Beech Premier down on apprach RWY 15 WMSA

[fdr]

Kuala Lumpur - Bad VLJ accident, 8 on board, 2 on ground, just north of Shah Alam, at the entrance of a housing complex. US rego, N28JV, operated locally. Flight from Pulau Langkawi to Subang, WMSA, Kuala Lumpur.

R.I.P. (https://www.thestar.com.my/news/nation/2023/08/17/aircraft-crashes-near-elmina)

[magyar_flyer]

Can not post them but few graphic dashcam video are making the rounds.
Apparently straight nose dive to impact. Aircraft seems structurally intact. Odd

[sleeper]

https://youtu.be/4iA8RL2xx1I

one link several vieuws.

[FUMR]

From what I saw on FR24 the aircraft was established on final for runway 15 and roughly 3 miles out when it suddenly veered off track. Seemed very sudden.

[Giboman]

looks way too fast to be in a stall

[physicus]

assuming 30fps video in the link above, they were impacting at about 210m/s (~750km/h / ~400 kts). Doesn't look like gear or flaps are out either. Certainly not looking like a stall recovery at those speeds...

[physicus]

Looked at the ADS-B data on RealTraffic. Looks like an uneventful ILS/GS capture on AP with MCP alt set to 2500ft at 185kts GS, then descending on the glide with matching descent rate for an established approach, then reducing speed 150ish kts. On passing FL010 (1000ft at std pressure alt), ground speed dips to 144kts, and position starts to turn hard right. No more data updates after that except for position data, showing tight right turn, perhaps a stall.

They certainly didn't finish the approach check as the missed approach altitude wasn't set on the MCP (remained 2500ft til the end, should be 3000ft for LOC/ILS15). Could be a hint that some other critical items were forgotten, like flaps, and gear (missing from the video posted above as well).

What's the clean stall speed of a Premier 1?

Can't seem to attach a zip file with kml/csv data - PM me if interested.

[Miles Magister]

More interesting though is what is the stall speed at heavy weight with 8 people on board. This is just something to be aware of.

[1southernman]

Single pilot owner/operator?...I believe this Beech was produced to compete with Citation, etc....

[FUMR]

Single pilot owner/operator?...I believe this Beech was produced to compete with Citation, etc....

Was reported as 2 crew, but that of course excludes what qualifications the RHS may have had.

[1southernman]

Was reported as 2 crew, but that of course excludes what qualifications the RHS may have had.
Thanks for the info and that's true about RHS...Just saw that report and it also says a charter flight?...IIRC US FAR 135, charter with pax, used to require 2 crew on SP Citations...SP ok for charter freight (fun flying) and Part 91 ops...

[JanetFlight]

Clear video with final seconds of flight...forgive my personal humble point of view... Almost seems deriberately... weird!!

https://twitter.com/i/status/1692174661684167065


twitter.com/i/status/1692174661684167065

[ETOPS]

Looks like gear and flaps up and high speed. Why no recovery inputs?

[megan]

Aircraft was N28JV operated by Jetvalet Sdn Bhd, also operate a G4 and Beech 4000, established during the pandemic by ex airline folk.

[physicus]

Here are a couple of plots. The aircraft was equipped with decent ADS-B out capability which includes BDS6,0 messages. This means we know what the MCP altitude and headings were set to. Hence my post above that the MA alt was not set at above 1000ft AGL (stable approach criteria) so likely a check was missed. IAS is also transmitted in these messages and we therefore know the speed decayed to as low as 144kts before a sudden increase in geometric descent rate. Note the geometric rates are calculated from the ADS-B position messages, not from the barometric rate, and are thus the only data points providing vertical speed info during the last 10 seconds.


https://cimg2.ibsrv.net/gimg/pprune.org-vbulletin/1100x1092/n28jv_8aec48b67ecd4c6a8467cd10e7f2865b6eb041a3.jpg

[WhoFlungDung]

Clear video with final seconds of flight...forgive my personal humble point of view... Almost seems deriberately... weird!!

https://twitter.com/kltrafficupdate/status/1692174661684167065?ref_src=twsrc%5Etfw%7Ctwcamp%5Etweetembe d%7Ctwterm%5E1692174661684167065%7Ctwgr%5E429f3dfdfe48c333ed e9ac2eee393f8aaf16f65f%7Ctwcon%5Es1_&ref_url=https%3A%2F%2Faviation-safety.net%2Fwikibase%2F343582

What is the flash of light from the tail of the aircraft at the 2 second mark?

[physicus]

I think that's a sunlight reflection off the leading edges of the wings. Seems to roughly align with sun being overhead slightly to the left (check shadows of road markers).

[megan]

Just been reading the report on a Bombardier Challenger 605 accident where they overcooked the turn to final.At 1318:09, the stick shaker engaged again followed immediately by the stick pusher engaging, the airplane was on a southeasterly heading when it entered a rapid left roll. The airplane was in a 111° left-wing-low bank angle at 1318:11 and 1 second later it was in a 146° right-wing-low bank angle and an approximate 30° nose-low attitude, just before the airplane impacted terrain and a post crash fire ensuedSeems a lot of right bank on, wonder if similar.

[physicus]

this Premier accident doesn't look like anyone "overcooked" anything - whatever that means. Looks more like simply forgot flaps and slowed down into a stall in a heavy airplane. Controlled FLight outside the enveloPe - CFLOP. To mint a new term...

[atakacs]

Looks like gear and flaps up and high speed. Why no recovery inputs?
And seemingly very high speed.
I guess it had full suite of FDR ?

[zegnaangelo]

doesn't look like a stall though?

[FUMR]

Just been reading the report on a Bombardier Challenger 605 accident where they overcooked the turn to final.Seems a lot of right bank on, wonder if similar.

It was also my first thought. I went on FR24 and realised it wasn't the case. It was established on a standard (presumably ILS) approach. There were no turns involved immediately prior to the upset.

[fdr]

Looks like gear and flaps up and high speed. Why no recovery inputs?

I'd suggest the images support the gear being down, it is not clear but looks like pixels similar to gear position.
The aircraft is not slow for the phase of flight, irrespective of its flap setting, if anything I would appear to be quite fast if a stable approach was intended.
A lateral rolloff may be from an asymmetry of a flap, it s too fast to be likely a VMCA event, No TRs, but an asymmetric lift dump might give such a roll off. With 2 pilots it shoudn't be a physiological event, but it can still occur. The DFDR should survive, hopefully they have enough parameters to determine the cause promptly.

Was this doing charter work? it doesn't appear to be on an FAA AOC or transferred by ICAO 83 bis to a CAAM AOC, and they don't seem to have an CAAM FAOC, so hope it was legitimate FAR 91.

[fdr]

this Premier accident doesn't look like anyone "overcooked" anything - whatever that means. Looks more like simply forgot flaps and slowed down into a stall in a heavy airplane. Controlled FLight outside the enveloPe - CFLOP. To mint a new term...

Not seeing any data to support that hypothesis. The stall speed is not going to be an issue, this isn't a stall evant, it is a lateral rolloff for undetermined reasons. The great oracle GOOGLE gives a Vs at "108 Kts clean", which is about what would be expected. The stall speed for most small-medium jets clean vs dirty are not that different, other than some high performance flap systems like the Falcon 20, 10, 50, 900 etc, For a Lear, Westwind, Hawker, the TE flaps don't shift the stall speed that much, some but not the 40+ kts needed in this case for 1g stall.

The approach to Subang RWY 15 is usually a protracted affair, not often you will get a shortened approach, unlikely they were doing a short base, certainly not from the Langkawi direction.

[fdr]

Thanks for the info and that's true about RHS...Just saw that report and it also says a charter flight?...IIRC US FAR 135, charter with pax, used to require 2 crew on SP Citations...SP ok for charter freight (fun flying) and Part 91 ops...

This aircraft doesn't appear to be on an AOC with the FAA to the best information that is available (If it was a charter, and not on AOC, then it would be "interesting"). It appears to be operated under a time share agreement structure, rather than a fractional ownership means... §91.501(c)(1) & (d). §91.23 will make for interesting reading unless this "investment Cooperative" is intended to be a loss leader.
(c) As used in this section—

(1) A time sharing agreement means an arrangement whereby a person (https://www.law.cornell.edu/definitions/index.php?width=840&height=800&iframe=true&def_id=132cc06e7d7e62fc0e6480c63251185f&term_occur=999&term_src=Title:14:Chapter:I:Subchapter:F:Part:91:Subpart:F:9 1.501) leases his airplane (https://www.law.cornell.edu/definitions/index.php?width=840&height=800&iframe=true&def_id=ee9803083700896cd85aff74cb4f95ea&term_occur=999&term_src=Title:14:Chapter:I:Subchapter:F:Part:91:Subpart:F:9 1.501) with flight crew to another person (https://www.law.cornell.edu/definitions/index.php?width=840&height=800&iframe=true&def_id=132cc06e7d7e62fc0e6480c63251185f&term_occur=999&term_src=Title:14:Chapter:I:Subchapter:F:Part:91:Subpart:F:9 1.501), and no charge is made for the flights conducted under that arrangement other than those specified in paragraph (d) (https://www.law.cornell.edu/cfr/text/14/91.501#d) of this section;



(d) The following may be charged, as expenses of a specific flight, for transportation as authorized by paragraphs (b) (3) and (7) and (c)(1) of this section:

(1) Fuel, oil, lubricants, and other additives.

(2) Travel expenses of the crew, including food, lodging, and ground transportation.

(3) Hangar and tie-down costs away from the aircraft (https://www.law.cornell.edu/definitions/index.php?width=840&height=800&iframe=true&def_id=8e9caab04f792d93d0738c9d3290164e&term_occur=999&term_src=Title:14:Chapter:I:Subchapter:F:Part:91:Subpart:F:9 1.501)'s base of operation.

(4) Insurance obtained for the specific flight.

(5) Landing fees, airport (https://www.law.cornell.edu/definitions/index.php?width=840&height=800&iframe=true&def_id=48135f7b500227b0896c0a3bae41467a&term_occur=999&term_src=Title:14:Chapter:I:Subchapter:F:Part:91:Subpart:F:9 1.501) taxes, and similar assessments.

(6) Customs, foreign permit, and similar fees directly related to the flight.

(7) In flight food and beverages.

(8) Passenger ground transportation.

(9) Flight planning and weather contract services.

(10) An additional charge equal to 100 percent of the expenses listed in paragraph (d)(1) (https://www.law.cornell.edu/cfr/text/14/91.501#d_1)of this section. [(1) Fuel, oil, lubricants, and other additives. ]

[1southernman]

Did a little research on the type...This info may not be completely accurate...The "1" was replaced by the "1A" in 2006 to correct many issues including braking and to make other refinements...N28JV was a "1" I believe but my source says all should've been upgraded to "A" specs...Hull losses on both versions occurred mostly in app/ldg and mostly from pilot error ( a Nascar owner at Oshkosh)...Didn't see any involving LOC in flight BUT it was a quick search so as I stated may not be accurate...Btw in the video it looks to me like they were belly up or close to it at impact...FDR just now see your input and several mentions of "lift dump" and WOW issues on ldg are in the hull losses reports ...Supposedly corrected in upgrades...

[fdr]

Did a little research on the type...This info may not be completely accurate...The "1" was replaced by the "1A" in 2006 to correct many issues including braking and to make other refinements...N28JV was a "1" I believe but my source says all should've been upgraded to "A" specs...Hull losses on both versions occurred mostly in app/ldg and mostly from pilot error ( a Nascar owner at Oshkosh)...

That was Jack Roush, in 2010. The NTSB put that down to distraction during a G/A at low level, he believed he was conflicting with a Piper Cub, overshot the c/line and added thrust more or less by muscle memory, not by the gauges, got stall, stick pusher but RW stalled at low level. This case, is not low speed for this aircraft.

...Btw in the video it looks to me like they were belly up or close to it at impact...FDR just now see your input and several mentions of "lift dump" and WOW issues on ldg are in the hull losses reports ...Supposedly corrected in upgrades...

WOW failure airborne would lead to fairly high AOA, and could give a tip stall if the path was being maintained, the AOA will rise rapidly, to maintain the reqd total lift for the path, and any roll tendency the ailerons will have reduced effectiveness due to the AOA, [Boeings... aileron effectiveness increases with speed brake rise... slightly different dynamics. Airbus/Boeing FBW, the gain scheduling is altered and the PI control loop stops most of that effect in normal laws. Airbus infamous OEB 117 comes to mind...]. It is possible that inadvertent ground spoiler may end up with a roll off, and a stick push going on, would be recoverable if aware of it, roll authority by rudder and asymmetric power still exists, but it could be challenging, and quite a surprise.

[1southernman]

That was Jack Roush, in 2010. The NTSB put that down to distraction during a G/A at low level, he believed he was conflicting with a Piper Cub, overshot the c/line and added thrust more or less by muscle memory, not by the gauges, got stall, stick pusher but RW stalled at low level. This case, is not low speed for this aircraft.



WOW failure airborne would lead to fairly high AOA, and could give a tip stall if the path was being maintained, the AOA will rise rapidly, to maintain the reqd total lift for the path, and any roll tendency the ailerons will have reduced effectiveness due to the AOA, [Boeings... aileron effectiveness increases with speed brake rise... slightly different dynamics. Airbus/Boeing FBW, the gain scheduling is altered and the PI control loop stops most of that effect in normal laws. Airbus infamous OEB 117 comes to mind...]. It is possible that inadvertent ground spoiler may end up with a roll off, and a stick push going on, would be recoverable if aware of it, roll authority by rudder and asymmetric power still exists, but it could be challenging, and quite a surprise.

The following about the Premier from another forum ,"Airline Pilot Central", The Google found for me :)...

Can deploy in flight. 3 boards per side. System is locked except for takeoff, (for an abort), and unlocked prior to landing. System is separate from speedbrakes, and power will not cause a retract. On back of pedistal, it is a t handle that is illuminated white when armed. A unlock switch,an emergency manual lock release, and Warning placard about not deploying in flight are beside it. Alarm sounds if handle moves without deployment. Early Premiers had to have weight on wheels, but this was later changed after a rash of runway overruns after failed deployment. There was an SB issued to convert the older systems.

[Teddy Robinson]

Flap asymmetry / late deployment and attempted retraction ?

[physicus]

fdr they did a straight in, no base. Thanks for looking up the stall speeds - never operated small bizjets, surprised to see their Vs doesn't change dramatically with flaps.

https://cimg3.ibsrv.net/gimg/pprune.org-vbulletin/767x625/screen_shot_2023_08_20_at_07_33_18__479b0dfd97ff2646196a8f3f 38aefcdf3f0bfc09.jpg
https://cimg1.ibsrv.net/gimg/pprune.org-vbulletin/716x557/screen_shot_2023_08_19_at_07_38_29__12247ce89ccbd2e9c598a3ae 7da3743709ad1c1b.jpg
https://cimg2.ibsrv.net/gimg/pprune.org-vbulletin/644x517/screen_shot_2023_08_19_at_07_38_59__34acdd483a149cc7100f87c2 b16ced11c42f6fe0.jpg

[Concours77]

Just been reading the report on a Bombardier Challenger 605 accident where they overcooked the turn to final.Seems a lot of right bank on, wonder if similar.
if that's TahoeTruckee, it was a circle to land. Overshot base, then final, tightening the turn, PF deployed spoilers. RIP...
circling left Stall, Spin. Don't remember a right roll reversal. Was that in the NTSB report just released??
you post:
​​​ "111 degrees left wing low, one second later, right wing 146 degrees low."

T-38?

[Concours77]

doesn't look like a stall though?
At the last, it was spinning, the inversion was almost complete.
So yes, Stalled....imo

fdr they did a straight in, no base. Thanks for looking up the stall speeds - never operated small bizjets, surprised to see their Vs doesn't change dramatically with flaps.


That's not a long base, with a too tight turn to final?
Long downwind with a too tight turn to base?
Dunnint look like a straight in.
Middle pic shows long final for the RW... did he forget he was straight in, then a desperate right turn to final for the freeway? On the Twitter, his right turn looked very slow ... recovery, then a second Stall then Spin, and done?

[The Messnger]

From the information available the approach speed for this aircraft is in the region of 120KIAS +/- for conditions.
From the data available it was high on glide slope and fast all of the way down final so you could deduce from that the thrust would be at idle in an effort to get back on slope and correct the speed.
VFE 200KIAS for initial approach VLE200KIAS VFE 170 final approach.
Approach data distance from touchdown:
9nm 2575ft 192kias (below G/S)
7nm 2300ft 184kias (200ft above G/S)
5nm 1800ft 178kias (300ft above G/S should be considering a missed approach-too high too fast 58kts above approach speed)
4.3nm 1500ft 166kts (300ft high 46kts fast)
4nm 1250ft (50ft high 154kts appears like nose down manoeuvre to correct G/S, high rate of descent, when the aircraft should be stable in full approach config. 120KIAS )
Somewhere shortly after this stage I would think an attempted missed approach was made and the speed too fast for a stall. Thrust would be advanced from presumably idle to G/A thrust. The aircraft never stopped descending from this time and commenced a turn to the right. From this knowledge could we consider some sort of failure as thrust was increased? Did the right engine fail to produce expected thrust and was rudder not applied correctly for an asymmetric situation? The aircraft in the video supports this as the bank angle to the right went through 90 degrees and at impact was inverted. In my time as a check Captain on heavy jet I have seen more mistakes during handling a missed approach especially with an engine inoperative than on a take off with an engine failure at V1. The reason is that pilots on approach tend to be in landing mode rather than rehearsing a missed approach with a failure, of some sort, in their mind before landing. Just a thought!

[fdr]

fdr they did a straight in, no base. Thanks for looking up the stall speeds - never operated small bizjets, surprised to see their Vs doesn't change dramatically with flaps.

https://cimg3.ibsrv.net/gimg/pprune.org-vbulletin/767x625/screen_shot_2023_08_20_at_07_33_18__479b0dfd97ff2646196a8f3f 38aefcdf3f0bfc09.jpg
https://cimg1.ibsrv.net/gimg/pprune.org-vbulletin/716x557/screen_shot_2023_08_19_at_07_38_29__12247ce89ccbd2e9c598a3ae 7da3743709ad1c1b.jpg
https://cimg2.ibsrv.net/gimg/pprune.org-vbulletin/644x517/screen_shot_2023_08_19_at_07_38_59__34acdd483a149cc7100f87c2 b16ced11c42f6fe0.jpg

That track is the normal one from Langkawi to Subang, overhead Ipoh and onto the approach at CE, Caledonian. The approach and flight appear nominal all the way to the lateral excursion.

The change in the status of the aircraft was abrupt, which still suggests a major aerodynamic upset issue such as inadvertent lift dump deployment resulting in a tip stall and subsequent departure, or a medical event with the pilot, which seems remote, it appears there were probably 2 pilots.

FLAPS
On flaps and stall speeds, for heavy jets, we almost invariably have LE devices of some sort, slats (Airbus, B737 outer, B757,767, 777, 787), Kruegers (B737 inboard, B727), flexible Kruegers (B747). If the wing is relatively straight, you can get away with simplified systems of TE flaps only, but the LE is normally a fairly healthy radius to give a benign stall, and there is a need for some additional twist if the wing is swept, or some span wise flow control like fences, vortilons, VG's etc. A good read on the subject is:
Rudolph, P. K. C. (1996). High-Lift Systems on Commercial Subsonic Airliners. NASA Contractor Report 4746 (Issue September). https://doi.org/NASA Contractor Report 4746. Bottom line is the slats on our heavy jets are very good at their job, which is to improve stall behaviour, reduce stall speed through much higher CL/AOA. Most heavies will schedule an auto slat extension at high AOA when the wing is clean, a swept wing that doesn't do that, or that it occurs with some asymmetry will give a really good roll off at the stall break. Flaps are part span on most aircraft, slats, and slats/kruegers are effectively full span. High performance TE flaps that are multi element, and increase surface area will produce a fairly good stall speed reduction, but it is still pretty limited in the extent of change. The flaps only configuration increases the inboard CL for a given attitude, by both increasing the camber of the section, and the AOA, but as the overall lift is affected by the component CL of the total wing, keeping the inboard section below stall AOA means the outboard section loses AOA and therefore CL, but this gives better lateral control authority so is tolerable.

Flap behaviour can be enhanced, guys like James Ross at NASA Ames (nowadays "Jim"), John C Lin at NASA HQ and many others have worked on many different mechanisms to improve foil performance.

[fdr]

At the last, it was spinning, the inversion was almost complete.
So yes, Stalled....imo


That's not a long base, with a too tight turn to final?
Long downwind with a too tight turn to base?
Dunnint look like a straight in.
Middle pic shows long final for the RW... did he forget he was straight in, then a desperate right turn to final for the freeway? On the Twitter, his right turn looked very slow ... recovery, then a second Stall then Spin, and done?

The aircraft in the video is not in an incipient spin or a developed spin, it is a lateral departure from normal controlled flight. You may wish to argue that point, but there is no evident yaw in the video, so incipient is unlikely, and developed spins exhibit rates of pitch roll and yaw at the same time, (unsteady may alter 1 or 2 of those momentarily as they reverse or are just unsteady). The recent C-152 accident on this forum gives a graphic demonstration on the incipient spin condition...

[megan]

What angle of bank do folk think this shows?


https://cimg8.ibsrv.net/gimg/pprune.org-vbulletin/143x125/ab264_ee2926e24c5908562084922ddbb97e31bcf3438b.png

Clean stall 108 knots quoted above by fdr would give a stall at 153 knots with 60° angle of bank, physicus notes a speed of 144 knots prior to the descent. Spoilers come into effect at 10° of aileron input should that imply anything.

[Concours77]

The aircraft in the video is not in an incipient spin or a developed spin, it is a lateral departure from normal controlled flight. You may wish to argue that point, but there is no evident yaw in the video, so incipient is unlikely, and developed spins exhibit rates of pitch roll and yaw at the same time, (unsteady may alter 1 or 2 of those momentarily as they reverse or are just unsteady). The recent C-152 accident on this forum gives a graphic demonstration on the incipient spin condition...

Disagree...no full recovery from the initial Stall. What you think is missing Yaw is expressed in the Nose dropping like a stone. What looks like a "turn" to the right is a fully Stalled and Spinning aircraft. Completely out of control, both wings irrecoverably Stalled. The velocity convinces us the aircraft is in a leisurely very high speed turn. I think no...depending on thrust, completely ballistic...imo

Pitching....Up, tightening the radius. Rolling, Right; Yaw, Right.
"Looks like". But just a ballistic, high speed trajectory, Spin. Not all Spins are vertical, or even (down, steep). One can be climbing steeply, and spinning....

[Concours77]

That track is the normal one from Langkawi to Subang, overhead Ipoh and onto the approach at CE, Caledonian. The approach and flight appear nominal all the way to the lateral excursion.

The change in the status of the aircraft was abrupt, which still suggests a major aerodynamic upset issue such as inadvertent lift dump deployment resulting in a tip stall and subsequent departure, or a medical event with the pilot, which seems remote, it appears there were probably 2 pilots.

FLAPS
On flaps and stall speeds, for heavy jets, we almost invariably have LE devices of some sort, slats (Airbus, B737 outer, B757,767, 777, 787), Kruegers (B737 inboard, B727), flexible Kruegers (B747). If the wing is relatively straight, you can get away with simplified systems of TE flaps only, but the LE is normally a fairly healthy radius to give a benign stall, and there is a need for some additional twist if the wing is swept, or some span wise flow control like fences, vortilons, VG's etc. A good read on the subject is:
Rudolph, P. K. C. (1996). High-Lift Systems on Commercial Subsonic Airliners. NASA Contractor Report 4746 (Issue September). https://doi.org/NASA Contractor Report 4746. Bottom line is the slats on our heavy jets are very good at their job, which is to improve stall behaviour, reduce stall speed through much higher CL/AOA. Most heavies will schedule an auto slat extension at high AOA when the wing is clean, a swept wing that doesn't do that, or that it occurs with some asymmetry will give a really good roll off at the stall break. Flaps are part span on most aircraft, slats, and slats/kruegers are effectively full span. High performance TE flaps that are multi element, and increase surface area will produce a fairly good stall speed reduction, but it is still pretty limited in the extent of change. The flaps only configuration increases the inboard CL for a given attitude, by both increasing the camber of the section, and the AOA, but as the overall lift is affected by the component CL of the total wing, keeping the inboard section below stall AOA means the outboard section loses AOA and therefore CL, but this gives better lateral control authority so is tolerable.

Flap behaviour can be enhanced, guys like James Ross at NASA Ames (nowadays "Jim"), John C Lin at NASA HQ and many others have worked on many different mechanisms to improve foil performance.









What is that RW in the distance beyond the long descent. ??
(middle pic)

[1southernman]

Just considering the video with no other info I see an airplane flying, clean( can't be sure, not enough pixels), not stalled, nose down, rolling right and maybe an "oh feces" pull at the end...I'm going with a spoiler/lift dump issue due to failure or mismanagement...My final answer...maybe :)...

[Concours77]

Just considering the video with no other info I see an airplane flying, clean( can't be sure, not enough pixels), not stalled, nose down, rolling right and maybe an "oh feces" pull at the end...I'm going with a spoiler/lift dump issue due to failure or mismanagement...My final answer...maybe :)...

Nose Down? Hmmm... how is the track yawing right? If he was trying to turn right, nose would not be down, crossed controls. .
I think he was madly trying to roll left, ailerons not effective... Rudder not effective... elevators not touched.
Pilot is making my case. No controls, not any effort to stop the roll or turn is visible, airframe totally ballistic... no attempt to arrest a 60 degree bank?

[fdr]

Nose Down? Hmmm... how is the track yawing right? If he was trying to turn right, nose would not be down, crossed controls. .
I think he was madly trying to roll left, ailerons not effective... Rudder not effective... elevators not touched.
Pilot is making my case. No controls, not any effort to stop the roll or turn is visible, airframe totally ballistic... no attempt to arrest a 60 degree bank?

...

how is the track yawing right?

Concours, are you referring to a track change to the right with an aircraft that is in a right bank? That is not indicative of yaw, it is indicative of a turn rate.


I think he was madly trying to roll left, ailerons not effective... Rudder not effective... elevators not touched.

madly trying to roll left, ailerons not effective...

There is a probability that the roll control is to the left by the pilot, that is a reasonable supposition, but if the wing has already reached a near stall AOA say, through the inadvertent deployment of the ground spoilers, then the ailerons are very ineffective in roll, in fact can be expected to reach an adverse roll state rapidly, causing the bank to steepen.

Rudder not effective...

What do you base that statement on? If the AOA is high, then rudder effectiveness increases in the secondary effect. There is no discernible evidence of the rudder being applied to the left in the images I see, perhaps you have a better photo that shows left rudder applied.

elevators not touched.

When the window all goes green instead of blue, the instinctive response to a pilot who is not proficient in aerobatics and having awareness of the attitude of the aircraft, and why it is in that attitude, is to pull back, so you may well be correct to mention elevators, but I would contend that they are probably touched, increasing the g loading of the aircraft. At a high bank angle, the AOA stability of the aircraft, what we ordinarily term static speed stability is that the aircraft will attempt to recover towards the same AOA that it is in trim at. In this case, the aircraft is trimmed somewhere near 140K(IAS/CAS?) wings level, roll into a 60 degree turn, and the aircraft will have a pitch rate to attempt to retain the same AOA, and that means the g loading will increase, it ends up in a spiral dive in such a case. That is without touching the elevators, that's just an aircraft that behaves as a dart does, having positive static stability. In this case, the PRE1 type I understand has a stick pusher, and it will act against that to provide a nose down pitch input force to the elevators. That itself doesn't particularly degrade the flight path angle, having a high bank angle that continues to increase guarantees the aircraft is going into a steep nose down attitude rapidly. FWIW, the videos that exist so far are showing an aircraft that was likely already approaching the point of being unrecoverable at about 13-14 seconds into the video, impact happens out of frame at around 18 seconds. The maths on that is pretty straightforward, the only question is what the AOA did to enter the predicament. Any recovery required reducing the bank angle, and then applying as much g as was available to raise the flight path vector, and that also needs to resolve the issue that the aircraft went into a high bank in the first case. Elevators themselves as a recovery item are not relevant to the recovery; if the roll was related to a stall from a ground spoiler issue, then the only way to recover roll authority is to break the stall, and that comes from the stick pusher in part, and pilot action hopefully as well. Elevators didn't cause this, stick shaker should help, and I cannot blame any pilot at low level with a lot of buildings coming into the window to not pull on the prong, even at high bank angles... even with a stall warning going off.

Wake Turbulence. Wake turbulence is always able to mess up a lighter aircraft all by itself, but this particular airport has painfully generous wake separation that is applied religiously. If there was an aircraft "the same day" in front it would be a surprise. [this is true for approaches, for takeoffs, at this airport I have more than once had to advise ATC we would take a delay of X seconds for wake separation on departing traffic]

A bank of 60 degrees by itself does not indicate that an aircraft will reach a stall AOA, but the flight path angle will degrade if the achieved lift doesn't match weight, so the pitch will increase. Being at 90 degree bank doesn't stall a wing, being at or above critical AOA does. Will the plane permit level flight at 140kts 60 AOB with a stall speed of 108Kts? nope.

In this case so far, the indication is of a lateral departure from controlled flight that then resulted in a severe dive angle, and at the time that the aircraft started to go pear shaped, it is not pulling enough g to get to stall AOA, If anything, the aircraft was at a relatively high energy point and needed to slow down to the Vref for the approach, speed itself was not the issue, something upset their coffee, enough to get a wild bank angle going.

As far as data goes, the aircraft won't have a DFDR, it will have a CVR, probably still a Fairchild/L3 2100-1010, which should provide some information. For the investigators at CAAM, there is a test and readout capability for those in Jakarta, one of few around in the area. The flight display info may give some data, and the ECU for the engines, but the CVR will give RPM anyway, and there is little likelihood that engines are related to this incident. The ADSB-out will give good information to support the video and CVR.

P.S:

at t=1s. the aircraft is wings level, at t=4s, AOB is around 45, at t=6s AOB is greater than 60, that is a reasonable roll rate, but well within the roll authority of the aircraft in normal conditions. From around t=1s to t=13s the situation has gone from a relatively normal flight path to unrecoverable, with impact about 3-4 sec later. In that time, the pilot has to determine the cause of the upset while mitigating the effect it has on the flight path. That's about the same time that Laura 004's crew had to intervene and stop the loss of the B763 way back in the 90's. Might seem easy in an arm chair, but with an aircraft that has a mind of its own, not so much. That is a similar time that the Yeti crew had to work out what the ninny in the RHS had done by feathering both engines instead of closing the power levers in Nepal.

P.P.S.: The lift dump switch is the T-handle on the center console well behind the throttles, behind the rudder trim. It is well out of the sight line of the pilot. but has its own set of alerts and warnings.


https://cimg6.ibsrv.net/gimg/pprune.org-vbulletin/1500x1000/21_1500x1000_2_9a754b21365195360f22cd2f10becb0de69231e3.jpg

[fdr]

What is that RW in the distance beyond the long descent. ??
(middle pic)

The runway in the middle image of the ADSB data on Google is WMSA/SZB/Subang/Lapangan Terbang Sultan Abdul Aziz Shah/Sultan Abdul Aziz Shah Airport. It was the former international major airport for KL, until the opening of KLIA. It is still an international airport but is primarily a domestic, corporate and regional international airline airport. It has an ILS to RWY 15 which sometimes works, and it was the site where the B747F of Flying tigers ended up in the side of a hill from the opposite direction many years ago (ended in tears). It's actually a pretty good airport, and reasonably easy access to downtown, where the food is excellent (it's Malaysia, the food is excellent everywhere). The RMAF have some of their airlift based out of there on the west side of the airport, lots of MROs on the SW and E side of the airport. Excellent FBO there, Skypark, both sides of the airport. Old terminal had a fire years back just as we parked a visiting B747, new terminal is not bad at all, but Skypark is one of the best FBO's in SE Asia, like Wings over Asia in Seletar.

[Concours77]

The runway in the middle image of the ADSB data on Google is WMSA/SZB/Subang/Lapangan Terbang Sultan Abdul Aziz Shah/Sultan Abdul Aziz Shah Airport. It was the former international major airport for KL, until the opening of KLIA. It is still an international airport but is primarily a domestic, corporate and regional international airline airport. It has an ILS to RWY 15 which sometimes works, and it was the site where the B747F of Flying tigers ended up in the side of a hill from the opposite direction many years ago (ended in tears). It's actually a pretty good airport, and reasonably easy access to downtown, where the food is excellent (it's Malaysia, the food is excellent everywhere). The RMAF have some of their airlift based out of there on the west side of the airport, lots of MROs on the SW and E side of the airport. Excellent FBO there, Skypark, both sides of the airport. Old terminal had a fire years back just as we parked a visiting B747, new terminal is not bad at all, but Skypark is one of the best FBO's in SE Asia, like Wings over Asia in Seletar.
Did not expect that... you a writer? That is quite nice. I remember that wreck...and Lauda, and the Bombardier with that terrifying video... (some survived!)

So Beech was making a turn. To final? The Twitter vid shows a Stall as he turns...he didn't recover it, and a second one caught him out...imo

So much for straight in...Or...?
Thanks Captain

[Concours77]

"Concours, are you referring to a track change to the right with an aircraft that is in a right bank? That is not indicative of yaw, it is indicative of a turn rate."

Not if the aircraft is Stalled, and it is not a "turn". The aircraft is falling, not flying. Can't prove it. The increasing roll rate, the falling off of the nose, the descent looks like 1g. All elements of a Spin? Just about vertical at impact...

[fdr]

... you a writer?
Nope, but done a fair share of accident investigations over 43 years. flew in this area in different militaries, and airlines and in my own jets. Have 2 cats there still...

So he was making a turn. To final, ?
No, it is essentially a straight in approach. Ipoh to CE gives a slight left turn to pick up the LLZ, The approach was nominal until the plane darted off to the right, and that was away from the runway.

The Twitter vid shows a Stall as he turns...
The video shows a turn that is away from the desired course, and that cause is the 64 dollar question, what makes the plane turn unexpectedly? It doesn't have T/Rs, so they are out of the picture, an asymmetric flap may be ugly, and an inadvertent lift dump is high on the suspects. If single pilot, incapacitation would be there too. Its VFR, it isn't an instrument failure... These suggest a stall of the RH wing tip is an precipitating factor, and that suggest a limited number of options. The plane hasn't stalled n the turn, it is a stall that has caused a turn, and the stall is not from inadequate airspeed, or erroneous ADC's, GS and IAS correlate well in the start and that indicates the ADC was still good. This plane doesn't stall at 1g at 140kts...

he didn't recover it, and a second one caught him out...imo.
Not sure there is a second one, the cause of the upset doesn't appear to be resolved at any point, this started bad and never got better.

So much for straight in...Or...?
The approach is straight in to RWY15, and they would have been more or less stabilised to start with, but a little fast. Configuration is still not determined, but there is no reason that the config would have directly affected the lateral attitude of the aircraft, so is no material to the event.

Thanks Captain
welcome.


"Concours, are you referring to a track change to the right with an aircraft that is in a right bank? That is not indicative of yaw, it is indicative of a turn rate."
Not if the aircraft is Stalled, and it is not a "turn". The aircraft is falling, not flying. Can't prove it. The increasing roll rate, the falling off of the nose, the descent looks like 1g. All elements of a Spin? Just about vertical at impact...

Not if the aircraft is Stalled, and it is not a "turn". The aircraft is falling, not flying.
Being stalled doesn't mean you are falling, it means the wing has reached or exceeded the stall AOA, At that point, maintaining level flight isn't going to occur. unless you have vectored thrust, or buckets of excess thrust, (an extra 360 or a monster Pitts will sit happily on its prop vertically, as does an F-35B or a Harrier, and when serviceable even a Yak-38 Forger will (but only till it busts). In aerobatics, stall is just another flight regime, sometimes it is needed to achieve another manoeuvre, sometimes it is what is avoided by varying g load... it's nothing special in it's own right, and the plane doesn't fall out of the sky or become uncontrolled just because of that. A stall with a yaw rate, or with asymmetry of forces will get more interesting, but it is just a AOA that needs to be managed, nothing much more than that, if you time and airspace to do so.

The increasing roll rate, the falling off of the nose, the descent looks like 1g. All elements of a Spin? Just about vertical at impact...

Interestingly, the roll rate is modest throughout this event, it just doesn't get reversed to reduce the bank angle. This event doesn't have any high rates of roll at all, it is remakable that the rates are very genteel. Almost any aircraft out flying will achieve far better than 30 degrees a second sustained roll rate after a couple of seconds of a full control deflection, even a Boeing... This event is a relatively low roll rate, and, yes, it has a steep bank angle in the final moments, but that is around 10 seconds from the start (video time covers multiple takes of the scene). Whatever happened was not arrested in time by the pilot(s), and yet was not that catastrophic. For a full spin entry, the roll rates will usually be over 90 degrees a second pretty quickly (some planes will flaff about and take forever to achieve a spin entry... some are really quick) The yaw rates into a spin will be pretty high, above 30 deg/s pretty quickly, and pitch rates will also be fairly good, same or so. Unstable spins are quite disorienting, as. are aircraft that go from upright to inverted and back again quickly... but this case, there is no appreciable yaw, the bank angle has not been mitigated, ad the plane cannot maintain a flight path in such case and so the flight path angle will steepen. Off the video, it looks like it is near vertical bank at impact, or slighty over (90-100) and around -15 pitch. (The wing bus 20 degree sweep, and from almost abeam, the tip is still forward of the wing root... ) The pitch isn't the primary problem, the bank is "what the problem is". Ordinarily, the IAS would have accelerated rapidly in an event like this, around 10-15K/s sort of minimums, and that has not happened, which is why I would suggestive lift dump actuator lengths will be telling in this case. If a flap had blown up asymmetrically, causing a roll, the drag reduces partially and the descent would result in a speed increase, that hasn't appeared to occur on the first glance of the ADSB data. Drag appears to have increased... not reduced.


F4 Flat Spin


Watch at around 3:20 onwards for a fail to recover Great footage before that on wing rock, and departure with immediate recovery
F4 Wing Rock, Departures and Loss of chute

EXTRA SPIN


PITTS

PITTS INVERTED


Tomahawk

[Uplinker]

Has it been established whether there were one or two pilots?

Perhaps a passenger was "having a go" at the controls and inadvertently stalled it by making much too rapid control movements while flying slow. This might have happened by them suddenly looking up and seeing the road on their right and 'lurching' the yoke towards it, (and maybe pulling back as well), thinking it was the runway - before PF could stop them - at which point the aircraft stalled and dropped a wing into a full spin. And then there was only very limited altitude to recover.

RIP

[Concours77]

fdr... Many thanks. Your expertise and experience are quite evident. I am learning at a rapid rate.

What I meant to say was -1g. Accelerating descent at g. The final descent has elements of a barrel roll, that would be 1g, yes?
The AC had some lift or the descent would have been "falling".

The timing would tell. My surmise "rudder ineffective" has to do with a lack of recovery from roll right. Pilot would apply aileron and rudder in coordinated fashion. That didn't happen, or it did with no success. If the aircraft is not stalled, we are stuck with CFIT, in some form or fashion.

The only Pitch we would see if not Stalled would be NU? The "turn" is tightening, but not remarkably...stopping the descent is priority one...

Exonerating pilot(s) would involve conclusions such as incapacitation (single pilot) or ineffective controls, something broke. I lean toward the latter. The flight path is not unusual if aerobatic, but knife edge is not desirable here. Only tightening the turn would maintain altitude, as the aircraft sinks for want of (banked) lift? Pilot lost consciousness and slumped the yoke? The (seeming) lack of recovery from the Stall induced departure from track is a puzzle.
Thanks again for your posts, they are superb... conc

[fdr]

Has it been established whether there were one or two pilots?

Perhaps a passenger was "having a go" at the controls and inadvertently stalled it by making much too rapid control movements while flying slow. This might have happened by them suddenly looking up and seeing the road on their right and 'lurching' the yoke towards it, (and maybe pulling back as well), thinking it was the runway - before PF could stop them - at which point the aircraft stalled and dropped a wing into a full spin. And then there was only very limited altitude to recover.

RIP


Has it been established whether there were one or two pilots? RIP
Not definitively, but is was originally reported as 2+6




Perhaps a passenger was "having a go" at the controls and inadvertently stalled it by making much too rapid control movements while flying slow. This might have happened by them suddenly looking up and seeing the road on their right and 'lurching' the yoke towards it, (and maybe pulling back as well), thinking it was the runway - before PF could stop them - at which point the aircraft stalled and dropped a wing into a full spin. And then there was only very limited altitude to recover.

There is no evidence of an abrupt control input, the roll rates that have been seen are well within the control authority of the aircraft if only caused by the pilot input.
The only indication of a possible stall is the gentle roll rate away from a clearly in view 10,000' runway that is 3 miles ahead, and looks like a runaway not like a road intersection.
Roll if related to a stall in such a manner is not consistent with a normal lateral authority or a lift altering issue that has caused part of the wing to reach stall AOA.
This aircraft is not in a spin, with incipient or full. Are we still referring to the accident of N28JV at Kuala Lumpur? This aircraft has rolled to the right to a high bank angle, at a gentle rate, it has not pitched up, down or otherwise, the back end of the plane is tracking the pointy bit, there is no significant yaw.... so no spin. Thee is no wing rocking, there is no pitching either up or down, there is an apparent static speed stability response of the aircraft, this being an aircraft that has stick pusher, not evidently in effect. Try: google "spin".

[fdr]

What I meant to say was -1g. Accelerating descent at g. The final descent has elements of a barrel roll, that would be 1g, yes?

To achieve -1g takes a considerable pitch down rate in level flight, at 140kts, roughly around 8-9 degrees nose pitch down per second. Nothing in the video suggests the plane achieved any g loading that was much removed from 1g. The gz if it had been recorded before the roll would be around 0.995 or so and quite stable. If the plane had been built with slats, the value would be just below 1g, and the sum of gx and gz would give a vertical vector slightly below 1g. The plane is trimmed at the start to a given AOA that will achieve that g loading. If the lift vector is inclined, the flight path angle will degrade to a steeper flight path. If the stick pusher activates, the aircraft is "pushed" to a lower AOA, and will pitch to achieve that AOA, appropriate to the stab trim + elevator forces.

A barrel roll requires more than 1g to do unless you desire to end up in a vertical dive recovery, at which point more than 1g must be applied, or the flight terminates at the interface of tin and planet. A barrel roll is normally a modest positive g manoeuvre. It describes a smooth path inclined along an imaginary cylinder, which is a nice manoeuvre, it requires coordinated roll and pitch rates to make it smooth. To get the nose to come up from the initial entry requires more than 1g, otherwise it becomes a spiral dive. When inverted, the pitch rate is reduced, if the shape is desired to be smooth, and the airspeed is normally lower than entry. In a propeller aircraft, it also requires coordinated rudder as the trim condition is changing with airspeed. A tight barrel roll may be done at well above 1g, it can be done up to the g limit of the plane but normally it is a 2-3g+/- manoeuver. 1g will achieve a near vertical dive pretty quickly. The g loading changes throughout a smooth barrel roll, but is normally at least slightly positive at the top, which is the controlling condition for an appropriate g load and consequent appropriate roll rate. A constant roll rate at varying g loads requires constantly altering aileron inputs, It is a nice coordination exercise, mores with a big radial engine or large prop, or draggy biplane.


The AC had some lift or the descent would have been "falling".

The AC derives lift from the wings and fuselage, tail and even the engine nacelles. If vertical resultants equal weight the plane will fly in level flight, if vertical resultant forces exceed mass, the aircraft will increase in height. Aircraft don't "fall" as such, unless dropped from a crane or otherwise. A helicopter that has mast bumped and removed the rotor will "fall".

My surmise "rudder ineffective" has to do with a lack of recovery from roll right. Pilot would apply aileron and rudder in coordinated fashion. That didn't happen, or it did with no success. If the aircraft is not stalled, we are stuck with CFIT, in some form or fashion.

The rudder is almost always effective, below transonic speeds. The rudder is not affected greatly by AOA, it becomes relatively more effective than the ailerons as AOA increases, as aileron effectiveness reduces. There is no evidence here of a rudder input so far, normally the rudder doesn't get much exercise in flight in a jet. Some jets will apply a turn coordination rudder input in some conditions, and in this case, I would assume but do not know as a fact that a yaw damper is installed in the aircraft. Most jets end up with a need to have a yaw damper, and if the wings are swept, then that becomes near certainly a necessity. A yaw damper failure can cause an initial roll like this, and may be a factor, however aileron or rudder remain available to compensate, they are normally very limited authority [UA585, US427 are cases where a failure mode of a yaw damper resulted in a large deflection of the rudder by the initial input of a yaw damper]

The only Pitch we would see if not Stalled would be NU? The "turn" is tightening, but not remarkably...stopping the descent is priority one...

Speed stability will ensure the aircraft is wanting to pitch to a constant AOA, and that would be ANU. Stopping the descent when at a near vertical bank requires removing the bank first, and if that is due to a stall, then the stall must be resolved to gain control authority.

[megan]

Has it been established whether there were one or two pilotsYes, both named and photos published.

[Concours77]

To achieve -1g takes a considerable pitch down rate in level flight, at 140kts, roughly around 8-9 degrees nose pitch down per second. Nothing in the video suggests the plane achieved any g loading that was much removed from 1g. The gz if it had been recorded before the roll would be around 0.995 or so and quite stable. If the plane had been built with slats, the value would be just below 1g, and the sum of gx and gz would give a vertical vector slightly below 1g. The plane is trimmed at the start to a given AOA that will achieve that g loading. If the lift vector is inclined, the flight path angle will degrade to a steeper flight path. If the stick pusher activates, the aircraft is "pushed" to a lower AOA, and will pitch to achieve that AOA, appropriate to the stab trim + elevator forces.

A barrel roll requires more than 1g to do unless you desire to end up in a vertical dive recovery, at which point more than 1g must be applied, or the flight terminates at the interface of tin and planet. A barrel roll is normally a modest positive g manoeuvre. It describes an smooth path inclined along an imaginary cylinder, which is a nice manoeuvre, it requires coordinated roll and pitch rates to make it smooth. To get the nose to come up from the initial entry requires more than 1g, otherwise it becomes a spiral dive. When inverted, the pitch rate is reduced, if the shape is desired to be smooth, and the airspeed is normally lower than entry. In a propeller aircraft, it also requires coordinated rudder as the trim condition is changing with airspeed. A tight barrel roll may be done at well above 1g, it can be done up to the g limit of the plane but normally it is a 2-3g+/- manoeuver. 1g will achieve a near vertical dive pretty quickly. The g loading changes throughout a smooth barrel roll, but is normally at least slightly positive at the top, which is the controlling condition for an appropriate g load and consequent appropriate roll rate. A constant roll rate at varying g loads requires constantly altering aileron inputs, It is a nice coordination exercise, mores with a big radial engine or large prop, or draggy biplane.




The AC derives lift from the wings and fuselage, tail and even the engine nacelles. If vertical resultants equal weight the plane will fly in level flight, if vertical resultant forces exceed mass, the aircraft will increase in height. Aircraft don't "fall" as such, unless dropped from a crane or otherwise. A helicopter that has mast bumped and removed the rotor will "fall".



The rudder is almost always effective, below transonic speeds. The rudder is not affected greatly by AOA, it becomes relatively more effective than the ailerons as AOA increases, as aileron effectiveness reduces. There is no evidence here of a rudder input so far, normally the rudder doesn't get much exercise in flight in a jet. Some jets will apply a turn coordination rudder input in some conditions, and in this case, I would assume but do not know as a fact that a yaw damper is installed in the aircraft. Most jets end up with a need to have a yaw damper, and if the wings are swept, then that becomes near certainly a necessity. A yaw damper failure can cause an initial roll like this, and may be a factor, however aileron or rudder remain available to compensate, they are normally very limited authority [UA585, US427 are cases where a failure mode of a yaw damper resulted in a large deflection of the rudder by the initial input of a yaw damper]



Speed stability will ensure the aircraft is wanting to pitch to a constant AOA, and that would be ANU. Stopping the descent when at a near vertical bank requires removing the bank first, and if that is due to a stall, then the stall must be resolved to gain control authority.
It is difficult to suss looking at the AC belly on, but the AC looks well NU relative to the flight path. If the departure involves the shaker/pusher, I could see a version of Colgan here. Highly stressed, pilot pulls on the pusher, it becomes a push pull match, pilot gaining purchase on the firewall with the right foot and rudder, well, it has happened. Legacy carrier, (Continental/Colgan)

I can't see that flight path as aerodynamic flight....the turn radius is miniscule. Is there an RTL? Cuz the rudder could be keeping the nose tracking

[fdr]

It is difficult to suss looking at the AC belly on, but the AC looks well NU relative to the flight path. If the departure involves the shaker/pusher, I could see a version of Colgan here. Highly stressed, pilot pulls on the pusher, it becomes a push pull.match, pilot gaining purchase on the firewall with the right foot and rudder, well, it has happened. Legacy carrier, (Continental/Colgan)

I can't see that flight path as aerodynamic flight....the turn radius is miniscule. Is there an RTL? Cuz the rudder could be keeping the nose tracking


It is difficult to suss looking at the AC belly on, but the AC looks well NU relative to the flight path. If the departure involves the shaker/pusher, I could see a version of Colgan here. Highly stressed, pilot pulls on the pusher, it becomes a push pull.match, pilot gaining purchase on the firewall with the right foot and rudder, well, it has happened. Legacy carrier, (Continental/Colgan)
Colgan was a unique event, and was predominately an aerodynamic event associated with icing. The response by the US Senate was as bizarre as the rest of the goings on about the accident. An upset from icing being incorrectly mitigated will end in tears unless there is a seriously large amount of airspace between the plane and the planet. There is very little that is linear in ice upsets. The remarkable issue about icing is the inability of the profession to get the point across to everyone that should be aware of the issues. I have personally stopped 2 aircraft, one being a B737 and one being a B744 from being flown with serious contamination on the wings, one by asking to be deplaned, and I was a supernumerary check pilot, and the other by taking photos of the wings and the airport manager in the same frame and advising him I would use that as evidence if the aircraft was not de-iced/anti-iced. This event however, does not have any evidence of a HMI breakdown, other than the fact the plane got disassembled in a noisy manner.

I can't see that flight path as aerodynamic flight....the turn radius is miniscule. Is there an RTL? Cuz the rudder could be keeping the nose tracking

I can't see that flight path as aerodynamic flight...
That is close to a word salad; the flight path is the resultant of all forces acting on the body, which are rather well known, since Otto L took up jumping off Sandhills. It was within the planets atmosphere, so it is aerodynamic as a result. However, if you mean it is not following a commanded path, then that is an interesting question, and the answer is, it is following the normal behaviour of a vehicle with the forces on it that are evident. That is, lift vector & thrust. That the path is undesirable is the problem, it hasn't broken physics, it is only a question as to why the path is in the direction it is.

the turn radius is miniscule.

Not sure if you are saying that it is a tight turn, e.g., a very small turn radius:
[adjective: miniscule

1.
extremely small; tiny.
"a minuscule fragment of DNA"]

If so, the radius of turn is consistent with a modest g load from the speed stability (as the bank is close to vertical, the aircraft stability acts to return the plane to the in trim AOA, and that means increasing the g loading normally, in this case however, the IAS did not increase significantly, which is why I am thinking the extension length of the lift dump actuators will be germaine to the event. A roll would come from a split flap case, but then the drag would be reduced, and I would have expected to see an IAS excursion, and higher g loading from the speed stability than appears to be the case. Increased drag while affecting AOA comes from lift dumps... Of course, of a thousand different causes, including a pilot just deciding to have a heart attack or TIA or other event may result in a bad day, the latter is less likely with a 2-pilot crew, but is not completely ruled out, (recall JAL's DC-8 @ Haneda)

Is there an RTL? Cuz the rudder could be keeping the nose tracking

If you are referring to a turn coordination function ["RTL?"] of the rudder, if the aircraft has a yaw damper, then quite often (but not always) a coordinator function will be incorporated. They are of limited authority, and are usually not a linear function, the requirement for coordination is a 3rd order effect dependent on bank angle. At near vertical bank, a turn coordinator won't help much on doing anything. The aerodynamic forces and stability behaviour of the aircraft are consistent with the video, in pitch, and yaw. The anomaly here is if the pilots wanted to land on a perfectly serviceable 10,000' of concrete, then the turn is anomalous, and not removing the bank before the smoke starts issuing forth is presumable an undesired outcome.

Any aircraft rolled over to vertical bank will have the nose lower as a natural outcome, the aircraft lateral-directional stability will require that to occur. If you had a really big rudder, then that can be mitigated, but comes with the risk of resulting in a spectacular departure from controlled flight, as it introduces a yaw rate into the state of the aircraft, and that gives the potential for a very rapid stall and flick. That can be a fun manoeuvre in a Pitts or an Extra, is less enjoyable in a swept wing jet at 500' AGL.

At the risk of repeating myself, this aircraft diverges from a nominal flight path with little obvious intervention. As the attitude would be obvious to anyone in the aircraft, this was not due to missing the cue of attitude, it suggests the crew were unable to intervene meaningful to the divergence. There are not many items that will do that, and fewer than normal in this case, it doesn't have T/Rs, so they are off the list. The other item that is known is the IAS(CAS?) and GS of the aircraft, these are from different sources, but agree within reasonable margins. They indicate that the aircraft had entered a fairly impressive dive, and yet IAS and GS have not appreciably increased. That is of interest, as if the roll divergence was related to a split flap, then drag would be reduced, and a speed excursion would be likely to be observed. In the absence of that, it would appear that drag increased, and that can't be from thrust reversers (T/R's) as they are not fitted, and the only other interesting option is the lift dump. Lift dump activation in flight will give an increase in AOA to maintain a flight path with the altered CL that exists, and that then puts the tips of the wings up towards the stall AOA, in fact the whole wing, but the point of interest is the tips. The PRE1 has two vortilons on each outboard wing section, and that indicates that during flight test, the stall behaviour was needing an improvement, although, unless a substantial twist existed in the wing, the need for span wise flow control is obvious, and readily managed by many different aerodynamic mechanisms. Aileron responsiveness is dependent on AOA, and at high AOA, an initial roll that is relatively benign becomes problematic with the use of ailerons. The vortilons are effective, but they still don't stop a left roll input causing a further AOA increase of the RH wing tip, which is already high from a right roll (damping effects). Of all airports, Subang is up there in the least likely to have a wake encounter for a landing aircraft. Have only taken jets in there a couple of hundred times, and the operational frustration is the opposite to being given inadequate wake separation.

The dive is a normal body response to the extended period of flight with a high bank angle, the plane has done e xactly what it is designed to do from a lateral-directional and longitudinal static stability viewpoint.

This plane is an FAA certified aircraft, TCDS (A00010WI), and also holds EASA TC (A.073). It is certified under 14 CFR Part 23 up to amendment 52. The Part 23 Subpart B provides a fairly basic set of stability and control requirements, but they are nothing unusual. These include §23.2135 Controllability, §23.2145 Stability, §23.2150 Stall characteristics, stall warning and spins.
§23.2145 (a)(1) requires "[color=#000000]Have static longitudinal, lateral, and directional stability in normal operations". Pretty vanilla stuff, but that is what the plane will have at all times, unless there is a biggly intervention to that. 965, as amended by Amendments 23-1 through
23-52

P.S.:

There are some excellent books out there on aircraft aerodynamics, stability & control. Fixed wing is easy, rotary S&C is far more fascinating. There is a modest amount of maths involved, but the concepts are not that hard, and the maths can be broken down into components that each make sense. Leishman, Pamedi, Perkins & Hage, Robert Nelson, Duncan, Chudoba, Abzug & Larrabee, Michael Cook, Jan Roskam, and many others have written on the subject. For helo's, Ray Prouty is hard to beat, and Wayne Johnson adds the maths. Padfield, etc make helo S&C interesting. Standard control concepts apply to all systems, and planes are just systems in the end, there is some neat physics, but it is able to be modelled and understood pretty well, and that means we can back drive the event to what is possible to determine what must have occurred.

[Concours77]

RDR. Rudder travel.limiter. Constrains rudder sweep with increase in AirSpeed...

CVR. All I've got. You are a Gold mine... you could bump all but two or three of the best AV writers.

[fdr]

Rudder travel.limiter. Constrains rudder sweep with increase in AirSpeed...

RTL. OK. AIrbus incorporates a rudder travel limiter, which featured in the accident to the A300-605R AA 587 on the coast at JFK in 2001. It is intended to reduce the torsion and bending loads on the vertical stabiliser, but it perversely increases the sensitivity of the rudder instead for the pilot. The Boeing rudder ratio system restricts the control surface movement for the control input, Airbus reduces the limit that the pedals can move but keeps the rudder-pedal ratio the same. Very few if any light jets, VLJs or even medium jets have any limiter on the rudder, beyond pilot awareness. At any time, an entry of full rudder can be applied and will lead to high loads on the vertical stab, and if applied in a sequence like AA587 has a high likelihood of taking the tail off any aircraft. AA-587 had a series of near full reversals of the controls, even within the rudder limit system, but these resulted in high sideslip angles, and alternating torsion-bending loads that the aircraft is not designed or certified to survive. We nowadays teach pilots (sometimes) a bit more about certification to stop the assumptions leading to bad days.

Just because the aircraft is below Va doesn't mean that mishandling or handling in the face of lack of knowledge cannot bust an aircraft.

We have managed to take the tail off aircraft just from gust loads, being kind to aircraft is a good idea.

This is not relevant to the KL accident, the tail remained on the plane, and the system has almost certainly not got a rudder ratio or rudder throw/deflection/travel limiter.

P.S.: Air Asia 8501 report from NTSC states a causal factor was the RTLU unit failure, which is not supportable by the evidence. The RTLU will bring up an ECAM fault message, that indicates as well a FAC fault, FAC 1 and then later FAC 1&2. The actions by the flight crew in attempting to reset a minor fault resulted in the FCS eventually reverting to Alternate law, this is a modest downgrade of functionality, but the crew then appeared to become spatially disoriented, and the aircraft and occupants had a bad day. The RTLU may have been contributory, but any other fault causing a minor degradation would appear to have been likely to repeat the outcome, the problem was the spatial disorientation when the pilot was needed to actually be in the loop in flight. For AA-587, the rudder limited was cited by the NTSB as a contributory factor, I would contend the failure of industry awareness of certification criteria was a greater latent failure that came to the fore. The flight crew responded to a wake encounter with inputs that exceeded the design and actual strength of the aircraft, while following in part the training that the industry was giving at that time.

[JanetFlight]

Having in mind one of the passengers was a local mediatic malaysian politician, could we also consider some sort of ilicit intervention, hijack, suicide, etc?

[physicus]

Concours77 You say CVR is all you have? I'd assume there's EFIS/ECC logs that can be extracted by the manufacturers of said units. And I can provide you with the ADS-B data I used for the plots above. While of limited use, it helps preclude some scenarios. PM me if you want that data.

[Uplinker]

OK. (forgive me, I cannot view the video for some reason).

So, if there were no significant flight control surface movements, then there was no 'piloting' going on. But why?

Engine failure and they both looked in and PF forgot to look outside, control the flight path and keep flying?

Pilot incapacitation, and their hand pulled back the Starboard engine thrust lever as they passed out?
If so, where was the second pilot, and why did they not react?

What would an uncorrected engine failure do at this phase, in this aircraft? How much yaw/roll would result?

[IanW]

The named SIC doesn’t appear to be “Certificated” according to the FAA Airmen database. The named PIC held an A/RA390S rating, probably issued late March 2023

[Concours77]

Whatever happened, the result was asymmetry. There is some chatter re interference w/ crew, or homicide, suicide. However, the crews' credentials want a look?
The upset was radical and seemingly immediate....

"The U.S. NASA (https://en.m.wikipedia.org/wiki/NASA) Aviation Safety Program[2] (https://en.m.wikipedia.org/wiki/Aircraft_upset#cite_note-nasa-asp-2)[3] (https://en.m.wikipedia.org/wiki/Aircraft_upset#cite_note-usg-3) defines upset prevention and upset recovery as to prevent loss-of-control accidents due to aircraft upset after inadvertently entering an extreme or abnormal flight attitude."

[sycamore]

Looking at the cockpit photo there are 2 `yellow-topped knobs next to the throttles..are these `engine `run/stop` controls,as they seem to be `unguarded` and could be inadvertently operated...?
Also,if the aircraft had `speedbrakes`,where/how are they operated...SWITCH,OR LEVER...?

I have spent a few years doing airtests on ex-mil jets which have speedbrakes/airbrakes on the wings or fuselage,and I would always check their operation for symmetric extension,no yaw/roll,at low speeds before high speed extension...
To me this looks like a hurried approach,and then maybe a tecnical failure,ie,flap asymmetry,same for airbrakes/lift dump,leading to the roll...or inadvertant engine shutdown..

[Concours77]

As many times as I've looked at the video, seems to be an aircraft descending nose down, followed by an excursion Starboard, then a roll, then more Starboard. Looked like a Stall from controlled flight. Trending to knife edge still in a turn, then, two seconds before impact, a rapid roll and near vertical impact. The speed looks to be 160-180 knots...(wag) the lack of apparent attempts to recover is disturbing...
A case can be made that there was an initial (partial) recovery from the Stall, but with a wing dropping off starboard, followed by a descending right turn... perhaps a secondary Stall.

[moosepileit]

I don't see stall AOA.
Looks like controlled flight.

Hope not.

https://youtube.com/shorts/FzBtF-RZwAU?feature=share

[fdr]

The named SIC doesn’t appear to be “Certificated” according to the FAA Airmen database. The named PIC held an A/RA390S rating, probably issued late March 2023

The aircraft is an SP-IFR aircraft, so no Co-pilot was legally required. The company appears to be operating §91.501(c)(3)(1), which is pretty vague on other requirements although §91.23 will be of interest to the feds undoubtedly. Under §61.55. the SIC may in fact have a qualification that has not shown up as yet in Oklahoma's records.

[fdr]

As many times as I've looked at the video, seems to be an aircraft descending nose down, followed by an excursion Starboard, then a roll, then more Starboard. Looked like a Stall from controlled flight. Trending to knife edge still in a turn, then, two seconds before impact, a rapid roll and near vertical impact. The speed looks to be 160-180 knots...(wag) the lack of apparent attempts to recover is disturbing...
A case can be made that there was an initial (partial) recovery from the Stall, but with a wing dropping off starboard, followed by a descending right turn... perhaps a secondary Stall.

As many times as I've looked at the video, seems to be an aircraft descending nose down, followed by an excursion Starboard, then a roll, then more Starboard. Looked like a Stall from controlled flight. Trending to knife edge still in a turn, then, two seconds before impact, a rapid roll and near vertical impact. The speed looks to be 160-180 knots...(wag) the lack of apparent attempts to recover is disturbing...
A case can be made that there was an initial (partial) recovery from the Stall, but with a wing dropping off starboard, followed by a descending right turn... perhaps a secondary Stall.

but with a wing dropping off starboard, no wing fell off. How language is used counts, 2/3rd of the visitors to these pages have English as a second language.
near vertical impact. The last images of the aircraft are taken from a distance away, but clearly show the wing tip of the aircraft still obscuring the wing root, and with a 20 degree sweep wing leading edge, that indicates the nose down pitch is less than 20 degrees. The bank angle at that point is near vertical, but the exact body attitude can be determined, this is nowhere near "nearly vertical". Kinematically, it would be close to impossible to achieve a near vertical descent without achieving rates of roll and pitch that arise only with autorotation or coupling, and none of that occurred here, all of the rates are well within normal control derivatives.
As far as a stall goes, the known speed at the start is well above a stall that doesn't include aggravation. The flight path is consistent with having a problem that exceeds slightly the authority the pilot has in roll, and possibly yaw, but the latter is not indicated to be notable in the images.
An asymmetry of some matter has occurred, but that may just be the secondary condition from a symmetric failure where there is a slight lateral change in the flow conditions of the wing. Having a severe birdstrike outboard on a wing could result in such an asymmetry, as could the lift dumper actuation while ailerons are not neutral. An engine failure on an approach, and at such a speed should not result in a flight path like this if any action is taken to mitigate, and that action is obvious and well within the authorities of the control system.

There is no FDR in this case, the CVR will give good insight into the event, the wreckage will give some forensic evidence of aircraft state for some factors but not all. The ADSB data is supportive. Beech won't have an MCAB but the flight dynamics of this aircraft are well within the normal envelope of the aircraft so replay in the FF simulator will be indicative, with a good look at the QTG derivatives to validate the replay.

The potential for interference to occur is low, it would require a hostile act that impacts both pilots, and in country that has stringent weapons restrictions. Not impossible, but it is socially and politically out of the norm. Pahang is a pretty stable region of the country, and does better than many others, the local govt is not unpopular, and any such action would have to be from within the group, and there is no obvious rationale for that. But, not impossible, just improbable.

[pattern_is_full]

Looking at the cockpit photo there are 2 `yellow-topped knobs next to the throttles..are these `engine `run/stop` controls

Looks like they are simple single-function starter-energizer buttons - without any "stop" function. The only label on them is START 1 2

Jump to about 1:40 in the video.

https://youtu.be/wZXSVzEpbgs?si=TPK4KA2hX3LK64wq&t=54

[CodyBlade]

A bit alarming no recovery action.