Roy Halladay - Icon A5 Crash

[Alan_A 1,650]

9 hours ago, Chock said:

In other news, I see some radio pillock in the US (Michael Felger) on Boston Sports Radio has actually gone on air saying that Halladay was a moronic thrill seeker who deserved to die for having flown that aerolane

He's apparently apologized... but it's not going over well.  A Boston Globe columnist calls for his suspension.

Can't say much good about U.S. sports talk radio.

The NTSB preliminary report on the May 8 ICON crash refers to a review of "two separate recording devices" and reports on (GPS) altitude, speed and heading information, plus power setting.

[Chock 17,769]

It's looking a lot like it will turn out to be pilot error being the conclusion of the accident investigation, if what is allegedly video footage of the Icon being flown pretty aggressively at low level just before the crash is genuine. The NTSB are apparently saying it was a 'high energy impact', so it probably was a wingtip strike if you look at how that aeroplane is being flown on the video footage, but it could have been a spin entry at low altitude I suppose. Theoretically, the Icon is a spin-resistant design and is promoted as such too, which might be a bad thing in that it's a bit like claiming the Titanic was unsinkable. since the water where the crash occurred is apparently just four feet deep, it is doubtful it was a landing gone wrong, or, if it was a landing attempt, then it'd have been an ill-advised one in that kind of draft.

[Oracle427 45]

Do not discount the fact that one can not judge height when flying over a featureless body of water or a field covered in snow with no trees or man made objects in the field of view.

I believe it is very reasonable to assume that the aircraft was flown under control right into the water. No stall, no bank, no wheels down, no spin. It wouldn't the first time and sadly it won't be the last.

I have done landings on snow covered fields and believe me it can sometimes be very difficult to tell how high you are off the ground. I was advised while receiving this training that landing on water is much the same. The technique is to fly tail low and carefully regulate power in the descent until you contact the ground because it is risky to try and descend in a nose down attitude and flare at the correct height. You might just become a lawn dart if you do that.

Doing maneuvers at low altitude is very risky, doing it over featureless terrain increases the risk significantly. There are many NTSB reports where very lucky pilots of sea planes explained how they flew the aircraft right into a lake or river never realizing how low they were.

Catching a wingtip or flying right into the water seem the most likely scenarios. If power has been lost, a safe landing was all but assured given the aircraft is amphibious.

I can see the writing in the wall for Icon. They are going to get sued big-time for their marketing that promotes flying at low altitude. Not saying it is right, but it is going to happen and they are going to pay.

It angers and frustrates me because what I saw goes against what we are taught to do as pilots. If we want to fly that way that was filmed and described we are supposed to seek out training from professionals. Perhaps he did receive such training, but even then pilots competing in aerobatics aren't even authorized to fly very low for good reason.

[Jim Young 2,356]

According to the Icon A5 website:

Complete Aircraft Parachute (CAP)

"Safe and Sound. CAP technology has more than 300 documented lives saved, some at altitudes as low as a few hundred feet. So if you encounter the unexpected, we’ve got you covered. Literally."

https://www.iconaircraft.com/a5

[Oracle427 45]

NTSB Issues Preliminary Report on Halliday Crash https://www.avweb.com/avwebflash/news/NTSB-Issues-Preliminary-Report-on-Halliday-Crash-229948-1.html

[Chock 17,769]

Based on that preliminary report, it is looking like the impact will eventually be determined to have been as a result of a stall off a turn, at too low an altitude to effect a recovery, which is what a lot of people figured might have been the case.

If the altitude reports are correct, it's doubtful the ballistic recovery 'chute would have been much use, so the discovery of the locking pin having been left in place on the ballistic recovery system firing handle is neither here nor there with regard to the outcome for this incident, but since it should have been removed before flight, and apparently wasn't, that is potentially indicative of checklists/procedures not being followed as closely as they should, although whether that indicates an overall cavalier fashion to operational safety is a matter of conjecture.

But if the reports from eye witnesses to the crash and preceding flights in the area are given credence, it seems the aeroplane may have been flown in perhaps not the most diligent fashion, with possibly too much faith placed in the notion of the Icon's 'stall resistant' design.

[HighBypass 2,339]

I'm curious as to how "stall resistant" is interpreted, given that the report states all light aircraft in the same class as an A5 have to have a stall speed of no higher than 45 knots? Surely any aircraft is stall resistant until its stall speed is reached - even F-18s and Su-27 families will stall and quit flying. Granted - 45 knots is really rather low, and does "seem" safe, but still fast enough to kill, without a plane picking up speed in an ensuing nose-down attitude post-stall.

Does it refer to benign stall characteristics where the plane doesn't demonstrate a tendency to drop a wing or even worse when it departs? Is it that the plane gives you plenty of warning signs - buffeting, loss of control effectiveness etc?

We all know that stall speed increases in a turn, especially if you wish to remain at the same altitude.

[Oracle427 45]

This is a great question as the aircraft can clearly stall, as any aircraft will do when the critical AoA is exceeded. It must be something about the controllability of the aircraft while in a stalled state.

For example, the ailerons on a 172 should remain neutral during a stall add any deflection can result in an incipient spin entry. In the Icon, I understand that the aircraft will respond normally to aileron inputs and not enter an incipient spin. Perhaps this is the part commonly referred to as "departure from controlled flight?"

Personally, I have my doubts about a stall of any sort being part of this accident sequence. I wonder if they will be able to determine this from the available recorded data.

Regardless of what happened in the final moments, I am glad that the NTSB has shared the evidence of reckless behavior in this preliminary report. It can be a while before the final report is produced. This should serve as a warning to those who wish to test the odds. I wonder if the very ones at risk will avail themselves of this information.

[Murmur 3,941]

1 hour ago, HighBypass said:

I'm curious as to how "stall resistant" is interpreted, given that the report states all light aircraft in the same class as an A5 have to have a stall speed of no higher than 45 knots? Surely any aircraft is stall resistant until its stall speed is reached

Does it refer to benign stall characteristics where the plane doesn't demonstrate a tendency to drop a wing or even worse when it departs? Is it that the plane gives you plenty of warning signs - buffeting, loss of control effectiveness etc?

 

1 hour ago, Oracle427 said:

This is a great question as the aircraft can clearly stall, as any aircraft will do when the critical AoA is exceeded. It must be something about the controllability of the aircraft while in a stalled state.

Surprising as it may seem, it is actually possible to design an aircraft that will not enter stall.

Keep in mind that the elevator is the primary surface controlling the AoA, so if you design an aircraft whose elevator authority is not enough to reach the critical AoA of the wing, it will not stall even if you pull the yoke to the max, in theory at any speed. What will happen, is that at a certain point the nose will simply point down, but the wing will remain unstalled (and the aircraft controllable, although with limited maneuverability in the vertical plane until the aircraft recovers enough energy to stop sinking).

As far as I know, this is basically how the Icon A5 is designed. Of course the stall-resistance may be dependent on some conditions, e.g. the aircraft may be stall resistant with the cg in mid range, but able to enter stall with cg at rearmost position.

Designing a stall resistant aircraft will probably be a compromise with other aspects of the flight dynamics, giving for example limited pitch authority in some other situations where a "conventional" aircraft will remain instead more maneuverable.

[Chock 17,769]

Strictly speaking, Icon's claim for the A5 is that it is 'spin resistant', rather than 'stall resistant' as far as the marketing literature is concerned, but of course we all know that a spin is basically an asymmetric stall, so it amounts to the same thing.

How that works is like this: If you look at a plan view of the Icon A5, you'll see a dogtooth approximately halfway along the leading edge of each wing. This is the point where the Icon uses a different aerofoil outboard to the aerofoil inboard of that point. It means the inner wing should stall before the outer wing, leaving the ailerons still able to control the wing when the inner wing is stalled since the ailerons are on the outer wing. A similar thing was done on later versions of the Hawker Hunter to make it a bit less vicious aerodynamically.

Spin resistant design in private aeroplanes is nothing new though, the ERCO Ercoupe was around before WW2 and that thing didn't even have any rudder controls at all, it was designed to fly without them and marketed as being resistant to spins.

That's the theory behind how that stuff works anyway.