French MP and billionaire Olivier Dassault dies in helicopter crash
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Full report here
https://bea.aero/fileadmin/user_uplo...2_02_final.pdf
Yea, trees. Report is worth reading. Espcially this part:
Dans le cas de verres solaires sans correction optique, la diminution de la quantité
de lumière transmise à la rétine conduit à l’augmentation du diamètre pupillaire
ce qui diminue la capacité d’adaptation à la distance de l’objet. Les indices élevés
fréquemment adoptés par les pilotes, généralement 3, pour ne pas être éblouis,
accroissent l’obscurité des zones les moins éclairées, comme le panneau des
instruments ou bien, comme ici, la zone ombragée de l’arbre le plus élevé. Pour
les pilotes soumis à la mention VML, l’utilisation de verres solaires non corrigés
est proscrite.
De nombreux travaux ont également été menés sur le vieillissement et ses
conséquences. L’une des capacités la plus impactée par le vieillissement est la vision,
et certains essais montrent le caractère contraignant du contraste. La sensibilité au
contraste est un élément fondamental de la vision des motifs et fait référence à la
capacité de discriminer des variations de luminance dans une image.
L’acuité visuelle, c’est-à-dire la capacité à discriminer les détails fins d’un objet
à 100 % de contraste, va naturellement diminuer. Stable jusqu’à environ 40 ans,
l’acuité visuelle diminue de façon linéaire au-delà puis la diminution s’accentue
après 70 ans. Cette diminution s’accentue en situation de faible contraste et de faible
luminosité.
La sensibilité lumineuse en condition scotopique diminue avec l’âge, se traduisant
par un allongement du temps d’adaptation à l’obscurité.
Mr Dassault, who held a full ATPL(A), had no helicopter license and flew his helicopter dual with an instructor, who himself had retired from an airplane pilot career, and kept himself busy flying helicopters.
https://bea.aero/fileadmin/user_uplo...2_02_final.pdf
Yea, trees. Report is worth reading. Espcially this part:
Dans le cas de verres solaires sans correction optique, la diminution de la quantité
de lumière transmise à la rétine conduit à l’augmentation du diamètre pupillaire
ce qui diminue la capacité d’adaptation à la distance de l’objet. Les indices élevés
fréquemment adoptés par les pilotes, généralement 3, pour ne pas être éblouis,
accroissent l’obscurité des zones les moins éclairées, comme le panneau des
instruments ou bien, comme ici, la zone ombragée de l’arbre le plus élevé. Pour
les pilotes soumis à la mention VML, l’utilisation de verres solaires non corrigés
est proscrite.
De nombreux travaux ont également été menés sur le vieillissement et ses
conséquences. L’une des capacités la plus impactée par le vieillissement est la vision,
et certains essais montrent le caractère contraignant du contraste. La sensibilité au
contraste est un élément fondamental de la vision des motifs et fait référence à la
capacité de discriminer des variations de luminance dans une image.
L’acuité visuelle, c’est-à-dire la capacité à discriminer les détails fins d’un objet
à 100 % de contraste, va naturellement diminuer. Stable jusqu’à environ 40 ans,
l’acuité visuelle diminue de façon linéaire au-delà puis la diminution s’accentue
après 70 ans. Cette diminution s’accentue en situation de faible contraste et de faible
luminosité.
La sensibilité lumineuse en condition scotopique diminue avec l’âge, se traduisant
par un allongement du temps d’adaptation à l’obscurité.
Mr Dassault, who held a full ATPL(A), had no helicopter license and flew his helicopter dual with an instructor, who himself had retired from an airplane pilot career, and kept himself busy flying helicopters.
Last edited by 172510; 30th Jun 2023 at 09:24.
The English version of the report is at https://bea.aero/fileadmin/user_uplo...-0089.en.1.pdf, and the section that @172510 refers to reads:
In the case of sunglasses without an optical correction, the reduction in the quantity of light transmitted to the retina leads to an increase in the pupil diameter which reduces the capacity of adaptation to the distance of the object. The high indexes frequently adopted by pilots, generally 3, to avoid being dazzled, increase the darkness of the least lit areas, such as the instrument panel or, as here, the shaded area of the tallest tree. For pilots subject to the VML limitation, the wearing of uncorrected sunglasses is prohibited.
Much work has also been done on ageing and its consequences. One of the abilities the most impacted by ageing is vision, and some trials show the nullifying character of contrast. The sensitivity to contrast is a fundamental part of pattern vision and refers to the ability to discriminate variations in luminance in an image.
Visual acuity, the ability to discriminate fine details in an object with 100% contrast, will naturally decrease. Stable until reaching an age of around 40 years, visual acuity decreases linearly after that, with the decrease becoming more pronounced after the age of 70 years. This decrease is accentuated in low contrast and low light situations.
Light sensitivity in scotopic conditions decreases with age, resulting in a longer adaptation time to darkness.
Natural ageing progressively modifies the neurophysiological, perceptual and cognitive aspects of vision.
In the case of sunglasses without an optical correction, the reduction in the quantity of light transmitted to the retina leads to an increase in the pupil diameter which reduces the capacity of adaptation to the distance of the object. The high indexes frequently adopted by pilots, generally 3, to avoid being dazzled, increase the darkness of the least lit areas, such as the instrument panel or, as here, the shaded area of the tallest tree. For pilots subject to the VML limitation, the wearing of uncorrected sunglasses is prohibited.
Much work has also been done on ageing and its consequences. One of the abilities the most impacted by ageing is vision, and some trials show the nullifying character of contrast. The sensitivity to contrast is a fundamental part of pattern vision and refers to the ability to discriminate variations in luminance in an image.
Visual acuity, the ability to discriminate fine details in an object with 100% contrast, will naturally decrease. Stable until reaching an age of around 40 years, visual acuity decreases linearly after that, with the decrease becoming more pronounced after the age of 70 years. This decrease is accentuated in low contrast and low light situations.
Light sensitivity in scotopic conditions decreases with age, resulting in a longer adaptation time to darkness.
Natural ageing progressively modifies the neurophysiological, perceptual and cognitive aspects of vision.
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I think that is most noticeable when you try to read in different light conditions with and without glasses - my correction for reading is between 1.5 and 2 dioptres but I can read unaided in bright conditions because of the high contrast - as soon as the light levels reduce from that I have to reach for my glasses.
If you artificially reduce your light levels with sunglasses, down goes your contrast.
If you artificially reduce your light levels with sunglasses, down goes your contrast.
This paragraph made me pay attention
When the distance vision is relatively preserved, certain subjects think that they can omit wearing glasses, except if they are forced to do so by necessity (reading on-board documents or instruments for pilots). This choice, made here by the pilot, necessarily implies accepting the significant deterioration of the near vision and intermediate vision. The result of this is that, unlike a subject who does not need such a correction, it is more difficult to detect and identify an apparently moving object which may "enter" the field of vision. Thus the monitoring of the flight parameters and outside obstacles during the takeoff may have been slowed down by the adaptation time caused by the alternation between intermediate and distant vision.
I’m 73, have the start of cataracts which affect my sight in bright light. I ride a motorcycle with far too much power at silly speeds in the south of France generally in the morning before it gets too hot. The loss of vision from bright sunlight to shade is incredible. To counteract the brief periods of semi blindness I look at the road surface ..important as a diesel spillage is game over.
Evening paragliding is more difficult and I sacrifice looking at my instruments with corrected dark Polaroid glasses and avoid situations where conflicting traffic is up sun. (Often by landing and waiting until others have as well).
My wife hasn’t driven for decades at night as women have more cones than rods..the former are for colour perception whilst the latter work in low light.
‘It’s about understanding your limits like look out at junctions wrt cyclists and the width of the windscreen pillars.
Evening paragliding is more difficult and I sacrifice looking at my instruments with corrected dark Polaroid glasses and avoid situations where conflicting traffic is up sun. (Often by landing and waiting until others have as well).
My wife hasn’t driven for decades at night as women have more cones than rods..the former are for colour perception whilst the latter work in low light.
‘It’s about understanding your limits like look out at junctions wrt cyclists and the width of the windscreen pillars.
Brilliant!
Originally Posted by [email protected]
I think that is most noticeable when you try to read in different light conditions with and without glasses - my correction for reading is between 1.5 and 2 dioptres but I can read unaided in bright conditions because of the high contrast - as soon as the light levels reduce from that I have to reach for my glasses.
If you artificially reduce your light levels with sunglasses, down goes your contrast.
If you artificially reduce your light levels with sunglasses, down goes your contrast.
I guess one could call the problem "contrast" but the real effect is optical aberration / blurring / smearing of the image not being focused on a one-to-one correspondence between the scene and the retina.
I still recall in my 40s standing up in the cube farm from a long day at the computer monitor and noting that everything more than 20 feet or so was a bit blurry, like a fog had rolled in - the lenses were no longer elastic enough to flatten out rapidly when the lens muscles relaxed. Now my lenses appear to be stiff enough the little muscles that should deform them no longer can. At least I can see well enough in the distance, though there is some correctable astigmatism that is annoying. As long as there are no highway eye charts and I have cheap readers to see the speedometer I am still good to drive.
That "adaptation time" in the report is, I think, the time required for the elastic capsule of the lens to change shape as the muscles squeeze or release it. At the age mentioned, I suspect that adaptation time is approaching infinity.
Below the Glidepath - not correcting
The eyesight and visual perception only became issues because a thorough appreciation of the HLS and its hazards was either not completed or not completed fully. If visual acuity, ambient light levels and a low sun were critical factors for safe operation, the HLS was not within the acceptable risk envelope for the pilot(s). Sadly, still nothing remotely unique about this tragic accident.
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What a very very interesting and informative post concernign the vsioin degradation issues (being just past70 myself) . As to rich people in helicopters perhaps many such are less risk averse than most of us perhaps they consider their time more valuable than their life.
Much discussion as to why rich people expose themselves to risk as if, by dint of them being wealthy, their life is somehow more valuable than the rest of us
Nobody sets out kill themselves but at the same time we all want to live a life and doing things that present an elevated risk makes some feel even more alive
I suppose they could wrap themselves up in cotton wool but the grim reaper will still get them in the end
Nobody sets out kill themselves but at the same time we all want to live a life and doing things that present an elevated risk makes some feel even more alive
I suppose they could wrap themselves up in cotton wool but the grim reaper will still get them in the end
The eyesight and visual perception only became issues because a thorough appreciation of the HLS and its hazards was either not completed or not completed fully. If visual acuity, ambient light levels and a low sun were critical factors for safe operation, the HLS was not within the acceptable risk envelope for the pilot(s). Sadly, still nothing remotely unique about this tragic accident.
What we see is informal (illegal) training, complacency because they had landed there numerous times. And compete absence of risk assessment. Not blasting the pilots. Can happen to all of us. But don't blame it on my eyesight!
What happened to the good old Triple-S? Sun, surface, slope. A good reminder that this not only applies to the confined *landings*. But also to take-offs. The pilots may have totally forgotten about the presence of the trees (not because they looked, and couldn't see the trees due to old age, but because they didn't look):
The [horizontal] distance travelled by the helicopter from the point of take-off to the point of impact with the tree branches, of approximately 8.50 m, suggests that, irrespective of a possible drift of the helicopter, it was probably deliberately put into forward flight in order to start horizontal acceleration. The helicopter’s manoeuvre with a nose-down attitude, observed by a witness, is in line with this hypothesis of the helicopter deliberately being put into forward flight.
An old guy without a huge amount of helicopter experience (est 1400 hours in the report), in a confined area without his glasses on giving illegal instruction to another old guy with negligible helicopter time in poor light conditions - what could possibly go wrong with that?
I think the eyesight factor is a major cause, in part because he couldn't see the trees ahead but primarily because he didn't notice the drift during the vertical climb - basic scanning to a lateral marker would have picked this up straight away.
5 S recce is great but picking good markers is even more important.
If the 'passenger' in the LHS was flying the departure, all the major obstacles were on the other side of the aircraft where the instructor was sitting and his inexperience would make a drift in a vertical climb quite likely without verbal or physical intervention from the instructor.
If the instructor was flying the departure the his proximity to the obstacles would, in my mind, have led him to drift deliberately left in the vertical climb - presuming he could actually see the obstacles well enough.
Either way, a very avoidable accident with tragic consequences.
I think the eyesight factor is a major cause, in part because he couldn't see the trees ahead but primarily because he didn't notice the drift during the vertical climb - basic scanning to a lateral marker would have picked this up straight away.
5 S recce is great but picking good markers is even more important.
If the 'passenger' in the LHS was flying the departure, all the major obstacles were on the other side of the aircraft where the instructor was sitting and his inexperience would make a drift in a vertical climb quite likely without verbal or physical intervention from the instructor.
If the instructor was flying the departure the his proximity to the obstacles would, in my mind, have led him to drift deliberately left in the vertical climb - presuming he could actually see the obstacles well enough.
Either way, a very avoidable accident with tragic consequences.
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Another point: According to the investigation the two pilots (or passengers, we don't know) were already fatally injured before the impact with the ground:
It was also noted that the damage occurred during a single rotation of the rotor. Very different from gently grazing a few leaves with the rotor tips. These mishap pilots must have gone full in.
1.16.1 Separation of tail boom and seats
The collision of the main rotor blades with the tree branches led to an instantaneous and violent overtorque on the main rotor hub.
[...]
The accelerations generated during the overtorque on the main rotor hub exceeded the lateral accelerations which could be borne by the two front seats, leading to them being torn from the helicopter cabin floor.
The collision of the main rotor blades with the tree branches led to an instantaneous and violent overtorque on the main rotor hub.
[...]
The accelerations generated during the overtorque on the main rotor hub exceeded the lateral accelerations which could be borne by the two front seats, leading to them being torn from the helicopter cabin floor.
1.15 Survival aspects
The results of the autopsy showed that the internal injuries received by the two people on board, due to the acceleration experienced by their bodies when the main rotor collided with the trees followed by the rotation of the airframe about its yaw axis left no chance of survival.
The results of the autopsy showed that the internal injuries received by the two people on board, due to the acceleration experienced by their bodies when the main rotor collided with the trees followed by the rotation of the airframe about its yaw axis left no chance of survival.
It was also noted that the damage occurred during a single rotation of the rotor. Very different from gently grazing a few leaves with the rotor tips. These mishap pilots must have gone full in.
Damage resulting from the collision with the branches was identified on the red and yellow blades over a length of around 2.60 m from the blade tips. The red blade had at least seven points of damage, the yellow blade had suffered at least one impact while the blue blade did not seem to have suffered an impact.
The distribution of the damage on the main rotor blades tends to show that it occurred during a single rotation of the rotor. A succession of impacts over several rotations would probably not have left the blue blade without visible impact marks.
The distribution of the damage on the main rotor blades tends to show that it occurred during a single rotation of the rotor. A succession of impacts over several rotations would probably not have left the blue blade without visible impact marks.
[QUOTE=Hot and Hi;11460155]Another point: According to the investigation the two pilots (or passengers, we don't know) were already fatally injured before the impact with the ground:
This is surprising, I can’t quite get my head around this one. That is one hell on an acceleration to kill a human that quickly. Is it possible it’s a translation issue? It just does not quite sound right.
This is surprising, I can’t quite get my head around this one. That is one hell on an acceleration to kill a human that quickly. Is it possible it’s a translation issue? It just does not quite sound right.
If the main rotor blades were significantly damaged the out of balance forces would produce massive lateral G-loads that would be well beyond what a human neck and spine could cope with.
It has happened in past accidents where blades have been damaged or separated - the lateral g-load can be massive and immediate.
It has happened in past accidents where blades have been damaged or separated - the lateral g-load can be massive and immediate.
Especially considering the age of the pilots - reduced muscle strength and bone density in your 70's
If the main rotor blades were significantly damaged the out of balance forces would produce massive lateral G-loads that would be well beyond what a human neck and spine could cope with.
It has happened in past accidents where blades have been damaged or separated - the lateral g-load can be massive and immediate.
It has happened in past accidents where blades have been damaged or separated - the lateral g-load can be massive and immediate.
Interesting I don’t know enough about those forces to comment other than to say I’m surprised. It would be interesting to know the potential G values involved and how they separated injuries from the aircraft hitting the ground.
It is a good comment you make about the age of the crew Crab.
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