. If the logic says don't deploy it will stay retracted, it will stay retracted QED. I think we need the FDR and CVR to make sense of this.

[@philipparana9225]

I mean that's how you get accidents like this. Too many forced and unforced errors.

[@Deano.1978]

Slats with auto deploy to prevent a stall can induce a nose down attitude which is evident on the video as Jaun states, then it rolls which is a stall indicator. Did they have asymmetrical slats, would that cause a pitch down and a roll/stall? Not a pilot so interested in knowing.

[@peterebel7899]

This is very interesting update! But the disaster started far more early, look at those datapoints when they were still in a NE direction coming in very steep and by doing so very fast. Whatever happened later, the crew missed to take the needed time for preparation of the approach.

[@NicolaW72]

It seemed to be that they were from the beginning of the approach "behind their aircraft" and then the ongoing miscommunication with ATC added even another increase of the workload to them. That could be a concise explanation what happened here. It wouldn´t be the first time that an accidental misconfiguration of an aircraft caused a crash.

[@peterebel7899]

@@NicolaW72 right! The only path out would have been a go around, better requesting a longer approach path first to get infront of the aircraft again.

[@2760ade]

Agreed! I'm no expert, but it definitely looks like pilot error rather than a mechanical failure. These pilots, for whatever reason, were not on top of things. Go around, reconfigure, would have been the advisable option. Shame!

[@NicolaW72]

@@peterebel7899 Indeed. The CVR should be a very important and interesting piece of evidence about what was going on in this cockpit during the crucial moments.

[@robertalbertson889]

Wow! In my opinion, that slat actuator is a slam dunk! It makes perfect sense that the flight crew was already behind the aircraft during decent and approach, they were more than likely exhausted due to the time of the flight, the miscommunications with the ATC, and then seeing the plane all of a sudden drop and begin to roll would be caused by no slats or flaps selected at the appropriate altitude and speed during the final phase of flight prior to landing! It wouldn't surprise me in the least if the flight crew just forgot to deploy the slats, causing the 737 to stall, and at an altitude of 500' gave now space or time to abort or go around, dooming the plane to drop like a rock as everyone has seen in the crash video. This finding is a huge hole in the swiss cheese for sure. The only other explanation would be a mechanical failure of the slats or it's related systems.

[@NicolaW72]

Indeed, exactly. It is not convincing to me that the slats could have retracted into this position during impact as some commenters suggest here in this forum.

[@daveshepherd7582]

Remember, slats will activate as soon as flaps do, suggesting maybe flaps were not deployed

[@robertalbertson889]

@daveshepherd7582 EXACTLY 💯 I'm thinking this will be one of the main factors in this crash! Why they just didn't go around? So sad and tragic 😥 landing fixation

[@ignorance72]

They still would've had the stick shaker before they actually stalled.

[@robertalbertson889]

@ignorance72 yes true but unfortunately, they were so low in altitude that they didn't have enough time to stop the stall. They were already nose down at maybe 500 feet? They were, unfortunately, doomed at that low altitude regardless of a stall warning or stick shaker? I think they were far behind the plane at that critical point in the flight. Hopefully, the cockpit recorder and flight data will answer most, if not all, our questions?

[@larryfriese]

I took a deep dive into the ADS-B data. After the overshoot, by 5 nm from the end of the runway, the aircraft had centered up nicely, but they appeared to be unable to stabilize the descent. It appears to have begun when they were turning onto final at around 03:24Z, 10-11 nm from the end of the runway. Before that time, they been on a stabilized ~ -3 deg descent. Afterwards, they were oscillating between ~ +1 deg and the ~ -5.5 deg flight path angle at impact. From what I've seen of this data, I doubt there was a slat failure. The cross track performance was too good to be from a jet with asymmetric high lift surfaces.

[@TyphoonVstrom]

My thought- this crew were coming in fast. They missed the initial opportunity to start deploying flaps due to airspeed on base and kept missing it all the way from base onto final. I bet they were a bit behind the aircraft the whole way through base and final as well and they just didn't notice. The video does show the aircraft with fairly significant deck angle before the pitch and roll near the end. What's the stall speed clean for this model 737? I bet they found it.

[@catherinenelson4162]

I'm sure we all love Juan's "affiliate offices"! My father had a similiar sense of humor! And Juan and other Blanco followers; if Vilnius seems strongly familiar, it's (if I remember correctly), it's where the Russian captain (played by Sean Connery), came from in the "Hunt for Red October ".

[@USNveteran]

That was a great book & movie, but pure fiction. If you want to read the real true story the name of the book is Mutiny by David Hagberg & Boris Gindin. Tom Clancy based his book on this and the vessel that was taken was a surface ship not a sub. FLY NAVY!!!

[@JohnLeaman-un4rh]

Great report JB , You are the go too man for all that is true.

[@hikari_manekineko]

Just learned something new (slats extending automatically). My extensive experience in watching Air Crash Investigation made me suspect pilot error due to tiredness. I wonder what it'll turn out to be.

[@borismedved835]

I believe that one of those videos shows a pilot moving the wrong handle changing the flaps and crashing a 737 into a street because (or at least while) she was exhausted.

[@meynelm]

Welcome to Australia. I hope you have an enjoyable visit.

[@pigdroppings]

It is summer time in opposite Australia now.

[@ghtaboma]

Don’t forget the “Vegemite”!

[@user-wl6bw3jl4n]

And Tim Tams, Lamingtons, Anzac cookies and custard tart

[@ChadDidNothingWrong]

I want to give my respects to the mechanics and engineers out there who make all this complex machinery work so reliably. It's honestly incredible considering how difficult it is to keep machinery running flawlessly. It takes an army of people who are both very intelligent and extremely competent.

[@pimacanyon6208]

indeed. How many parts are there on a 737? Thousands? Many many thousands?

[@wendygerrish4964]

Maintenance started getting 'sent out' , a decade plus or so ago. This was to cut costs of maintaining company maint employees etc wages saleries and probably made it harder to detect problems. AirNZ did this.

[@AndyG_64]

Thank you for your recognition, you're welcome.

[@sanitman1488]

Thank You. Retired AMT Pan American World Airways.

[@toddsmith8608]

​@@wendygerrish4964Indeed. Many airlines contract their heavy maintenance to outside vendors, often in locations that have very little to no regulatory oversight, in order to save money. As most of us know, you get what you pay for.

[@davidlegeros1914]

Thank you for the very technical and logical explanation of the possible cause of that accident. The video showed the aircraft rolling to one side before crashing. The loss of the slats or Kruger (leading edge) devices on one side would indeed to this. A far cry from the "Sabotage" hysteria in the Daily Mail! GOOD WORK!

[@RubenKelevra]

Yeah no wonder one wing stalled as they tried to pull up. But this still doesn't explain why they were so low... or why their slats (and possibly flaps) were not extended at all.

[@javacup912]

Wow, this indeed will generate a lot of questions, as it does look that just prior to the crash, there's a significant pitch down motion and the right roll, possibly indicating a loss of lift on the right wing, but at that low altitude, there's no recovery, as you would be 1) too slow, 2) sink rate would have to stop first, 3) the engine slow spool up time is not enough for a recovery. Any cockpit warning would have been the last thing the crew heard or saw. So tragic.

[@mattzrat]

Thanks Juan. As usual the expert eye including your A&P experience gives us the enormities a real in depth look at what happens. I wait every time till the dust settles and Brownie is on it. Agreed that piston would have bent not compressed on impact. Cheers

[@MrFezco]

Wow. Great pic of a crucial piece of evidence

[@JohnBatchelor-zb3pu]

Hi from NZ, the LE slats move to FULL extend when the flap lever moves out of position 5 to 10, or greater; that is for models -200, 300 and? -400. We used to choose flap 10 for take-off, after de-icing, to optimise wing configuration. Cheers, John. 🇳🇿

[@greglandry8248]

They may have had a flap lockout due to asymmetry issues due to a flap broken torque tube especially in the wheel well.Have changed a couple on NG .In order to unlock the system for mtc you need a pipe wrench and like airbus you need to turn the shaft in reverse direction in order to unlock the system.

[@KoiranenAerospace]

They have had flap lever in 0 position.

[@greglandry8248]

@@KoiranenAerospace For the reason mentioned above the QRH instructs to reverse the lever should you have lockout in order to unlock system .Then try again one time only.

[@KoiranenAerospace]

@@greglandry8248, they most likely had it in that position because they didn't have a clue what they were doing. Huge overspeed in intermediate approach and final approach (at stabilization altitude 60 knots overspeed) was not caused because of malfunctions, it was caused by poor airmanship and total loss of situational awaraness and in the end continuing unstable approach intentionally. If there was a malfunction, who the heck would continue approach with overspeed and would try to follow/start QRH same time? It doesn't make any sense.

[@pimacanyon6208]

thanks for the update! I have to wonder whether they could have had an equipment malfunction that had the slats extended on one side but not on the other? That would produce a tendency for the airplane to roll, no? But the more likely scenario is slats not extended on both sides, increasing the possibility of a stall at lower airspeeds, and the roll was due to the stall.

[@joso5554]

Such a sudden roll is much more consistent with an asymmetric stall.

[@Avantime]

The aircraft is smart enough to lock the slats/flaps when in transit, if any asymmetry is sensed. That's what happened with the Prime Air 767 excursion.

[@user-rl3ef4ju9k]

All those asking if the hydraulic actuator would nicely retract on impact, no, probably not.

[@byrnemeister2008]

Would be full of fluid under pressure. Very unlikely it could just collapse due to impact I would think.

[@akiko009]

I'd venture to say absolutely not. It's full of hydraulic fluid that takes time to get pushed out. It'd only retract if there's weight on it just right after the crash is all done, and assuming the hydraulic lines are cut.

[@peterebel7899]

@@akiko009 This would require free way to travel for the cylinder and all what is hanging on - very unlikely after impact.

[@peterebel7899]

100% not!

[@rkan2]

Yeah, even if the cylinder was open from the connector/hose, I would vaguer the friction/fluid pressure caused by the opening would leave the cylinder much more mangled if it were to be pushes back a lot by a very sudden impact.

[@adampaxton203]

This was a classic 737 - only the NG has the approach Idle function on the engines (which is active in the approach phase regardless of EAI position). The classic just has flight and ground idle controlled by the air ground sensors.

[@davidwebb4904]

The video does look like it stalled seconds before hitting the ground

[@alexr5557]

As ever, another brilliant analysis. Thank you! Best wishes Alex. 777/787 Instructor/Examiner.

[@KO-pk7df]

I am still in belief of your initial thoughts of hitting the approach too hot and getting and staying behind the aircraft with the crew trying to handle radio freq, capturing the GS & LOC including aircraft configuration. This discovery I believe points to that situation.

[@rjs1138]

Thanks for the update; i did wonder if, in the rushed approach, they were distracted enough not to increment the flap setting...and just ran out of lift. 🤔

[@ericmcleod7825]

Seems likely... They were high and fast so had the speed brakes out and gear down trying to get on glideslope. Then there was the distraction over the tower frequency... toss in some fatigue and they forgot about the flaps. They finally slowed down and fell out of the sky.

[@NicolaW72]

@@ericmcleod7825 Indeed, exactly.

[@nimedave]

Were they ‘on speed’ once lined up after a hot and high approach? If it was all very rushed then perhaps tired pilots could forget to lower the flaps I suppose. But all sorts of warnings would be going off for config / stall conditions. A botched go-around is plausible given how unstable the approach was in the beginning. Lots of holes here.

[@gravitymediapro]

Non-pilot here, but I awe struck by the visual similarities of the mechanical plane parts to birds of flight in nature.

[@ProctorsGamble]

Both work with the same laws of physics but on much different scales. 👍

[@NicolaW72]

@@ProctorsGamble Indeed.

[@hamsterama]

I'm a non-pilot, too. All this talk of flaps, slats, and flight controls makes sense to me, because I feed the birds and enjoy watching them. Birds have specialized flight feathers which correspond to the control surfaces of an airplane. Birds also fully extend their flight feathers when taking off, and pull their feathers back a bit when cruising. They also extend all flight feathers again when about to land, and tilt their wings (i.e. spoilers) as they land. This is easier to observe with larger birds, like crows.

[@NicolaW72]

@@hamsterama That´s really a very good observation, indeed!👍

[@chewitt6353]

The leading edges can also be extended using the standby hydraulic system. However, they cannot be retracted by the standby system.

[@militaryvehiclemarkings4696]

G’day and welcome to Australia mate enjoy your stay

[@C-Mack1972]

In addition to performing a pre-landing checklist would there not be audible warnings for a misconfigured flaps settings especially as the speeds became slower? Likewise, would you not be able to feel the airplane was handling differently than usual if indeed the flaps were not deployed as per a normal stabilized approach?

[@bullitt7544]

There are so many little holes in the Swiss cheese for me. I don't know how pilots can operate such complex machines. It is bewildering. Thank you Juan

[@johndemerse9172]

Great update Juan! Cheers from up over CYYB.

[@VickersDoorter]

Your assessments pretty-much always hit the nail on the head, I'm sure this will be at the bottom of it. This has all the hallmarks of the swiss cheese holes lining up. The miscommunication with the ATC, their being tired, their excess speed putting them behind the aircraft before finals. What is remarkable, and mercifully-so, is that at least one of the two pilots survived and yes, the black boxes will provide all the data and audio detail, but the pilot, trusting he recovers well, can say WHY and HOW they ended up how they did. That first-hand witness contribution could prove a valuable lesson for future training of commercial airline pilots.

[@fredfred2363]

So if slats are deployed automatically during a stall, why weren't they out? No flaps at low speed means the aircraft must have stalled, or, there was an asymmetric slat event that locked them out- hydraulic failure? Becoming more mysterious by the hour.

[@GeezerSqueezer]

Welcome to Aus! Great video as always 👌

[@Klaus_Bahlmann]

Thank you blancolirio, for your Videos!

[@BrianMorrison]

Very interesting. Oh dark thirty, tired, a bit fast, overshot runway centre line turning onto final. Maybe didn't get configured, but the rolling motion suggests either stall or asymmetry.

[@NicolaW72]

And add to this the increased workload caused by the miscommunication with ATC. - Yes, indeed.

[@robertd.calkins361]

Could the force of the impact have driven this LE slat back into its housing and made it appear retracted?

[@swebigmac100]

Probably not. If fully extended, it should probably have bent during the crash preventing retraction

[@dw8931]

Unless the hydraulic cylinder was ripped open as well, thus releasing all the fluid, this is almost impossible.

[@babstar99]

Post impact there isn’t an air load to force retraction.

[@markwood9755]

⁠@@babstar99Maybe during impact there is a ‘ground’ load to force retraction and if the feed lines on the ram are disconnected/ruptured to allow fluid flow the cylinder could still be intact. I am not saying that is the case but impact loads might explain the position of the actuator. On the other hand……………………….🤔mmmmmm

[@HotelPapa100]

@@markwood9755 The impact is a short, sharp force peak. I doubt that even with ripped hydraulic lines you could force the hydraulic fluid so quickly out of the cylinder.

[@chrisg9627]

And thank you for this update.

[@RoBert-ix6ev]

Licensed aircraft maintenance here, 737family type rated. And NO, slat actuators will NOT retract when hydrailuliy power is removed. And yes, on the photo at the beginning of video,the actuator is not extended. Slats move automatically in sync with trailing edge devices, ALWAYS. So,by the way, they never selected any flaps? Rushed approach? Edit: I'm not sure if I recall correctly,(it's been a while on the classic...) but I think the SMYDs won't deploy the LE devices when the flaps are "up". In my time zone its late night,definately won't get up to read AMM, someone with licence please correct me...

[@perhearkko4255]

It was pretty rushed and fast …

[@RoBert-ix6ev]

​@@perhearkko4255 It was,indeed. Note: I'm editing and adding thoughts to my comment.

[@louisvanrijn3964]

Could be. No one is invulnerable for human faults.

[@blancolirio]

Correct.

[@NicolaW72]

@@louisvanrijn3964 And it wouldn´t be the first time that an accidental misconfiguration of an aircraft would led to a crash.

[@merlin51h84]

Another great update on a possibly worrying failure. Great also to have you still doing your thing in my backyard! Thanks Juan.

[@justinjwolf]

If I'm recalling correctly, if you put the throttles to idle with the gear and flaps up (such as for an emergency descent) and silence the alarm, it won't come back on unless you move the throttles forward and back the idle again. This has almost done in a few Boeings and there's a great story about a 747 freighter almost belly landing at SFO as told by its Captain. If this is true for the accident aircraft and they coasted all the way to final (having silenced the alarm somewhere early in the descent) and brainfarted all the checklists, they might've been in a clean configuration without any alarms. I can't imagine this is true though... there are too many holes that would have to line up for them to ignore it all the way to the crash.

[@babstar99]

@@justinjwolf the B737 does indeed have a landing config warning if F15 is selected prior gear extension and idle thrust. You also can’t silence it, super loud, impossible to miss.

[@PeterStaniforth]

Guys have taken off without setting the flaps before, so there's no reason why someone couldn't do it when landing.

[@Tom-tb9sk]

From what i've heard here in germany, they messed up quite a bit during approach, like given the altimeter at 1020 and read back 1019, got the tower freq wrong, 118.205 which they read back as 118.05 thus they never had gotten in touch with the tower and had likley been 25 Meters too low on the glideslope after coming down too steep on it. And the media and some politicians and a General of the Bundeswehr were blaming russia for that crash, assuming, the plane had been manupilated. Thanks for the update on this. After seeing this roll before Impact last week, i considered retracted flaps already.

[@Avantime]

@@PeterStaniforth It would be much more insane as they needed to slow down, and flaps add significant drag. Having the slats retracted mean they were fully clean, completely flapless. And if the accident aircraft has EFIS (a few ancient 737 classics have mechanical AH/HSI) it would display the speed tape with minimum speeds.

[@flyer617]

In light of their higher than appropriate initial speed and overshooting the localizer I suspect this was crew error. Maybe they didn't extend flaps when they should have due to the excessive speed, then forgot. Besides the data and voice recorders, the co-pilot survived, although sometimes memory isn't good after a traumatic event.

[@DR_1_1]

Lack of flaps would fit the higher approach speed and faster descent rate I guess. Apparently it's not so uncommon with freight at night, reading some posts... to gain time.

[@Mrs.RobinWilliams]

Thank you! Stay safe 🤗🙏

[@Rabenov-wq8qy2qg5t]

The high speed they had on the approach, the attempt to capture the glide path from above - the pilots probably didn't even think about setting the flaps. When I saw the machine fall out of the air in the video, I immediately thought of the flaps.

[@johnman8554]

Nah, they would not lower gear without flaps.

[@jerrydeanswanson79]

So Juan...when you are off galavanting (jet-setting...smiles) are you ever able to get out of the hotel to see the sights and stuff?

[@blancolirio]

Yep, briefly. Long enough to get this bad haircut...lol

[@Craigkenyon-yc3tk]

Juan fellow pt121 here. SYD. Buy a Hunter Valley tour, zoo, hiking trail starting from zoo ferry stop, rent bike in Manly, ?blue mountains, easy enough to rent a car and gad about. Pizza at “The Australian”, rooftop bar just down from the Oz, enjoy!

[@thehighwayman78]

​​@@blancolirio"kid, if they're looking at your hair, we're in trouble" Harrison Ford to Mark Hamill when he was worried about inconsistencies in his hair between takes...

[@Dilley_G45]

​@@blancoliriosee the blue mountains... three sisters... Springwood

[@Dilley_G45]

​@@blancolirioLemme know next time you're there. I'm based near Sydney. Happy to buy you a coffee

[@Lodifireengineer]

A hydraulic piston, if disconnected from the hydraulic system is easy to manipulate in and out. Once that hydraulic assembly was ripped loose from the hydraulic lines, the piston would no longer be held in place by hydraulic fluid and may no longer be in the same configuration as it was when the plane was still intact.

[@Flinno-k8w]

But I would expect an object eating through the wing like a mast hit the slats first, destroying them , moving into the wing pretty far before severing the hydraulic lines. And hit afterwards would be against destroyed, mangled flats that rest against the wing. Pistons full of oil with hyydraulic lines can be manipulated in and out, but any violent= FAST hit against it would last milliseconds, and if you have a oilfilled piston with a small hole as exit is basically a damper and is exceptinally hard to move back in milliseconds. .

[@NicolaW72]

Thank you very much for this very informative update!👍👍👍 That would be indeed a disturbing discovery that the slats were probably not extended. That would mean that the Aircraft was misconfigured for the approach and landing. There happened some well-known crashes where the Aircraft was not properly configured for the take-off, which ended in disasters - the last one was Spanair Flight 5022 in Madrid in August 2008. An accidental misconfiguration of the aircraft for approach and landing happened the last time with Yeti Airlines Flight 691 in Nepal in January 2023. So such a misconfiguration wouldn´t be unique. The CVR will be indeed a very important source to see why this happened if it was the reason for this crash. This could be a really important finding.

[@garyhalmbacher6875]

A misconfigured Northwest Airlines flight crashed in Detroit years ago. Flaps were not set at takeoff.

[@NicolaW72]

@@garyhalmbacher6875 Indeed, it was Northwest-Airlines-Flight 255 in August 1987. And some very similar crashs happened, too: Delta Airlines Flight 1141 in Dallas/ Fort Worth in August 1988, LAPA-Flight 3142 in Buenos Aires in August 1999 and Mandala-Airlines-Flight 91 in Medan/ Indonesia in September 2005.

[@saldun2603]

Thank you so much for your dedication to understanding, diligence and rapid response information. Onward 🌈 to blue skies

[@jasonwhite1069]

Interesting, and sad! My very first thought, the first time I saw the video of the accident, was, "It looks like they stalled". Juan...please keep doing what you do...this is my go-to channel.

[@MikeDudley-b4b]

Well explained deductive observation Jaun, thank you. Mike.

[@tomdchi12]

If there was slat asymmetry at that moment in the video (short final i I understand correctly) would the pilot flying have enough aileron and rudder authority to counter it? Also what are the chances that the actuator could change position as part of the impact of the crash?

[@joso5554]

Very low but still rather far from the runway threshold… There definitely was an approach slope increase in the last 5/10 seconds, possibly related to the rapidly decreasing airspeed and the slats anomaly situation. Seems to have been a rushed, poorly stabilized approach at the end of a long workday and the lowest circadian cycle point…

[@glennllewellyn7369]

It will be interesting to see further revelations.

[@Celsian]

Am I remembering wrong or are leading edge slats on the 737 also the reason for the recent runway excursion landing by Prime?

[@Tod_oMal]

In the Prime it was a misalignment config, it did not say they were not extended. That's a difference.

[@jimpalmer1969]

The Prime accident was a 767-300. Systems wose a very different airplane.

[@ericbrink5071]

Yeah I think that was leading slat whatever the opposite of symmetrical Is.. i still dont see how that would cause runway excursion.. is that because they had to land going faster and reverse thrust maybe inop?

[@Celsian]

@@jimpalmer1969 Ah yes, a 767, oops. Thanks!

[@Celsian]

@@ericbrink5071 Blacoliriro observed that they spent very little time in the air working the problem. He suggested a go around would have given them much the time they needed to get the checklist out, run through it a time or two and then prepare for a faster landing if they could not get the leading edge flaps symmetrical.

[@flyingjeff1984]

Juan, the biggest fright I ever had was shortly after takeoff one day, the FO had a brain fart and fully retracted the slats/flaps. Thankfully, I had the habit of watching the other pilot's actions and grabbed the handle immediately. At low speed, it would be over quickly.

[@MeppyMan]

Yikes. I assume the FO went off for some additional training?

[@farayidarlingtonchaparadza20]

​@@MeppyManAs well as a change of undergarments

[@chrisnoname2725]

@@MeppyManwhy would you need retraining because of a once off error? There is no individual that it’s a lack of understanding or a habit.

[@leokimvideo]

This explains so much about that crash without unnecessary drama, only issue I see is where is the fire damage?. Juan be careful in Sydney, the power grid is maxxed out because renewable energy is failing us bad. Already been a number of CBD blackouts. Also maybe follow up on the Australian tail strike story at the Bathurst car race. There's legal action against the stunt pilot Hayden Pullen. He's up for a serious wilful disregard of aviation rules.

[@stringpicker5468]

I call BS on the power issue and I live in NSW. there was a blackout in far west NSW due to a line failure today, but no load shedding. Any potential failure is caused by 4 clapped out coal fired power stations privately owned and not maintained. Keep your poxy politics for another channel.

[@MarkPentler]

@@stringpicker5468 amen. these people are always the one shoving their agendas into ANYTHING. It's always *that* side.

[@SaberToothBicycle]

Looked like the aircraft was nose high when it first came into view, and appeared to experience stick pusher events on the video. This would explain why. If the slats were either not extended, or accidentally retracted

[@NicolaW72]

Indeed.

[@richard--s]

What if there was icing on the approach? (maybe untreated?) could that prevent some slats from going out?

[@ChollaJJ]

Jaun, just a question, in your first picture of the part in the dirt, is that a glove there in the photo ? Thanks

[@reefkeep2]

On the 737 200 the slats are out full at flaps 10 so I say the 400 model is close the same

[@Tod_oMal]

Same for the 737-800.

[@rkan2]

Since the 737-100 the flight controls have remained pretty much the same, even if almost everything else has changed physically, except for the shape of the fuselage sections.

[@johnmorris7815]

The 73 slats were always the Achilles heal hence the slat position indicator that you showed on your video, this was an addition after early slat asymmetry problems. Add to that the lack of roll authority at low speed and you get another 737 disaster.

[@rogerveon3631]

The roll rate was intentionally decreased on the B737-200 by disabling flight spoilers. Early B 737 had a much higher roll rate.

[@timmiser]

I recall from your earlier report that they were coming in relatively hot and were aggressively slowing down on their final approach. I can't imagine them not using the flaps to help them slow down so would be interesting to know if other flap/slat actuators were retracted or not. Also curious, are the slats only controlled automatically by the flaps lever position in the cockpit (that you showed) or is there a way of controlling the slats independent of the flaps? In other words, can you deploy flaps without deploying the slats if the system is working correctly?

[@NicolaW72]

Probably no. But there´s the hypothesis in this comment section that the slat actuator could have forced back into the retract position by the impact. But it should be easy to verify by the investigators if this was the result or the reason for the crash.

[@Flinno-k8w]

They where above 228knts IAS till very late in the approach, and that's above flaps 1 speed i think.

[@NicolaW72]

@@Flinno-k8w At least they were definetely at the beginning of the approach beyond the flaps extension speed.

[@michaeldantoni4292]

Are the LE slats , numbered 1-6 from left to right, as are the engines ? The display panel makes it look the opposite of that. Just curious.

[@williampotter2098]

Thanks Juan. Your extensive knowledge and quick study is incredible.

[@ruky1969]

I do believe that aircraft went below minimum and struck a power cable tower right on final look at the approach chart.. even thus you maybe right on your explanation, taking in consideration the kind of accident that actuator may or may not retract, that airplane hit the ground with an extreme force that the minimum you could expect is to consider an actuator stay at it position.. but once again you maybe right...

[@blaircooper3549]

Nice update. Do you think there was a sudden slats incongruity with a system failure on short final. At what point on approach do you go flaps 40? I fly a m20 j every so often now

[@catalinalb1722]

Hello will you cross Australia on motorbike like you did in the US? ☺️ 👍

[@ryanthggygh7716]

Good morning Juan Love your channel, love what you do and how you are trying to prevent people from making the same mistakes. This 737 crash, unstable approach and rolling movement just before impact. They were coming in hot. At the speed they were at, wouldn’t the leading edge slat not be a factor? If they were slower I could see it being retracted a factor. Need those voice recordings.

[@anniechrisbendy6000]

EXCELLENT WORK....... TRUELY EXCELLENT 👏🏻👏🏻👏🏻👏🏻👏🏻👏🏻👏🏻 fantastic foto , explanation ..... 🇬🇧

[@ansonstelmak9783]

Another great followup Juan

[@jonchowe]

Would the lack of flaps/slats made the plane easier to roll?

[@Wannes_]

It'd have made it far easier to stall Stalls usually aren't nicely symmetric, meaning one wing will dip first, which would be looking like a roll

[@rkan2]

The amount of pitch up combined with a stall at 170kts indicated seen on the videos would have made no sense with a proper landing configuration with flap30. With flap15 or less it makes a lot more sense.