Midair Collision over Denver • Hacker News Board

Re: Midair Collision over Denver

#191

Post by lbriner » Thu, May 13, 2021, 4:31 PM UTC

elliekelly wrote: post #111

azalemeth wrote: post #33

Earlier quoted context omitted.

Indeed. Something else I'd like to point out is that it might seem easy to 'blame the Cirrus' pilot or them call out for inattention, but doing so by itself isn't helpful. Aviation is so safe partly because it has managed to turn a culture of blame into a culture of continuous improvement and shared learning: I'd be very surprised if the airport's procedures came out of this unmodified, for example.

I’ve probably mentioned this book on HN a hundred times but “Black Box Thinking” discusses the aviation culture of avoiding blame and making sure a problem isn’t repeated and how other industries (like medicine) would benefit hugely from a similar approach. It’s really interesting.

I'm not sure how scalable this is in modern penny-pinching times. In the old days, airlines had to prove they were safe to attract business and this involved accepting that certain practices were harmful and they were therefore improved.

Once we got to the 1980s, we had so many airlines trying to survive that corners were cut, recommendations were not followed and various accidents were essentially negligent.

Now that lots of smaller airlines have been merged into larger ones, we now have Boeing type problems where the cost of manufacture, safety and development is so much higher than before, no-one wants to put a new plane through the whole approvals process, we just want to re-badge a 737 and get it into service.

Similar things happen on the railways in the UK where we have the RAIB to do a similar "no-blame" analysis of a crash/accident yet still time and time again, the same problems surface - lack of preparation, lack of training and lack of following procedures.

Re: Midair Collision over Denver

#192

Post by toast0 » Thu, May 13, 2021, 4:32 PM UTC

cmckn wrote: post #43

I've spent a decent amount of time at Centennial; it's one of the busiest general aviation airports in the country. There's a great restaurant on site that you can watch the runways from. After this incident, the restaurant is probably as close as I'd get to a Cirrus. :)

I don't see how this incident would make or break your impression of the Cirrus.

From the picture, the plane at rest is pretty messed up, but all occupants are safe, and pending investigation, there doesn't seem to be a sign of mechanical error involved.

Flying in (or near) small planes has a lot of risk, but I don't see how this incident would change your impression of this one manufacturer's planes.

Re: Midair Collision over Denver

#193

Post by londons_explore » Thu, May 13, 2021, 4:49 PM UTC

stevehawk wrote: post #163

cesarb wrote: post #117

Earlier quoted context omitted.

> The plane flying missing half the fuselage suggests to me that fuselage was excessively strong (and therefore heavy and expensive). It's probably the opposite: that the fuselage was only strong enough to resist the air pressure differential, and that the real structural component was the cabin floor. And that, luckily, the control cables for the tail were routed through the cabin floor, instead of through the top o…

It's not the cabin floor. it's what the cabin floor is attached to. Most fuselages have all of their longitudinal strength in their stringers, which are usually run along the floor. If the Cirrus had ripped through the bottom of that plane and not the top then that jet would have torn apart.

Stringers in a plane seem akin to stringers in a car frame... Cars have moved away to unibody designs (where the shell of the car is also the structure) because it is stronger, lighter and cheaper. Unibody designs have been the norm for almost 100 years now.

Re: Midair Collision over Denver

#194

Post by shadowgovt » Thu, May 13, 2021, 4:59 PM UTC

nickcw wrote: post #7

Just in case anyone (like me) is thinking - wait did that aeroplane have a parachute? From: https://en.m.wikipedia.org/wiki/Cirrus_Airframe_Parachute_Sy... The Cirrus Airframe Parachute System (CAPS) is a whole-plane ballistic parachute recovery system designed specifically for Cirrus Aircraft's line of general aviation light aircraft including the SR20, SR22 and SF50. The design became the first of its kind to becom…

I remember when these were being tested. Some of the testing was done at the NASA Langley center, which still today specializes in airframes in addition to space... They have a whole-airframe catapult and drop system.

These parachutes have been an absolute game-changer for small aircraft pilot survival. It's unlikely this kind of collision would have been survivable for the small-plane pilot 25 years ago.

Re: Midair Collision over Denver

#195

Post by js2 » Thu, May 13, 2021, 5:00 PM UTC

ordu wrote: post #28

gresrun wrote: post #2

ATC comms with visualization: https://www.youtube.com/watch?v=f5tb2dVWJqc

The pilot is speaking about failed engine after the collision, like it is nothing. Fascinating. I'd be shouting something obscene in such a situation. For half an hour at least, I think.

I thought he sounded just a little rattled after he was on the ground. As calm as his demeanor was right after the collision, there had to have been some adrenaline going in landing that plane.

Re: Midair Collision over Denver

#196

Post by cmckn » Thu, May 13, 2021, 5:01 PM UTC

toast0 wrote: post #192

cmckn wrote: post #43

I've spent a decent amount of time at Centennial; it's one of the busiest general aviation airports in the country. There's a great restaurant on site that you can watch the runways from. After this incident, the restaurant is probably as close as I'd get to a Cirrus. :)

I don't see how this incident would make or break your impression of the Cirrus. From the picture, the plane at rest is pretty messed up, but all occupants are safe, and pending investigation, there doesn't seem to be a sign of mechanical error involved. Flying in (or near) small planes has a lot of risk, but I don't see how this incident would change your impression of this one manufacturer's planes.

Oh no, my point was just that I’d be wary of getting in a small plane, and Cirrus was the craft mentioned in the article. I remember seeing a lot of them at this airport (though they’re probably outnumbered by Cesna’s, lots of small-time fliers there).

Re: Midair Collision over Denver

#197

Post by MaxBarraclough » Thu, May 13, 2021, 5:03 PM UTC

cameldrv wrote: post #174

MaxBarraclough wrote: post #138

Earlier quoted context omitted.

What's the risk to the people below? I'm reminded of a 2011 airshow crash of a Red Arrows T1 jet which, at least according to this account, [0] may have involved the pilot heroically making the decision not to personally eject, but to crash the aircraft away from crowded areas, perishing as a result. Of course, the aircraft itself had no parachute, unlike a Cirrus. (Also, I'm uncertain if that account of the incident…

There’s a huge difference in the danger to those on the ground between an 15000 lb fighter jet going hundreds of mph and a small 3000 lb airplane descending at about 15 mph (plus the wind speed). It’s possible that the Cirrus could hurt or kill someone but I don’t think it’s happened in the about 100 parachute activations so far.

> There’s a huge difference

Of course there is, that's the reason I emphasised it.

> I don’t think it’s happened in the about 100 parachute activations so far

That's good, although there could be a selection effect there: pilots might be more hesitant to deploy it if they think the falling aircraft could do harm.

Re: Midair Collision over Denver

#198

Post by throwaway330935 » Thu, May 13, 2021, 5:04 PM UTC

throwaway0a5e wrote: post #137

mdip wrote: post #62

Wow, that's incredible. Goes to show that people do walk away from plane crashes with some regularity. My father was a pilot[0]. He sold his plane about 15 years ago (to a group of owners, one of which was a priest, I'm sure there's a joke in there). A few of winters later, he was called out to Romeo Airport; the pilot flying the plane that was formerly his had crashed the aircraft a few miles short of the runway in…

> The weight is so critical that the 7-seat plane can realistically only seat 4-5 adults. I remember being shocked that they had to weigh the paint they applied when he had the plane re-painted. I used to work in general aviation. If my eyes could fly a loop in my skull they would have. Were the occupants required to use the bathroom before flying? That's how much weight you're potentially saving by weighing the pain…

>in order to get your mixture into the right ballpark

This makes perfect sense. I'm using a kitchen scale to measure the 2-part silicone mixture that I'm using for making toys, not because weight is critical but because it needs to be right for curing. I should do similar when mixing epoxy, but I always eyeball that for some reason. Maybe has to do with cost, it's $10-20 worth of silicone I'm mixing, and usually a quarter worth of epoxy, just due to quantities involved.

Re: Midair Collision over Denver

#199

Post by ordu » Thu, May 13, 2021, 5:05 PM UTC

lbriner wrote: post #187

throwaway0a5e wrote: post #78

Earlier quoted context omitted.

When people encounter emergency situations in domains they are familiar with they tend to do a pretty good job of rolling with it.

Exactly. You either panic and run around screaming and then you die or you could try and take control and you might live. It's no different than most of us driving a car. If a tyre blows out, most of us wouldn't scream and close our eyes, we would try and steer to safety.

> You either panic and run around screaming and then you die or you could try and take control and you might live.

It is not so black and white. One might (and normal person should) feel a stress reaction with rising levels adrenaline and suchlike in his bloodstream, and it is normal, it might even be beneficial, if one was trained to benefit from this mind state. I become more resolute from this, more concentrated than usual, sometimes even more concentrated than it is good for me because I might miss some important detail.

> If a tyre blows out, most of us wouldn't scream and close our eyes, we would try and steer to safety.

I never was in this situation with a blown tyre, but I was in some other situations when there was a danger to my life (or I believed that it was) I become extremely concentrated, almost silent (except for occasional curses), but when I needed to communicate, I did it loudly and with a good deal of swearing. I think that communication for me in these situations is like a distracting hindrance, so if I need to do it, I'll do it in a way that will make it unnecessary to repeat it.

The communication of the pilot have not a hint of his emotions. My mind was blown not because of his perfect actions (I expect perfect actions from a professional), not even because the lack of swearing. It is the tone of his voice, it is completely composed, almost relaxed. I can imagine myself in this situation restraining from shouting and from swearing, but my emotional tension would leak through my voice, I wouldn't even try to hide it.

Re: Midair Collision over Denver

#200

Post by jrockway » Thu, May 13, 2021, 5:13 PM UTC

tialaramex wrote: post #150

captainredbeard wrote: post #123

Earlier quoted context omitted.

Well you wouldn’t pull the chute. The plane has lift when it has forward motion at a non stalling angle of attack. It would become a glider until reaching stall speed

No, you should probably pull the chute. Yes you're gliding right now, but whilst that's better than just falling uncontrolled from the sky it's no guarantee you'll walk away. Now if you're gliding... right towards a perfectly nice runway you were already lined up on then CAPS is likely the wrong call, not least because you may already be too low. But if you're just in the middle of nowhere then CAPS is much safer tha…

Here's an analysis of the CAPS system's safety record: https://www.youtube.com/watch?v=zT58pzY41wA (contains some good footage of an SR22 parachuting into the ocean, and into the ground).

This is a good overview on the survivability of water landings: https://www.youtube.com/watch?v=0LwGYBBhTss. I haven't watched the video recently but I think even a 172 that cartwheels after landing has a pretty good survivability rate, something like 90%. Parachute is a nice to have, of course.