Close one at Frankfurt

[Timmy Tomkins]

https://avherald.com/h?article=50ae04bd&opt=0&fbclid=IwAR290C2GYomyK5x8FoLDQZ_hbf7wJ9LAqA3tMiCChAo2TKt5-NDM0ijOk0g

[DaveReidUK]

"Stalled during go-around" ???

Another incisive Avherald analysis ...

[atakacs]

"Stalled during go-around" ???

Another incisive Avherald analysis ...
Apparently so.
What is your issue with this assertion?!
​​

[DaveReidUK]

What is your issue with this assertion?!​​

Simply that there's zero evidence to support a stall.

Seems to be based on a flawed interpretation of ADS-B data. By no means the first dodgy Avherald "analysis" that has tried to use it in support of dubious conclusions.

[punkalouver]

Super-strong winds around that time not that far from the airport that day. I saw building damage. Might have been doing the Beat The Thunderstorm game.

[hans brinker]

Simply that there's zero evidence to support a stall.

Seems to be based on a flawed interpretation of ADS-B data. By no means the first dodgy Avherald "analysis" that has tried to use it in support of dubious conclusions.

60 kts groundspeed at low altitude, and an over 1000 ft loss of altitude thereafter to regain speed does not sound great. No, stall not confirmed, but I would not confidently say “0” evidence either.

[andrasz]

Simply that there's zero evidence to support a stall.

There's been an update, 50kts ground speed confirmed by DFS (official ATC) radar data.

[c52]

Looks pretty scary to me

https://www.flightglobal.com/safety/latam-767-freighter-reached-excessive-nose-up-pitch-and-stalled-during-windshear-escape/154766.article

[RatherBeFlying]

Rapid fluctuations in the 3D wind field can have nasty effects on the flight path.

QAR analysis may be able to quantify the vertical and horizontal windshears.

Shears can affect AoA

https://cimg5.ibsrv.net/gimg/pprune.org-vbulletin/1078x182/screenshot_20230831_102839_trebuchet_2_2ba97d737164c15f68592 7baa1d077cd8d1946ad.png

​​​​Bottom line: This windshear escape maneuver worked.

[physicus]

Umm... that's QAR data in the avherald article showing a minimum 78kts IAS. Fairly certain that would put a 767 into the stall regime... so, a little more than an "assertion".

And yes, the escape manoeuvre did the trick. Good work.

[fdr]

Yikes!



There is little indication of vertical vector of an outflow, there was an overshoot shear initially, seems more like a gross out of trim condition with the thrust pitch couple not being countered. Not pretty. The THS position will be of interest, the elevators position and control force applied would be telling. Not the first time, won't be the last.

[spornrad]

There is an interim report (in German) at the BFU, page 17 of the pdf.
Wind shear escape, followed by a stall recovery.
https://www.bfu-web.de/DE/Publikationen/Bulletins/2023/Bulletin2023-06.pdf;jsessionid=609548CD4D38E2308DC49D72D940D19D.live21302 ?__blob=publicationFile&v=2
My translation:
At 17:52:36 UTC, the flight crew lost visual reference to runway 25L at the decision height for the ILS approach and aborted the approach at an altitude of 684 ft AMSL. The pilot in command initiated a go-around. Shortly thereafter, a wind shear warning was issued in the cockpit. A wind shear escape maneuver was then flown, i.e. the pilot-in-command steered the aircraft into a climb and applied maximum engine thrust. At an altitude of 2,735 ft AMSL, at 17:53:19 UTC, the aircraft reached a pitch angle of +48 °, the angle of attack (AOA) at this time was +3.69 °, the airspeed was 117 kt IAS and the flaps were in the 20 ° position.
At 17:53:30 UTC, at an altitude of 2 843 ft AMSL, the stick shaker and the stall warning activated. The longitudinal pitch angle was +16° and the Angle of Attack reached +20.92°. The main landing gear was extended. The minimum indicated airspeed was 86 kt IAS and the minimum ground speed was 60 kt. Shortly thereafter, the flight crew temporarily lost control of the aircraft and descended at a rate that reached a maximum of minus 5 500 ft/min. According to the flight crew, the Stall Recovery Procedure was applied. The descent was terminated at 17:53:49 UTC at 1913 ft AMSL. The flight crew stabilized the attitude of the aircraft and the windshear warning had deactivated itself.

[atakacs]

I muss he misreading somethig
Why would you extend the landing gear in a go around?

[spornrad]

Guess it was still out 60 s after GA at 320 ft AGL. Why still not retracted?

[lederhosen]

Do not change gear or flap configuration until wind shear is no longer a factor, straight from the operations manual. Severe wind shear may also exceed the capability of the AFDS. Interesting is that the flight deck crew had a combined 31,000 hours on the 767.

[JanetFlight]

Here in English »»»
https://www.bfu-web.de/EN/Publications/InterimReports/IR2023/IR23-0502_EX_Boing_767.pdf;jsessionid=F1406FA6149BC9A68360A60C5E8 99D39.live21304?__blob=publicationFile&v=2

[Capn Bloggs]

Interesting is that the flight deck crew had a combined 31,000 hours on the 767.
​​​​​​​17,000 of that was sitting in the jumpseat...

[lederhosen]

The jumpseat is often the best place to get an overview of what is happening and call it out. Most of us have fortunately only seen stuff like this in the sim and I am sure will have experienced the stick shaker in a windshear training scenario. Clearly pitch 48 is not great and what the flight director commanded would be interesting to know as well as aircraft weight. In monday morning quarter back mode the question I would ask is whether the captain taking control during the go-around was ideal.

[jet grande]

I muss he misreading somethig
Why would you extend the landing gear in a go around?
the gear was always extended, they never retracted the gear when they initiated the GA

[punkalouver]

Clearly pitch 48 is not great and what the flight director commanded would be interesting to know as well as aircraft weight.

I remember doing a couple of windshear scenarios that were from real accidents where one is pretty much just hanging on with large pitch changes and one almost chasing the gross aircraft pitch attitude changes with elevator inputs.

The statement of "Pitch 48 is not great" got me reading the report but look at the full sentence or two: At 2,735 ft AMSL, at 1753:19 UTC, the aircraft reached a pitch angle of +48° (pitch-up), the Angle of Attack (AOA) was +3.69° at the time, airspeed 117 kt IAS and flaps were in the 20° position. At 1753:30 UTC, at 2,843 ft AMSL, the Stick Shaker and the Stall Warning were active. The pitch angle was +16° and AOA reached +20.92°.

It seems to me that while it may have only been momentary, they were in a better position at a pitch of 48 degrees than when they were at 16 degrees.

From an weather point of view, on can see that three minutes before the large pitch excursions, the weather report was SA 20/06/2023 17:50 UTC METAR EDDF 201750Z AUTO 23013G31KT 9000 0650 R25R/P2000N R25C/P2000N R25L/P2000N R18/P2000N +TSGRRA BCFG BKN///CB. And, it had been pretty much clear skies prior t this.

Therefore, one might ask, what was the view like on the weather radar and out the window in the minutes leading up to this event. This may have been easily preventable by discontinuing the approach early with a 90 degree turn.

[RatherBeFlying]

Eyeballing the QAR traces, there's a ≈2 second spike in the AoA topping at 20.92°. I suspect a vertical updraft pivoted the vanes entering the updraft. It would take ≈1 second before the entire 55m of aircraft would be completely in the updraft. The graph eventually shows AoA stabilised at -10°, which raises the question of how well the vane position in the graph is calibrated to wing AoA.
https://cimg8.ibsrv.net/gimg/pprune.org-vbulletin/800x1280/screenshot_2023_09_02_20_03_30_586_03386bb617ffce40e953eb972 62f656b9d0238b0.jpeg
​​​​​​​

[fdr]

Eyeballing the QAR traces, there's a ≈2 second spike in the AoA topping at 20.92°. I suspect a vertical updraft pivoted the vanes entering the updraft. It would take ≈1 second before the entire 55m of aircraft would be completely in the updraft. The graph eventually shows AoA stabilised at -10°, which raises the question of how well the vane position in the graph is calibrated to wing AoA.
https://cimg8.ibsrv.net/gimg/pprune.org-vbulletin/800x1280/screenshot_2023_09_02_20_03_30_586_03386bb617ffce40e953eb972 62f656b9d0238b0.jpeg



presenting time domain data on a distance X axis is somewhat unusual and can lead to odd assumptions. Normally the AOA probe has Kalman filtering for short period damping of the output for displays, however that is system dependent if the DFDAU is picking up raw or filtered data. The data also has biases that are applied to correct raw sensed angles to present AOA relative to flap geometry, and IIRC, normally that is the data that is picked up by the DFDAU, which would suggest it is filtered.

As far as a "spike" from an up draft, that presumes a... 20-30 m/sec vertical rate from some source at low levels, and what the source of such a flow is unclear. The local velocities are around 10 m/sec, and the main characteristic of a microburst is a flow field that has a downburst core, that results in outflows that translate from vertical to horizontal due to the boundary conditions of the land or sea surface. That does frequently result in a toroidal vortex structure above the gust front, which has a counter flow rotation to the downburst/outflow vectors.

Still consider the THS is likely way out of trim, the B767 could be quite entertaining if trim was not used at lighter weights on using lots of thrust change, and is not unusual in that regard, merely notable.