CL-415 crash firefighting in Italy, 27/10/22

[treadigraph]

On Sicily... very sad.

https://aviation-safety.net/database/record.php?id=20221027-0

https://youtu.be/Tn-u1fBV7rY

[Pilot DAR]

That's hard to watch. My thoughts take me to a tired crew who feel rushed to get an important job done, and just miss the physics of the situation for a moment. Sometimes you cannot fulfill the need as much as you wish you could. Set up for a second try, rather than risking too much trying to get it done on the first run.

[Flying Binghi]

Part one…

https://m.youtube.com/watch?v=rcJW6hRPc4I

[FullOppositeRudder]

Very much agree with Pilot DAR's observation above. It was all a bit rushed.

It's hard to be certain, but I also speculate that what wind there was, is coming towards the vantage points in both videos - ie from behind the ridge and over the top If that were, so then the "clutching hand effect" on the lee side of any ridge could be in play here and could have contributed to the tragic outcome. So sad.

Whenever I watch our blokes head off towards the smoke in the hills with three tonnes of product which we've just loaded, I whisper a little prayer for their safety ...

[avionimc]

Blancolirio’s take:
https://youtu.be/M73lyUmjL7s

[ShyTorque]

Sad to see. It seems to me that the pilot was caught out by the classic “apparent airspeed” phenomena. Flying downwind at very low level gives a false visual impression of aircraft IAS if you’re only looking outside, rather than monitoring the ASI.

Low IAS, gusty wind, a heavily laden aircraft, AOB increasing to avoid terrain, all leading to a stall/incipient spin LOC.

Easy to say in hindsight, but flying the manoeuvre in the opposite direction would have prevented this because any gusts would tend to increase the IAS, rather than reduce it.

[Pip_Pip]

Aerial firefighting operations carry a necessarily elevated degree of risk, but this one looks especially perilous to a non-professional like me. Slow, steeply banked and releasing the water mid-turn onto the slope of a hill - is that really the manoeuvre that they set out to attempt?

Either way, the courage required boggles my mind. So sad to see it go wrong.

I'd like to learn something about the timing and impact of the water release. Was the outcome already inevitable before the moment of release, or did the release itself and the resulting change in characteristics contribute to the loss of control, with no time to react? Alternatively, as suggested by one of the videos, was it an 'emergency dump' in a last ditch attempt to recover the situation?

Apologies if this question seems dumb or insensitive. It's not intended to be either.

[fdr]

Sad to see. It seems to me that the pilot was caught out by the classic “apparent airspeed” phenomena. Flying downwind at very low level gives a false visual impression of aircraft IAS if you’re only looking outside, rather than monitoring the ASI.

Low IAS, gusty wind, a heavily laden aircraft, AOB increasing to avoid terrain, all leading to a stall/incipient spin LOC.

Easy to say in hindsight, but flying the manoeuvre in the opposite direction would have prevented this because any gusts would tend to increase the IAS, rather than reduce it.


maybe, it may also be that the crew had a false horizon and ended up pulling too high a g loading leading to a badness. Seems he was actually into wind up until the nose drop and increasing bank which is characteristic of a stall in the turn, yet heading into wind. The different vantage points show the aircraft has departed controlled flight and rolled beyond vertical and the nose has sliced down rapidly, it has commenced an incipient spin. In dynamic manoeuvre like that close to the ground, unless the pilot had a HMD he wouldn't get much reference from the head down displays, and even a HUD would not be where he would be looking, he (or she) would be looking out above and right of the nose. There are means to add simple HMD for the pilots, which would at least keep an awareness of where they are running into marginal conditions of flight. We just saw a V-22 have a bad day mid year for pulling in a steep turn that exceeded the capability of the aircraft to maintain level flight or anything close to that. This is similar, in part, the flight path places the aircraft in a position where the crew approach or exceed the preformance capability of the aircraft, close to the ground. AOA awareness along is nice, but where the horizon is difficult to discern, and the instruments are not in full view of the pilot driving, then the problem comes down to attitude awareness first, IMHO.

These guys are doing a demanding task, anything that makes their life easier would be a good thing, if not a HMD, then even an aural alert of the bank angle as it gets to much higher tactical manoeuvre levels would give them a heads up that there is a performance problem under way.

[markkal]

I know most of these pilots personally, and in Italy Canadair firefighthing is led by a mix of military and civilian pilots. All my condoleances to the crew. All captains are highly experienced and fully capable and take great risks operating so close to the ground.
They often do several missions a day and it can and does happen that they have few options should anything go wrong.
I do not wish to judge or come to any conclusions, and there will be an inquiry for this.
There has been extensive video footage from different vantage points which in hindsight may allow to make a few considerations.
As a mountain rated pilot, there are a few things that strike me, but again I do not have the full picture of the orography the crew had in this accident, i.e. the view from the cockpit nor was I exposed to the startle factor occuring in such situations.:

The very high bank angle during the final turn and positionning, well in excess of 60 AOB, close 80 AOB. Increasing apparent weight, and decrease of IAS on an aircraft already heavy laden with fuel and water.
Then the scoop and water release during the turn on the opposite side of the fire;
The crew at this point most likely realised the degraded situation and had to get rid of the excessive weight.
But they were banking and went into a dynamic stall ,with the very much increased dynamic stall stall speed; Unrecoverable. There seems to be a ridge ahead which may have prevented the levelling off and escape maneuver, difficult to judge.

The captain was an highly experienced previous fighter pilot. But many years ago he had a crash in a Siai 208 in which his crew member died.
The inquiry concluded in reckless flying and he was charged; The air force owner of the aircraft sued him for financial compensation.
Charges were subsequently dropped and he was reinstated.

[Flying Binghi]

Have a look-see at the beginning of the part one video again. Note the into sun glare. Further along the flight path note the turn of the aircraft reference the smoke plume it were apparently targeting and consider the direction of the sun glare at that time.

[markkal]

Another perspective:

https://www.youtube.com/watch?v=Tn-u1fBV7rY

Looks like link does not show, in this case justo google you'll find it

[ShyTorque]

Note to Moderator: I've just changed from iPad to desktop PC. I can no longer see the above links to videos, although I've never had an issue before today. Anything been changed?

[punkalouver]

Aerial firefighting operations carry a necessarily elevated degree of risk, but this one looks especially perilous to a non-professional like me. Slow, steeply banked and releasing the water mid-turn onto the slope of a hill - is that really the manoeuvre that they set out to attempt?

Either way, the courage required boggles my mind. So sad to see it go wrong.

I'd like to learn something about the timing and impact of the water release. Was the outcome already inevitable before the moment of release, or did the release itself and the resulting change in characteristics contribute to the loss of control, with no time to react? Alternatively, as suggested by one of the videos, was it an 'emergency dump' in a last ditch attempt to recover the situation?

Apologies if this question seems dumb or insensitive. It's not intended to be either.

My thought was whether it would have been helpful to emergency dump the water earlier.

These things can get forgotten when focus is intense.

[ShyTorque]

My thought was whether it would have been helpful to emergency dump the water earlier.

These things can get forgotten when focus is intense.

They might have got away with the manoeuvre if the aircraft had been far lighter but bearing in mind that the LOC happened so quickly, it's a moot point. Sadly, the aircraft was probably in a position where recovery was almost impossible.

[sycamore]

Think it all went wrong turning inside the ridge-line,rather than extending `Downwind` and approaching over the ridge into the valley,wings-level to drop.A lot of drops are usually run by a `spotter`/bird-dog` who can direct the tanker to fly/follow for the best route to drop.

Was this the first drop on this fire,or had other aircraft been previously...?

[Saab Dastard]

Note to Moderator: I've just changed from iPad to desktop PC. I can no longer see the above links to videos, although I've never had an issue before today. Anything been changed?
Nope. This is a common problem, although no solution in sight. Sometimes you can see the link(s) when you Reply (without posting).

[Pip_Pip]

Thank you to all who posted since my questions at #7, for helping me to interpret what I'm seeing. It's a tight rope to walk, offering insight without a full view of the facts and also avoiding judgment.

[ehwatezedoing]

Sad to see. It seems to me that the pilot was caught out by the classic “apparent airspeed” phenomena. Flying downwind at very low level gives a false visual impression of aircraft IAS if you’re only looking outside, rather than monitoring the ASI.

No idea about the Italian but for the Ontario Ministery’s CL-415 it is SOP to dump your load downwind (So it will cover more ground)

This said, I totally agree with Blancolirio’s take on YouTube posted by avionimc above) This was a totally unnecessary high risk manœuvre, trees can grow again and houses be rebuilt.

I would add that the Croatian CL-415’s unit should take note of that particular crash as they seems pretty fervent of high risks manœuvres with Zero exit doors in case of a problem.

[DaveReidUK]

Nope. This is a common problem, although no solution in sight. Sometimes you can see the link(s) when you Reply (without posting).

This should hopefully work, regardless of browser:

Tn-u1fBV7rY

[ShyTorque]

Nope. This is a common problem, although no solution in sight. Sometimes you can see the link(s) when you Reply (without posting).

Back on the iPad and I can see them again.

[FullOppositeRudder]

Surely pilot fatigue leading to errors in judgement both in the planning and execution of the task has to be a factor here. How else to explain what we see? Blancolirio’s analysis is valid, but how did they ever get into that predicament when it seemed to have been not really necessary for protection of either life or assets anyway? Perhaps the inquiry will reveal whether they were operating under a request to drop at that spot, or operating under their own initiative ....

A further point if I may.... Without having even the faintest idea of how aerial fighting is 'managed' outside of my own involvement in one of the 'down under' regions, it used to be (and possibly still is) a requirement here for lots of hours (thousands I seem to recall) in aerial ag operations before one could strap on an aircraft loaded with fire fighting product and head off towards the smoke on the horizon. The reasons are / were that you need a lot of experience operating a loaded aircraft close to the ground in a wide variety of situations and terrain in relatively benign conditions before entering into the additional unknowns of variable visibility, extreme turbulence, heat, and often windy conditions in totally foreign terrain. I don't know how many hours the PIC had in low level fire operations, but somehow he was seduced into a manoeuvre which was destined to end badly.

Finally, does anyone know the crew configuration for these ops? - two pilots or pilot and observer / mission director? If only one of the crew was PF, and was flying from the LH seat, it seems probable that the precise location of the target for the drop would have been partially or totally obscured for much of the approach. Perhaps that could explain the sudden increase in bank once it actually became visible - too much - too late as it turned out.

PS Incidentally, I run a desktop Windows 10 box at this desk and all links have been present for the duration of the thread - confirmed on Firefox, Edge, Chrome and Vivaldi browsers - strange.

[RatherBeFlying]

Analysis of my recorder data produced this chart of wind velocities. The y-axis wind component could not be determined from the available data.

From the chart we can infer a vortex followed by a downburst.

I was very lucky.
https://cimg5.ibsrv.net/gimg/pprune.org-vbulletin/1051x859/screenshot_20221031_105810_trebuchet_2_02d727f7ed19400495337 f716d8ff0b581811f51.png

[Flying Binghi]

Analysis of my recorder data produced this chart of wind velocities. The y-axis wind component could not be determined from the available data.

From the chart we can infer a vortex followed by a downburst.



A bit more background to what we are looking at please..;)

[fdr]

Analysis of my recorder data produced this chart of wind velocities. The y-axis wind component could not be determined from the available data.

From the chart we can infer a vortex followed by a downburst.

I was very lucky.
https://cimg5.ibsrv.net/gimg/pprune.org-vbulletin/1051x859/screenshot_20221031_105810_trebuchet_2_02d727f7ed19400495337 f716d8ff0b581811f51.png


The terrain the aircraft was flying over and the wind do not glaringly suggest a rotor entry. If the aircraft was on the less side of a ridge that had a fairly defined ridge line, and a strong wing was present, particularly if the wind flow is oblique to the terrain, then a rotor could be an interesting option, but, then the attitude of an aircraft entering a rotor with an open loop control is quite predictable. The images show enough resolution to not suggest that the aircraft entered into a rotor. Always a consideration, was an item that came up with UAL 585...

The trees in some of the photos suggest that the camera is not level with the horizon, so the actual bank angle is open to more analysis by the investigators, but it was steep, looks close to 90 but is probably at least 70.... and that adds a pretty high AOA requirement for level flight and more for a pull out. The roll into the run has a high bank angle, but a descending flight path initially, so AOA is modest, then the bank is increased and a pull out is conducted, and AOA is going to spike, about the time that the aircraft does a rapid right roll, and the nose slices downwards, which is characteristic of an incipient spin entry.

I would remain concerned with the loss of awareness of the horizon by the crew in the path that they flew, they may have had little awareness of how close to a bad day their banked pullout was going to take them. The problem with experience is that it increases our confidence that we are on top of the risks that exist, and so the SOPS such as bank limits, crew crosschecking etc are not necessary, (didn't hurt us before, etc) Nothing in LL ops around fires is trivial, fixed or rotary. The guys doing it are darned good, and it is still dangerous, basics still apply every time.

[Flying Binghi]

…

The trees in some of the photos suggest that the camera is not level with the horizon, so the actual bank angle is open to more analysis by the investigators, but it was steep, looks close to 90 but is probably at least 70...
​​ …


Agree. The power poles in video #2 clearly show the perceived tilt of the camera reference the aircraft. Is the perceived tilt due to camera tilt or looking down/up to the aircraft - don’t know.

[RatherBeFlying]

Airflow over varied terrain can produce up and down flows as well as vortices with axes anywhere from vertical to horizontal.

We can't see what the air is doing downwind of obstacles, but it's instructive to observe water flow over rapids. Lots of vortices and waves.

​​​​​​A vortex with a horizontal axis can produce a shear of twice the wind aloft.

[markkal]

A follow up on my comment left above. There are plenty of videos, and data to help the inquiry come to conclusions, this will take time. The final report will be published, but not before 2 years. There have also been reports that the aircraft hit some power lines. So better not speculate here.

However there are rumors, within the firefighters community and an old Tornado pilot who was flying decades ago with the captain involved, that the captain may , I say may, have been trapped by it's own bravado.

While certainly a very skilled pilot, he had a reputation of having the the wrong behaviour and mindset.
He was involved in a crash years ago with a Siai 208 airforce trainer in which a young navigator died and he survived. And the inquiry concluded in reckless flying.
There are suspicions that he was lacking the discipline necessary to stay safe. So one cannot dismiss an complacent and over confident attitude.
This is a risking activity, which being also repetitive does not allow for any deviance. And "normalisation of deviance" in this framework will eventuall bite.

There is an article about the crash in the regional sicilian issue newspaper "La repubblica" titled..."The hero and the reckless".........
https://palermo.repubblica.it/cronaca/2022/10/28/news/canadair_precipitato_incidente_etna_catania-372087352/

[9 lives]

I opine that the final report will contain a statement which more or less says: "Failure to maintain flying speed". It's up to we pilots to anticipate conditions in which variable winds and other topographic factors could affect the flight, and make allowance for them. This pilot, for whatever reason, cut a corner too tight. The task could have been competed with a very different and more safe approach - there was room.

[avionimc]

"La repubblica" titled..."The hero and the reckless".........
https://palermo.repubblica.it/cronaca/2022/10/28/news/canadair_precipitato_incidente_etna_catania-372087352/
"l'eroe e il temerario"

Even though reckless is indeed one of the words of 14 CFR 91.13 - Careless or reckless operation.
A finding of recklessness (e.g., a willful disregard of other people's safety) carries a considerably greater burden of proof than does a finding of carelessness.

The word temerario in this non-aviation newspaper article would probably be better translated with fearless, daring or even courageous.

https://www.ecfr.gov/current/title-14/chapter-I/subchapter-F/part-91/subpart-A/section-91.13

[DaveReidUK]

The word temerario in this non-aviation newspaper article would probably be better translated with fearless, daring or even courageous.

I think in this instance "reckless" is closer to the newspaper's intended meaning. It appears to be a reference to one of the pilots having previously been jailed after being convicted of culpable homicide following a fatal aviation accident in 1997.

Scampò alla tragedia di Monte Lupone, pilota muore 25 anni dopo in un incidente aereo (ilmessaggero.it) (https://www.ilmessaggero.it/latina/morto_in_un_incidente_aereo_25_anni_dopo_monte_lupone-7020960.html)

[markkal]

I think in this instance "reckless" is closer to the newspaper's intended meaning. It appears to be a reference to one of the pilots having previously been jailed after being convicted of culpable homicide following a fatal aviation accident in 1997.

Scampò alla tragedia di Monte Lupone, pilota muore 25 anni dopo in un incidente aereo (ilmessaggero.it) (https://www.ilmessaggero.it/latina/morto_in_un_incidente_aereo_25_anni_dopo_monte_lupone-7020960.html)

From what I know, he was charged, but did not serve time in jail. Anyway let's wait for the final conclusions of the inquiry. There may well be other issues which we don't know at this time.

[avionimc]

Exactly.
And, charges for the 1997 crash were subsequently dropped and he was reinstated, as mentioned by markkal earlier.

[Flying Binghi]

A follow up on my comment left above. There are plenty of videos, and data to help the inquiry come to conclusions, this will take time. The final report will be published, but not before 2 years. There have also been reports that the aircraft hit some power lines. So better not speculate here.

However there are rumors, within the firefighters community and an old Tornado pilot who was flying decades ago with the captain involved, that the captain may , I say may, have been trapped by it's own bravado.

While certainly a very skilled pilot, he had a reputation of having the the wrong behaviour and mindset.
He was involved in a crash years ago with a Siai 208 airforce trainer in which a young navigator died and he survived. And the inquiry concluded in reckless flying.
There are suspicions that he was lacking the discipline necessary to stay safe. So one cannot dismiss an complacent and over confident attitude.
This is a risking activity, which being also repetitive does not allow for any deviance. And "normalisation of deviance" in this framework will eventuall bite.

There is an article about the crash in the regional sicilian issue newspaper "La repubblica" titled..."The hero and the reckless".........
https://palermo.repubblica.it/cronaca/2022/10/28/news/canadair_precipitato_incidente_etna_catania-372087352/


Hmmm… I think some are trying to hang two innocent pilots. For starters, which one were actually flying at the time of the prang ?

From the limited info presented to this thread so far I can see no deliberately ‘dangerous flying’ as such from the pilot. There are some who think flying aircraft just above the tree tops, in hill country, in gusty and low vis conditions is a dangerous activity - to the fire bomber crews it is just another day at work.

I suspect the prang were merely a simple mistake that could have happened to any crew.

Looking at the limited information available on the two videos in this thread we can ballpark wind direction and visibility and what the sight picture of the pilots might have been. Wind direction indications for the valley at the time of the prang can be found at the end of video #1. Sun glare effect can be found at the beginning of video #1.

We don’t know the actual location of the fire the pilots were targeting. The smoke seen in the video could be well down wind of the actual fire.

Reference the aircraft turning right starting at the beginning of the videos you can note the ‘flow’ of the terrain leading up to where the aircraft crashed. You can see a valley just behind the water drop and after that what appears to be a protruding ridge that caused the aircraft to veer away from and stall. From the limited video info there appears to be no houses or power poles on that protruding ridge. Houses are important for getting that ballpark distance ‘feel’ in low vis. i.e. house big = close.

The lead in flight track around the hill top ridge line seemed prudent to me considering the apparent wind direction. The track would have kept the aircraft in the relatively ‘clean’ updraft wind coming up the valley whilst positioning the aircraft for a down valley water drop - except the protruding ridge got in the way. How did they not see it?

Noting the through smoke sun glare effect at the beginning of video #1 I would guess the pilots would have had a similar degraded view looking towards their flight path. Looking through smoke degrades depth perception. Looking through smoke at a dull green-brown back ground of hills with sun glare gives a pilot an extremely limited depth perception - unless, there be a distance reference of a house for example.

Whilst depth perception issues are just another thing in the day to day of air fire fighting I suspect that little protrubance of a near invisible, to the crew, green-brown protruding ridge were just not noted by the crew until the last moment. A simple innocent mistake.

[DaveReidUK]

Exactly.
And, charges for the 1997 crash were subsequently dropped and he was reinstated, as mentioned by markkal earlier.

Thanks for the update - I stand corrected re the prison sentence.

That said, the "reckless" reference appears to be a direct quote from the sentencing remarks of the Tribunale Militare where he was described as a "pilota avvezzo a condotte spericolate". It's not clear whether that was before or after he had also been disciplined for instances of unauthorised low flying while piloting AMX's.

[markkal]

Critics involve the captain. Not a single reproach to the co-pilot. Who was praised and respected among the group. During operations it is always the captain flying according to what I've been told by crews.

[Flying Binghi]

Critics involve the captain. Not a single reproach to the co-pilot. Who was praised and respected among the group. During operations it is always the captain flying according to what I've been told by crews.

The co-pilot is not just sitting there sight-seeing. It is a two crew operation.

[markkal]

The co-pilot is not just sitting there sight-seeing. It is a two crew operation.

You'd be surprised....Firefighting and scoops are handled by captains

[FullOppositeRudder]

I keep on thinking back to the C130 accident in the Snowy Mountains NSW in January 2020 with the loss of all on board. Despite the different aircraft involved, there are parallels in that both crew were undertaking a fire bombing task which went wrong and both aircraft and the brave crew were lost. These were dedicated aviators at the top of their game and yet the circumstances caught them out. Much of the science of aviation safety relies on us learning from other peoples mistakes and making changes in operational procedures and other factors to avoid a repetition of previous errors. I am sure that will happen in this instance also.

In the meantime, the report of the C130 tragedy may be of interest: https://www.atsb.gov.au/publications/investigation_reports/2020/aair/ao-2020-007/

[markkal]

I keep on thinking back to the C130 accident in the Snowy Mountains NSW in January 2020 with the loss of all on board. Despite the different aircraft involved, there are parallels in that both crew were undertaking a fire bombing task which went wrong and both aircraft and the brave crew were lost. These were dedicated aviators at the top of their game and yet the circumstances caught them out. Much of the science of aviation safety relies on us learning from other peoples mistakes and making changes in operational procedures and other factors to avoid a repetition of previous errors. I am sure that will happen in this instance also.

In the meantime, the report of the C130 tragedy may be of interest: https://www.atsb.gov.au/publications/investigation_reports/2020/aair/ao-2020-007/

Aerial firefighting is a risky activity which allows for nearly zero error margin.

[Flying Binghi]

You'd be surprised....Firefighting and scoops are handled by captains

I’m not blaming either pilot as such. That’s for the accident investigators. I offered up a scenario of a simple mistake. Others in the thread have offered up plausible considerations reference rotor turbulence.

It will be interesting to see if the accident investigators fly the track of the crash aircraft (in a helicopter) to get a pilots eye view of the lead in to the prang.

[markkal]

Absolutely, let's wait for the investigation report, as there are many variables to consider, and we cannot get the full picture at this point. However the captain troubled past sparked reactions which have been relayed by the press.

[Flying Binghi]

Absolutely, let's wait for the investigation report, as there are many variables to consider, and we cannot get the full picture at this point. However the captain troubled past sparked reactions which have been relayed by the press.

The press…:yuk:

[FullOppositeRudder]

Quite an interesting video on the Canadair itself, limited significantly (for me) by my total inability to understand the beautiful Italian language - and one other distraction :E. However it was most educational even then, and a fascinating comparison / contrast with our local ops utilising the AT-802.

https://www.youtube.com/watch?v=DclvUrMz8TY

[RatherBeFlying]

Thanks to FOR for linking to the ATSB report which made good use of ADS-B and recorder data to estimate airspeed loss. But AoA changes were not included.

Frost’s 1983 paper, Flight in Low-Level Wind Shear commissioned by NASA supplies:

https://cimg1.ibsrv.net/gimg/pprune.org-vbulletin/1374x332/screenshot_20221103_203840_trebuchet_2_0fdaec00c223e349a87d6 2f8c746daaa362abf79.png

Where: q is the pitch (rate?), the elevated dots are differential over time (equivalent to dt), W is wind in the x and z axes, w indicates wind frame, E earth frame.

What appears to many as an accelerated stall from pilot input may well be a result of gusts. ADS-B and recorder data with video analysis may give a better picture of what happened.

[Liffy 1M]

Quite an interesting video on the Canadair itself, limited significantly (for me) by my total inability to understand the beautiful Italian language - and one other distraction :E. However it was most educational even then, and a fascinating comparison / contrast with our local ops utilising the AT-802.

https://www.youtube.com/watch?v=DclvUrMz8TY
If watching on Youtube you can set for subtitles with auto-translation to English which, while not perfect, gives a reasonable idea of what's being said.

[avionimc]

Great video FullOppositeRudder! Thanks.
comparison / contrast with our local ops utilising the AT-802
Indeed, a SEAT or a helicopter with a bucket would have been more appropriate for a drop in this terrain (not sure if these assets are available in Italy though).

[fdr]

Thanks to FOR for linking to the ATSB report which made good use of ADS-B and recorder data to estimate airspeed loss. But AoA changes were not included.

Frost’s 1983 paper, Flight in Low-Level Wind Shear commissioned by NASA supplies:

https://cimg1.ibsrv.net/gimg/pprune.org-vbulletin/1374x332/screenshot_20221103_203840_trebuchet_2_0fdaec00c223e349a87d6 2f8c746daaa362abf79.png

Where: q is the pitch (rate?), the elevated dots are differential over time (equivalent to dt), W is wind in the x and z axes, w indicates wind frame, E earth frame.

What appears to many as an accelerated stall from pilot input may well be a result of gusts. ADS-B and recorder data with video analysis may give a better picture of what happened.


Frost uses the term "q" for pitch rate. Separately, alpha.dot is more or less proportional to pitch rate, "q'. The next step from that formula is to look at the pitch rate derivative, Cmq, and that sets up a fair idea of how much fun the plane will be to fly,
p, q, r are body-axis angular rates, (usually rad/s)

https://cimg4.ibsrv.net/gimg/pprune.org-vbulletin/170x56/screen_shot_2022_11_04_at_8_08_26_pm_f7704d7431465a9b530606b a70ca25c792f049e2.png

where at is the tailplane lift curve, VsubH is the horizontal tail volume, and the last term is the moment arm from the center of mass and the MAC of the tail. That is a conventional statement, using the center of mass, which is arguably a nice convention but not strictly true, but the values reflect the same outcome.


FWIW, Frost's algorithms are seen in a simplified form in the reactive wind shear algorithm. Back when that came out, the algorithm triggered on loss of performance, while there was credible modelling from Fujita that would give a good basis for having the trigger earlier on the basis of increasing performance from the steady state. IIRC, EGPWS made the change to the algorithm moot. In some cases, it would have given around 10 seconds earlier WS warning, even as a reactive system. There goes the neighbourhood. :}

[avionimc]

Do they use Air Attack airplanes (also as a Lead Airplane) with a Fire Coordinator (ATGS) in Italy?

https://www.nifc.gov/resources/aircraft/tactical-aircraft

[FullOppositeRudder]

Thankyou Liffy_1M - regarding the youtube translate feature - I had no idea that was on offer. It certainly was of assistance in working out what she was conveying so well but in her own language. As you say, far from a perfect translation but it helped.

I learn something from PPRuNe most days - sometimes even in the non aviation area. Thank you again:D