Aircraft down at Braidwood, NSW

[MagnumPI]

https://www.abc.net.au/news/2019-08-06/braidwood-plane-crash-pilot-killed-nerriga/11388372?WT.ac=statenews_nsw

...not good.

[0ttoL]

ATSB already have a report
https://www.atsb.gov.au/publications/investigation_reports/2019/aair/ao-2019-040/

[Squawk7700]

I used to own a Liberty. They are very simple, benign and forgiving. The newspaper witness reports say that it circled overhead and nosedived and that the pilot and a passenger flew down the night before, presumably to pick up the aircraft. Only some of them have glass cockpit which was an add-on, so it might be hard to find out exactly what happened.

[BigPapi]

Does the Liberty type have a record of nasty stall/spin characteristics, or am I misremembering?

[kaz3g]

https://www.atsb.gov.au/media/5750261/AO-2015-125%20Final.pdf

This one sounds a tad similar

[Squawk7700]

https://www.atsb.gov.au/media/5750261/AO-2015-125%20Final.pdf

This one sounds a tad similar

That report is more open ended than an empty toilet roll.

The Liberty XL2 is an FAR Part 23 certified aircraft. You’d have to do something pretty silly to come unstuck. It’s a very stable IFR training platform.

[compressor stall]

That report is more open ended than an empty toilet roll.

....and that’s being generous.

What a pointless vacuous waste of space.

The only safety message is that they communicated effectively during the incident??.What? What pray tell me is the point of that nugget of information useful for? Where’s the description of the system, the operatorks thoughts on how it was trimmed incorrectly? A pilot on same type will learn nothing, nada, zip, el zilcho from that report. Why bother ATSB, why bother.

[/rant]
Back on topic, RIP.

[Centaurus]

Regardless of the cause, if confronted with an ever increasing uncommanded extreme nose high attitude, an immediate roll up to 60 degrees angle of bank to the nearest horizon to get the nose to drop, buys you time to sort out the problem. This applies to most types of aircraft from jets to lighties. This manoeuvre should be taught at the ab-initio phase of training and can be a life saver.

[machtuk]

Regardless of the cause, if confronted with an ever increasing uncommanded extreme nose high attitude, an immediate roll up to 60 degrees angle of bank to the nearest horizon to get the nose to drop, buys you time to sort out the problem. This applies to most types of aircraft from jets to lighties. This manoeuvre should be taught at the ab-initio phase of training and can be a life saver.

That's very true 'Centy'', have always been taught that maneuverer in a jet at Sim time, few lighty drivers would have the peace of mind to roll an A/C into a steep bank to give them thinking time.
I hope they can get to the bottom of this tragic event, there has to be some purpose to the guys loss of life so maybe others can learn. RIP

[topdrop]

Did those criticising the report note this to the right of the investigation numberStatus: Activehttps://www.atsb.gov.au/Assets/Progress/progress_0.pngPhase: Evidence collection

[compressor stall]

Did those criticising the report note this to the right of the investigation numberStatus: Activehttps://www.atsb.gov.au/Assets/Progress/progress_0.pngPhase: Evidence collection
yes. I was referring to the 2015 report linked above
Aviation Occurrence Investigation AO-2015-125
Final – 28 January 2016

[Sunfish]

Sounds like the Liberty has a pitch trim problem, or else the ATSB report is BS and some other stupidity occurred.

[Squawk7700]

Sounds like the Liberty has a pitch trim problem, or else the ATSB report is BS and some other stupidity occurred.

The report doesn’t say that it has an issue, nor did the engineer that inspected it.

[Sunfish]

Does that mean then that some other stupidity occurred?

[Aerodiamond]

Yes that previous Liberty crash at Camden was my aircraft and it was put down into a paddock from off base leg at Camden. It was definitely an inadvertent lean on the electric trim. I checked the trim position straight after and it was on full nose up trim.(there was nothing wrong with the aircraft).
Reference the current accident ... we lost a bank run Aerostar year’s ago stalled tightening the turn onto final. On giving Aerostar Endorsements I get a clearance up to 8000 ft over Richmond and tell the student at 148 kts to roll into a steep turn and pull back to the stall and it will suddenly (within a second) flick upside down and go verticall and it usually then takes him several thousand feet to pull out. they will then usually say I didn’t know an aeroplane would do that no one has ever shown that to me before.
Very few instructors I speak to have ever experienced stall off a steep turn from off level flight, much less taught it.
Whenever you hear of a sudden wing drop followed by a vertical dive into the ground from a low level turn you can be certain what caused it.

[Cloudee]

On giving Aerostar Endorsements I get a clearance up to 8000 ft over Richmond and tell the student at 148 kts to roll into a steep turn and pull back to the stall and it will suddenly (within a second) flick upside down and go verticall and it usually then takes him several thousand feet to pull out. they will then usually say I didn’t know an aeroplane would do that no one has ever shown that to me before.
Wow!.........

[Centaurus]

tell the student at 148 kts to roll into a steep turn and pull back to the stall and it will suddenly (within a second) flick upside down and go vertical and it usually then takes him several thousand feet to pull outAs Sir Humphrey of Yes Minister would say with a suitably raised eyebrow "A courageous decision, Minister"

[BigPapi]

I think that's what they call a "pro-gamer move"

[BigPapi]

Stalling the aircraft and observing the behaviour of the incipient spin from level, climbing and descending turns (including from approach config) and steep turns is commonly taught in flight schools....isn't it?

[Sunfish]

Not any more.

[BigPapi]

I must be imagining it then

[KRviator]

On giving Aerostar Endorsements I get a clearance up to 8000 ft over Richmond and tell the student at 148 kts to roll into a steep turn and pull back to the stall and it will suddenly (within a second) flick upside down and go verticall and it usually then takes him several thousand feet to pull out. they will then usually say I didn’t know an aeroplane would do that no one has ever shown that to me before.I'm not sure what's braver...Doing it, or admitting to doing it.:confused:

[Squawk7700]

Not any more.

What on earth is that supposed to mean ?

[roundsounds]

What on earth is that supposed to mean ?

I think what SUNFISH is trying to say is the current standard of flight instruction relating to slow flight / stall / spinning is very poor. This is the result of inadequately skilled instructors, unsuitable aircraft types used for flight training and a poor syllabus.

[LeadSled]

I think what SUNFISH is trying to say is the current standard of flight instruction relating to slow flight / stall / spinning is very poor. This is the result of inadequately skilled instructors, unsuitable aircraft types used for flight training and a poor syllabus.
Folks,
A clear and concise summation of of the problem.
Tootle pip!!

[Sunfish]

Stalls, straight and level were taught plus one demonstration of a spin in an aerobat . That was all that was taught, I do not know if there was anything else on the PPL syllabus at the school - the one that also hated side slips. If there was, I wasn’t taught or tested on the subject.

After I got my ppl I did stalls in a turn in a certain Bellanca and later spins in an aerobatic aircraft of my own volition as I tried to extend my own safety envelope. Stalls in landing condition I first encountered during my last flight review.

Stall/spin on a base to final turn (and of course recovery) would be fun to try in a suitable aircraft at altitude. I would have done more, but my instructor in aerobatics fell off a wing and broke their leg, thus putting an end to a wonderful course of “low impact aerobatics for retirees”.

[bentleg]

Final report has issued (https://www.atsb.gov.au/media/5778936/ao-2019-040_final.pdf)

Yep, stalled when turning at low level

[Capt Fathom]

What a waste! So sad that people continue to lose their lives whilst conducting something so simple!! :(

[Clare Prop]

I think what SUNFISH is trying to say is the current standard of flight instruction relating to slow flight / stall / spinning is very poor. This is the result of inadequately skilled instructors, unsuitable aircraft types used for flight training and a poor syllabus.

No amount of training will save a pilot who decides to turn downwind at 200 feet AGL at a slow airspeed. All you can do is train people that this turn will never end well.

[Squawk7700]

No amount of training will save a pilot who decides to turn downwind at 200 feet AGL at a slow airspeed. All you can do is train people that this turn will never end well.

Upwind or downwind, does it matter?

[Zinfandel]

What a waste is how long it took the ATSB to publish the final report. The old BASI would have have got this type of report out in industry in less than 3 months.
The ATSB needs a shake up!

[Checkboard]

Upwind or downwind, does it matter?
People tend to overbank, or stomp the rudder turning downwind, due to the illusion of skid.

[machtuk]

Must be a swan job working for the ATSB! It's shameful the amount of time it takes to get a final report out in such a basic accident! Mankind never learns from their mistakes, we are good at repeating failures -(
I wonder how many of these preventable tragic events get close to becoming a statistic? Must be dozens yearly Australia wide but a link in the chain is broken just in time!

[Head..er..wind]

There was a video going around the Facebook aviation sites a while ago which explained the ‘defined minimum manoeuvring speed’ very nicely. The suggestion of having a sticker on the ASI with it clearly shown was a good one, especially for those of us who don’t fly the same aircraft type every time. For those who do, it is still a good reminder to be vigilant. Whether or not it would have helped in avoiding this crash I don’t know; can only speculate that it would have.

[john_tullamarine]

There was a video going around

A simple youtube search will come up with a number of similar videos.

(a) just do be careful taking the stories as gospel as Va is subject to a variety of OWTs and the correct story sometimes is quite different. The usual pilot story only applies for aircraft certificated to the minimum value permitted for Va. For some aircraft the OEM may well elect to design for a higher Va and therein lies a problem when the pilot fraternity typically uses an incorrect definition of what Va is about. The design standards talk about

Design maneuvering speed VA. For VA, the following applies:
(1) VA may not be less than VS https://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/0/0ac58ee778317f6085256687006d0b6e/SectionRule/0.2222!OpenElement&FieldElemFormat=gif where--
(i) VS is a computed stalling speed with flaps retracted at the design weight, normally based on the maximum airplane normal force coefficients, CNA; and
(ii) n is the limit maneuvering load factor used in design.
(2) The value of VA need not exceed the value of VC used in design.

The two important points to note are bolded in the quote. You need to know what the particular certification did before you go off doing this and that. Other bits make it clear that the pilot is responsible for making sure that any manoeuvres do not cause the limit load factor to be exceeded (often referred to as a "checked" manoeuvre). That is to say, for an aircraft designed for Va above the minimum permitted value, the pilot must not rely on protection by stalling to avoid pulling tails and/or wings off ....

(b) if you are going to run factored speed calculations to account for bank angle or steady g loads, please ensure you use CAS rather than IAS for the sums, converting IAS to CAS at the start and CAS to IAS at the finish.

(c) AFM stall speeds are based on very steady conditions (smooth air and the 1kt/sec deceleration bit). Things can get a bit off that mark if you are manoeuvring or running the speed back at a significantly faster rate.

(d) if you are going to put yourself in a stall risk situation, do so with plenty of air underneath the bird so that the hard, rocky bits don't get a look in.

[Squawk7700]

It would be great if the ASI had a line on it specific to the aircraft to show you what the “stall” speed is at MTOW on a hot day at 60 degrees of bank is, so you never go below it... problem is that this specific speed might be close to your cruise speed!

Thats where the AOA indicator could be a good thing.

[compressor stall]

At least the report is an improvement on that other one above, but if they are going to put the pretty pictures of a stall, where is the discussion about the illusions in turns?

It is, I believe, no coincidence that the stall happened at the end of the downwind turn, at low level, likely doing a constant radius as to inspect the runway strip. Everyone knows the stall, many are less familiar with low level illusions.

https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/airplane_handbook/media/08_afh_ch6.pdf

[David J Pilkington]

just do be careful taking the stories as gospel as Va is subject to a variety of OWTs and the correct story .... Design maneuvering speed VAJohn, that other post mentioned ‘defined minimum manoeuvring speed’ which is a totally different concept that I don't see being taken up by GAJSC – The General Aviation Joint Steering Committee (https://www.gajsc.org/)

[poteroo]

People tend to overbank, or stomp the rudder turning downwind, due to the illusion of skid.

Generally more so in a left turn. As the aircraft is turning out-of-wind, there is a slip illusion at low level. Rudder input is made, and the nose is forced further left. Then, as the nose drops into the left turn - they apply nose up elevator - thus the IAS falls away further. Hence the stories of IAS decreasing from up to downwind. This combination of inputs ensures the arrival at stall happens much faster than they ever thought possible. Even from 500 agl, recovery is usually impossible.

[roundsounds]

People tend to overbank, or stomp the rudder turning downwind, due to the illusion of skid.
the illusion is actually a slip, resulting in a skid.

[Checkboard]

Either way.

[Styx75]

the illusion is actually a slip, resulting in a skid.
Is it even an illusion though? I mean what you see is what is actually happening. Trying to stop it happening is where the problem starts...

[Bodie1]

Yes, it's an illusion. Read the definition of illusion.

[compressor stall]

Read the ATSB report. The dangers and illusions of low level flight and associated illusions that likely lead to LOC-I are covered in detail.

oh, wait, :ugh:🦄

[Bodie1]

Have read the ATSB report and have studied Human Factors, Threat and Error Management, discussed illusions, read lots about that as well. The nature of this accident can't 100% 'rule in' illusion causing it, it can't 100% rule it out either. But it's real.

[john_tullamarine]

that other post mentioned ‘defined minimum manoeuvring speed’ which is a totally different concept

Indeed, Dave. However, when I ran a search for DMMS (a term which I had never encountered before) the hit provided both Va and Vs related considerations. I get the impression that DMMS is a term coined by the lightie fraternity in the US ? The DMMS, being a simple load factor increment to Vs still is a bit silly without any margins being applied. I note that a similar idea is used on heavies for manoeuvring margins, but with a sensible stall pad.

[Head..er..wind]

m.youtube.com/watch?v=m_tKShlf_gU

[compressor stall]

Bodie - I don't need convincing that it's real. Read my 2nd post above.

In this report, the ATSB has completely ignored the issues and illusions in turns at low level. Instead they've just given a vacuous paragraph saying that training is involved for low level flights and shouldn't otherwise be done and simply given an aeronautical outline of what a stall is under the "Additional Information" Chapter.

Now there is no 100% proof that any of the low levels illusions caught out this pilot. That can, sadly for obvious reasons, never be proven. But look at what he was doing and where he stalled. If it walks like a duck, and talks like a duck it should be at least discussed as a possible causal factor, not just swept under the carpet to ignore. And look at the temporary airspeed decrease during the turn from downwind to upwind. More evidence of being affected by the illusions in the turn.

Further to my FAA link above - have a good read of a similar accident from the Canadian TSB in nil wind. Look at the issues in 1.18. https://www.tsb.gc.ca/eng/rapports-reports/aviation/2015/a15q0120/a15q0120.htm Compare and contrast the thoroughness of the report to the ATSB one.

Transport Canada devote 4 pages of its Flight Instructor Manual to the illusions of low level flight, including diagrams and lesson plans. It's the lesson before Prec Searches.
CASA's FIM, by contrast, has 1 paragraph on briefing the student on optical illusions in turns during a precautionary search and landing.

Finally, has anyone worked out how the additional risk in the accident was the overdue oil change?

[Lead Balloon]

[H]as anyone worked out how the additional risk in the accident was the overdue oil change?The stall speed of a piston-engined aircraft increases by 1 knot for each hour the engine is overdue for an oil change. Surely you learnt that in BAK?

[Pinky the pilot]

The stall speed of a piston-engined aircraft increases by 1 knot for each hour the engine is overdue for an oil change

But isn't that only applicable if the thronomister sender unit is unservicable?:confused:

[Squawk7700]

At least the pilot doesn’t appear to have been show-boating. Just a fun day out with mates that ended badly. If he was showing off, it would have been closer to 50 knots faster. Sad considering a fairly high number of hours on type and a lot of recent hours.

[machtuk]

Speed has nothing to do with 'showboating' It's the attitude of the driver and their lack of knowledge.

[Squawk7700]

My point being, it sounds like his mate had landed prior, phoned him up and cautiously said not to land. Pilot continues on and circles overhead waiting for his mate to take off again. We’ve all done that before haven’t we? Continues to fly overhead, probably looking at the ground with only 15-20 degrees angle of bank.

Lack of some concentration and the speed gets a bit low and down he goes down in the turn.

He wasn’t hitting a power line at the back of the pub at Bourke doing 140 knots at 30 feet....

I used to own a Libety XL2, same aircraft exactly and it runs a very thin wing profile that takes a solid amount of airspeed to get it flying. When it lets go, it doesn’t mess about and it drops hard onto the runway at the stall.

[Checkboard]

It's the lesson before Prec Searches.
CASA's FIM, by contrast, has 1 paragraph on briefing the student on optical illusions in turns during a precautionary search and landing.
Really? When I was instructing back in 1988, there was a specific low flying illusion lesson before prec search.

[Pinky the pilot]

there was a specific low flying illusion lesson before prec search.

Likewise back in '82 when I started my Flying training.

And when I commenced the training required for the low level endorsement to carry out bird scaring ops at the end of '90, the lesson quoted above was really hammered into me! (Thanks DD, if you read this.)

[Bodie1]

compressor stall, so we're in violent agreement then?

[Bodie1]

When I was instructing back in 1988, there was a specific low flying illusion lesson before prec search.

I seriously doubt that any Part 61 instructor rating these days pays anything but cursory attention to the illusions that can occur.

I still have the notes from my original rating, covered extensively and part of a flight lesson.

[compressor stall]

compressor stall, so we're in violent agreement then?
Were we not?