Mallard Down in Perth
Yes, and the effect is gross weight dependent. Another hole in the cheese.
Aside from the aerodynamics, was the Mallard sequence in the display planned, documented and reviewed by a Display Committee ? A circuit, landing and takeoff sounds a simple thing compared to other's formations and aeros in the box, but in hindsight it would seem not. Were his two previous descents below 500' attempts to land or just part of the show, and if the former was there a Coordinator on the ground with a radio to tell him to go home when it became obvious (on the last downwind leg) that things were getting out of hand in terms of turn radius v. box boundary ?
Things like that are ultimately going to be ATSB questions relating to CASA oversight of air displays.
Aside from the aerodynamics, was the Mallard sequence in the display planned, documented and reviewed by a Display Committee ? A circuit, landing and takeoff sounds a simple thing compared to other's formations and aeros in the box, but in hindsight it would seem not. Were his two previous descents below 500' attempts to land or just part of the show, and if the former was there a Coordinator on the ground with a radio to tell him to go home when it became obvious (on the last downwind leg) that things were getting out of hand in terms of turn radius v. box boundary ?
Things like that are ultimately going to be ATSB questions relating to CASA oversight of air displays.
Avoid imitations
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That's the obvious answer, if you can be certain that the aircraft was actually stalled. However, I was rather thinking about stall warning signs, such as buffeting, and the correct actions to be taken. I don't think there can be many types, if any, where use of aileron can help recover the situation.
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"Turning 'downwind' in a constant airmass with a fixed angle of bank is going to have the same performance impact as turning with the same angle of bank in a non-moving airmass"
Please consider this as I have witnessed this many times. Ie holding in very strong winds.
I reduced angle of bank to prevent excessive IAS loss.
Ground speed heading west is IAS minus wind. ( the Perth Westerly, sea breeze can be quite strong in high temperature days)
Ground speed heading east is IAS plus wind.
Inertia must be increased quickly therefore IAS will drop until ground speed equals IAS plus wind.
Sometimes this requires over a 50 knot increase in a short time.
Please consider this as I have witnessed this many times. Ie holding in very strong winds.
I reduced angle of bank to prevent excessive IAS loss.
Ground speed heading west is IAS minus wind. ( the Perth Westerly, sea breeze can be quite strong in high temperature days)
Ground speed heading east is IAS plus wind.
Inertia must be increased quickly therefore IAS will drop until ground speed equals IAS plus wind.
Sometimes this requires over a 50 knot increase in a short time.
This sounds suspiciously like you're heading into the oh-so-classic argument I've seen posted on various flying forums over the decades that goes something like "Well if you want to avoid a stall always make sure you turn into the wind, not away from it..."
This thinking that there's a difference in aircraft performance turning upwind versus downwind and that the aircraft's momentum needs to be taken into account when considering turning upwind or downwind is one of those fallacies that just keeps popping up again and again and I've seen some pilots swear black and blue that it's definitely something to be mindful of and keep in your tool bag of tricks.
As the first poster said "Turning 'downwind' in a constant airmass with a fixed angle of bank is going to have the same performance impact as turning with the same angle of bank in a non-moving airmass". That is absolutely factual. All that differs between flying in a constant moving airmass (i.e. wind) versus flying in completely still conditions is the aircraft's track across the ground. Momentum has nothing to do with the aircraft's airspeed and performance and (in a "constant moving airmass" i.e. we're not talking about gusts, wind shear or turbulence) a turn downwind is absolutely equal to a turn upwind and involves no difference to airspeed.
Accident's of this nature can often be attributed in part to the actions of the pilot in regards to their perception of movement over the terrain, especially at such a low level. In a turn from any direction whilst travelling downwind the aircraft is going to appear to be not changing its course rapidly enough (in reference to its position over the ground) and this is often when a pilot starts pulling excessive levels of bank to correct and attempt to achieve the desired turn radius. This accident is probably very similar to many one reads about where a pilot's turning from base to final on approach with a strong cross-wind that's causing them to overshoot during the turn. There have probably been hundreds, if not thousands of these accidents since flying started. Pilot overshoots turn, and banks further and further trying to stop the overshoot then, with their airspeed already low for the approach and their angle of attack high, they stall and spin in.
What's particularly disheartening is that it's clear from the many photographs and videos no flaps were deployed. On a 40º+ day, which (as a previous poster has noted) would have involved a density altitude in the thousands, to be flying low and slow in a strong wind (in a relatively large aircraft for the "box" it needed to remain in) and to be attempting to do that without the extra lift flaps would have provided does seem to be asking for trouble.
My condolences to the friends and families of the pilot and his passenger too. Having spent some years operating a floating hull aircraft myself and having spent a lot of time flying low and slow down close to the water, I know just how easily this type of accident can happen. "But for the grace of God...."
"Turning 'downwind' in a constant airmass with a fixed angle of bank is going to have the same performance impact as turning with the same angle of bank in a non-moving airmass"
Please consider this as I have witnessed this many times. Ie holding in very strong winds.
I reduced angle of bank to prevent excessive IAS loss.
Ground speed heading west is IAS minus wind. ( the Perth Westerly, sea breeze can be quite strong in high temperature days)
Ground speed heading east is IAS plus wind.
Inertia must be increased quickly therefore IAS will drop until ground speed equals IAS plus wind.
Sometimes this requires over a 50 knot increase in a short time.
Please consider this as I have witnessed this many times. Ie holding in very strong winds.
I reduced angle of bank to prevent excessive IAS loss.
Ground speed heading west is IAS minus wind. ( the Perth Westerly, sea breeze can be quite strong in high temperature days)
Ground speed heading east is IAS plus wind.
Inertia must be increased quickly therefore IAS will drop until ground speed equals IAS plus wind.
Sometimes this requires over a 50 knot increase in a short time.
Dragons of the downwind turn - Australian Flying
Turning downwind in a stiff wind relative to the aircraft's indicated IAS, be it in a Mallard or a 747 is akin to a windshear event. Simple inertia. A320 I flew, somewhat between those two weights of aircraft, on full automatics gave me an 'airspeed low' warning doing just that several times in my short time on the plastic fantastic. Gentlemen and ladies this is real threat, forget CRM threats, even helicopters have the same problem. Not saying this is the cause of the sadly fatal accident-simply commenting on a previous poster.
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What seems to have been missed is that to recover from the incipient spin one would normally have input hard right rudder reduced aileron and stopped the turn. In his situation the pilot did not have that option as that would have put him out over the crowd at best or into the city, even worse. He had no option but to continue the turn and accept the consequences.
While getting into the situation in the first place was not good, ultimately he may have sacrificed himself and his crew to save other lives. RIP
While getting into the situation in the first place was not good, ultimately he may have sacrificed himself and his crew to save other lives. RIP
"Turning 'downwind' in a constant airmass with a fixed angle of bank is going to have the same performance impact as turning with the same angle of bank in a non-moving airmass"
Please consider this as I have witnessed this many times. Ie holding in very strong winds.
I reduced angle of bank to prevent excessive IAS loss.
Ground speed heading west is IAS minus wind. ( the Perth Westerly, sea breeze can be quite strong in high temperature days)
Ground speed heading east is IAS plus wind.
Inertia must be increased quickly therefore IAS will drop until ground speed equals IAS plus wind.
Sometimes this requires over a 50 knot increase in a short time.
Please consider this as I have witnessed this many times. Ie holding in very strong winds.
I reduced angle of bank to prevent excessive IAS loss.
Ground speed heading west is IAS minus wind. ( the Perth Westerly, sea breeze can be quite strong in high temperature days)
Ground speed heading east is IAS plus wind.
Inertia must be increased quickly therefore IAS will drop until ground speed equals IAS plus wind.
Sometimes this requires over a 50 knot increase in a short time.
There is a danger with low level turns in strong winds associated with visual illusions, but performance remains the same.
Loss of performance descending from higher speed "free stream" winds experienced at 500' on downwind on a hot, windy day into disturbed and varying friction layer winds close to the ground..
Normal wind shear.
Even a hot and windy day at Perth airport is nasty enough. There are obvious gust pocket ripples on the footage of the Swan River.
Normal wind shear.
Even a hot and windy day at Perth airport is nasty enough. There are obvious gust pocket ripples on the footage of the Swan River.
Thanks RenegadeMan, you have saved me a whole bunch of typing. I agree completely.
For those that think this is a 'momentum' issue I offer the following:
Momentum is a vector value. The formula is p=mv, p being inertia, m being mass, v being velocity. In our example mass is constant.
Nil wind, aircraft 100 knots, turning through 180 degrees, the velocity change is 100 knots forward to 100 knots in the reverse direction (both airspeed and ground speed), so a 200 knot vector change.
If you are going from a 50 knot headwind to a 50 knot tailwind, the airspeed change is still 100 knots ahead to 100 knots in the opposite direction. So, 200 knots velocity change. If you want to work in grounspeed, it will be 50 knots (100 kts airspeed less 50 kts headwind) to 150 knot in the opposite direction (100 kts plus tailwind of 50 kts). So, the velocity change is still 200 kts, the exact same value as nil wind. As mass is constant and velocity change is the same, the change in inertia is identical in both cases.
For those that think this is a 'momentum' issue I offer the following:
Momentum is a vector value. The formula is p=mv, p being inertia, m being mass, v being velocity. In our example mass is constant.
Nil wind, aircraft 100 knots, turning through 180 degrees, the velocity change is 100 knots forward to 100 knots in the reverse direction (both airspeed and ground speed), so a 200 knot vector change.
If you are going from a 50 knot headwind to a 50 knot tailwind, the airspeed change is still 100 knots ahead to 100 knots in the opposite direction. So, 200 knots velocity change. If you want to work in grounspeed, it will be 50 knots (100 kts airspeed less 50 kts headwind) to 150 knot in the opposite direction (100 kts plus tailwind of 50 kts). So, the velocity change is still 200 kts, the exact same value as nil wind. As mass is constant and velocity change is the same, the change in inertia is identical in both cases.
The Headmaster, you defeated yourself with your own argument. Velocity is about groundspeed, not airspeed. Inertia does indeed need to be considered and is a problem at low altitude because it is exacerbated by the unrelated but relevant issue of perception as well as the lack of recovery space if it goes wrong. Third factor: inexperience.
At normal turn rates and altitudes it is simply not noticed but combine the other factors and it is a definite threat.
At normal turn rates and altitudes it is simply not noticed but combine the other factors and it is a definite threat.
I read 120 hours experience on type. I can't help but feel that this is relevant along with recency which we are not aware of.
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The common trait is the nose dropping, unnoticed, during an increasing-bank turn with no apparent attempt to roll off the bank. You may well be right by saying "and make a better display" but the fact is none of those pilots realised it until it was too late (Perth Mallard full-right roll control on impact).
Crash of a Grumman G-73 Mallard in Perth: 2 killed | B3A Aircraft Accidents Archives
Crash of a Grumman G-73 Mallard in Perth: 2 killed | B3A Aircraft Accidents Archives
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It appears an approach made downwind, then a 180 turn at low altitude, aussie flags in video show a strongish wind, so if there was a couple of shear levels which is possible, then once the turn started it was game over, the aircraft was unfortunately lost.
From reading the manual it appears this is a beast that is not to be taken for granted and will bite the unwary and careless.
The pax would have been terrified in her last moments, unfortunately.
While there are no data recorders, enough video footage, to do a frame by frame analysis and work out if there was a Shear event or two.
The turn at low altitude was never a good idea.
From reading the manual it appears this is a beast that is not to be taken for granted and will bite the unwary and careless.
The pax would have been terrified in her last moments, unfortunately.
While there are no data recorders, enough video footage, to do a frame by frame analysis and work out if there was a Shear event or two.
The turn at low altitude was never a good idea.
The Headmaster, you defeated yourself with your own argument. Velocity is about groundspeed, not airspeed. Inertia does indeed need to be considered and is a problem at low altitude because it is exacerbated by the unrelated but relevant issue of perception as well as the lack of recovery space if it goes wrong. Third factor: inexperience.
At normal turn rates and altitudes it is simply not noticed but combine the other factors and it is a definite threat.
At normal turn rates and altitudes it is simply not noticed but combine the other factors and it is a definite threat.
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The common trait is the nose dropping, unnoticed, during an increasing-bank turn with no apparent attempt to roll off the bank. You may well be right by saying "and make a better display" but the fact is none of those pilots realised it until it was too late (Perth Mallard full-right roll control on impact).
Crash of a Grumman G-73 Mallard in Perth: 2 killed | B3A Aircraft Accidents Archives
Crash of a Grumman G-73 Mallard in Perth: 2 killed | B3A Aircraft Accidents Archives
The common trait is the nose dropping, unnoticed, during an increasing-bank turn with no apparent attempt to roll off the bank. You may well be right by saying "and make a better display" but the fact is none of those pilots realised it until it was too late (Perth Mallard full-right roll control on impact).
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I wasn't there, but Flight radar track is interesting inasmuch he had completed one circuit and was coming back for another with touchdown. The box is not marked obviously but coming in with much tighter turn required for second pass.
Anyone who was there have comments?
http://https://www.flightradar24.com...vh-cqa#c464eb9
Anyone who was there have comments?
http://https://www.flightradar24.com...vh-cqa#c464eb9
