Midair Collision over Denver

by lunchbreak • 5 years ago

413 231 5 years ago

gresrun• 5 years ago

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

ordu2• 5 years ago

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.

NikolaeVarius• 5 years ago

This what separates professionals from the chaff

goodcanadian• 5 years ago

He might not have been aware of the full extent of the damage. He is on final; the plane is flying; he's lost an engine; he's going to land it. There is no time for anything else.

throwaway0a5e4• 5 years ago

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

neom• 5 years ago

Trusted his training. Very good pilot.

phkahler2• 5 years ago

> 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.

When you get your medical clearance, one of the things they look for is signs of psychological issues or instability. Not saying that's you, and I bet you'd do better than you think. Pilot training also IMHO makes you better at that stuff.

js2• 5 years ago

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.

xattt• 5 years ago

It’s amazing there were no casualties. The novelty of the report is the use of a rescue parachute by the Cirrus plane.

_s• 5 years ago

Private Pilot here - just thought I'd chime in quickly;

Many aviation enthusiasts / pilots first go to is to have a look at the flight data - usually available on FlightAware / FlightRadar24 and a few other websites, plus LiveATC usually can provide recordings of the flights communications to towers as well. We should refrain from using just those data points to draw conclusions to the cause; the NTSB (and other orgs) will perform an investigation and the report will be made public (both interim, and final ones), and changes are almost always made to processes / systems, and often to the virtual or physical items that led to this incident.

There are a few more photos and insights from various folks that were there at the time and captured a few moments on the reddit thread here:

https://www.reddit.com/r/flying/comments/nauck8/mid_air_just...

Note - it's incredibly rare for a midair not to result in fatalities so an incredible amount of luck all around.

sundvor• 5 years ago

Thanks, that does seem incredibly lucky indeed.

Also, I like the headline including "all parties ok".

sokoloff13• 5 years ago

It’s not incredibly rare. Around 2 in 5 midair mishaps result in no fatalities.

https://iflyamerica.org/midairs.asp

This one was incredibly lucky, especially for the Key Lime aircraft.

mannykannot7• 5 years ago

Interesting - that's higher than I would have expected, but apparently explaind by most collisions being in the pattern or otherwise near an airport (makes sense now that I think about it.) At least in the pattern, for most of the time, everyone is going in approximately the same direction (even this case.)

lbriner4• 5 years ago

My guess would be that only in the worst scenarios does a collision involve a full-impact. In most cases I would expect either or both pilots to be taking avoiding action so that you might get some more minor scrapes which allow you to limp home.

nitrogen• 5 years ago

No injuries reported. Kind of fascinating to read.

ardit33• 5 years ago

Spoiler: No one died, so it has a happy ending

nickcw• 5 years ago

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 become certified with the FAA, achieving certification in October 1998, and as of 2014 was the only aircraft ballistic parachute used as standard equipment by an aviation company.

maweki2• 5 years ago

I was wondering whether there was a mix-up in the crew count, as one pilot with a parachute saves two people and a one-person crew lands the plane.

This mostly clears it up.

Grustaf2• 5 years ago

My less charitable reading was that the pilot abandoned the Cirrus on a parachute, but then it seemed like the plane landed…

t0mas8811• 5 years ago

The more generic system is called BRS, Ballistic Recovery Systems. They deliver this as an option for many small aircraft and it's popular for experimental / home built aircraft.

One downside of the systems is that they typically have a maximum lifespan of 10 years while airframes last 50+ years. So every 10 years there is a large maintenance cost to replace/renew the parachute system. Much less an issue for a $ 800k Cirrus SR22 (like the one in this incident) than for a $ 30k old Cessna.

cookguyruffles• 5 years ago

Am I correct in saying after one usage, the parachute system generally needs replaced? I think I read this about Cirrus planes anyway

dmix• 5 years ago

The device is attributed with saving over 200 lives to date.

https://www.cirruspilots.org/Safety/CAPS-Event-History

sokoloff13• 5 years ago

That particular phrasing and calculation, suggesting that every chute deployment without fatalities represents that number of people “saved” is quite controversial and IMO not supported by an analysis of the data.

I think it’s great that the system exists, it has undoubtedly saved lives, but unless Cirrus crashes are overwhelmingly fatal compared to other airplanes, it’s overstating “fatal accidents turned into non-fatal accidents” by likely a factor of ~3 and number of fatalities avoided by ~4.

This type of mishap is probably the best scenario for a chute, though. I have no illusions that following a mid-air that I am still a strong favorite to bring my non-chute airplane to earth without fatalities. (The stats say I’m about a 60:40 favorite to do so.)

CAPS saves lives. CAPS has not saved the lives of every person who survived a CAPS deployment, because most of those would have survived anyway. In most off-airport arrival scenarios, I’d be wishing to have a chute.

* - One of my instructors was in command for CAPS Event #46

akouri• 5 years ago

The SR-22 also cannot recover from a spin. I would assume most of those deployments are from out of control spins. I am not sure the parachute system can be credited for saving more lives than a similar plane not-equipped, because the Cirrus _needed_ that parachute system in order to be certified.

jonplackett• 5 years ago

I don't know why this blew my mind so much, but it did.

alister• 5 years ago

What are the problems with making such a system for large passenger aircraft (perhaps with multiple parachutes)?

gecko• 5 years ago

The drastically higher speeds involved (250-300 knots airspeed, as opposed to more like 50-90 knots for GA aircraft), combined with drastically higher weights (think about the chutes needed for something like Apollo, which is nowhere near the size of a large passenger aircraft, and realize you need way more) would both be major issues. There’s also the simple fact that larger passenger aircraft tend not to fail this way, making it less likely such a system would help even if it existed.

MauranKilom• 5 years ago

I would expect the problem to be "mass goes up with size cubed, while parachute drag only goes up with size squared". I.e. you need a disproportionately larger chute (or more of them) for large aircraft. Those are dead weight in normal operation, which really hurts the economics.

mikepurvis• 5 years ago

The sibling comments make some of the same arguments, but here’s an article which also addresses it:

"An aircraft is most vulnerable during take-off and landing because it is closer to the ground (its biggest obstacle), and is travelling at low speeds and therefore is harder to manoeuvre. According to statistics from Boeing, almost three-quarters of deaths from plane crashes between 2005 and 2014 occurred during these phases of flight. But this is the time when a detachable cabin would least likely be successful at saving lives. Being closer to the ground would give the pilot much less opportunity to jettison the cabin following an incident and if it were detached it could well land in a built-up area."

https://theconversation.com/why-a-detachable-cabin-probably-...

marcinzm• 5 years ago

To add to another comment larger planes have much better redundancy (multiple engines, multiple control lines, multiple pilots, etc.) so the situations where a parachute would help are much much fewer. So weight is probably better spent on making the redundant systems even more redundant than anything else.

morcheeba• 5 years ago

I'll add on to the good points other have made here - smaller planes tend to fly out of small airports in the suburbs or the countryside. Larger planes fly out of much more urban areas, where there are a lot more obstacles, making a safe landing less probable.

Aeolun2• 5 years ago

Ah, that’s why I only read about one parachute for two passengers :D

JohnJamesRambo• 5 years ago

Thank you, I was so confused. I was thinking the pilot a genius for bringing and activating a parachute. Now I see it was just great design.

As of 1 May 2021, CAPS had been activated 122 times, 101 of which saw successful parachute deployment. In those successful deployments, there were 207 survivors and 1 fatality. No fatalities had occurred when the parachute was deployed within the certified speed and altitude parameters

londons_explore3• 5 years ago

They are some impressive numbers, but to really compare you need an expert looking at each situation and estimating the likely outcome had the CAPS system not been installed.

captainredbeard4• 5 years ago

It’s a “marquee feature” of buying a Cirrus, he didn’t just wake up and pack a chute

jmpman• 5 years ago

21 of 122 failed? That’s a concerning statistic. I’d expect closer to 99% success, not 82%. How many fatalities when the parachute failed to deploy? 100%? If so, then you have almost a 1/5 chance of dying when you engage the parachute?

ssully• 5 years ago

For those curious about seeing it in action: https://www.youtube.com/watch?v=gBCUQlF3MMU

shadowgovt• 5 years ago

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.

onion2k• 5 years ago

I find it slightly incredible that two planes ever hit each other given the size of planes compared to the volume of space they fly in. I understand that it's simple probability (small planes, big volume, but lots of flights) but it's still amazing that it happens at all.

coldtea• 5 years ago

I find it slightly incredible that two planes ever hit each other given the size of planes compared to the volume of space they fly in.

The space can be constrained though. There are "airways" (jet routes) for flights, and not that much of a volume/size ratio when the volume concerns areas near airports -- where many planes approach, exit, are asked to circle in a holding pattern, etc.

So it's not like the whole sky is their domain...

freetime2• 5 years ago

Less incredible in this case since it was two planes landing on parallel runways at the same time.

t0mas8811• 5 years ago

The probability is much higher in terminal airspace because all planes are going to or coming from the airport so they are on converging paths by definition.

And better GNSS based navigation equipment is now making it more likely than 20 years ago. The historical accuracy was such that planes where often a bit offset left or right off the route giving extra separation. Now the accuracy is so good that planes going opposite direction on the same route are passing exactly bang in the middle on top/below each other.

throwawaygimp2• 5 years ago

Yea, this is a really good point that isn't well known.

We've improved GNSS significantly, but the technology to avoid collisions hasn't been widely deployed, even though it's orders of magnitude less complicated than high accuracy GNSS on the whole

So... a random dilution of precision generator could... save lives? ha.

mnw21cam3• 5 years ago

Planes going opposite directions on the same route are meant to be at different altitudes. Altimeters have been quite accurate for a long time.

KuiN• 5 years ago

The ability for planes to follow these highly accurate common flight paths was a contributing factor in the Gol flight 1907 mid-air collision in Brazil [0]. (That, plus ATC clearing the two planes at the same altitude _and_ both having TCAS (Traffic Collision Avoidance System) switched off). William Langewiesche published a great long-form article about the disaster called "The Devil at 37,0000ft" that's well worth reading if that's your sort of thing [1].

[0] https://en.wikipedia.org/wiki/Gol_Linhas_Aéreas_Flight_1907

[1] https://www.vanityfair.com/culture/2009/01/air_crash200901

DonHopkins• 5 years ago

"Big Sky Theory"

https://en.wikipedia.org/wiki/Big_sky_theory

In aviation, the Big Sky Theory is that two randomly flying bodies are very unlikely to collide, as the three-dimensional space is so large relative to the bodies. Some aviation safety rules involving altimetry and navigation standards are based on this concept. It does not apply when aircraft are flying along specific narrow routes, such as an airport traffic pattern or jet airway.
The Big Sky Theory has been mathematically modeled, using a gas law approach. This implies that collisions of aircraft in free flight should be extremely rare in en-route airspace, whereas operational errors such as violations of formal separation standards should be relatively common. Three critical parameters are the number of flying objects per unit volume, their speed, and their size. Larger, faster objects, flying in a traffic-rich environment are more collision-prone.

http://code7700.com/big_sky_theory.htm

It seems that there are a lot of pilots out there that believe in the "Big Sky Technique." They think the amount of airspace out there is so wide and vast, and that they are so small, that the chances of hitting another aircraft is too small to worry about. And yet history begs to differ.

The Big Sky - Kate Bush

https://www.youtube.com/watch?v=sV7w5TaYjRA&ab_channel=KateB...

    They look down
    At the ground
    Missing
    But I never go in now

    I'm looking at the big sky
    I'm looking at the big sky now
    I'm looking at the big sky
    You never understood me
    You never really tried

Big Sky - Lou Reed

https://www.youtube.com/watch?v=Ug_Z-gu7u44&ab_channel=Naoyo...

    Big sky, big sky holding up the sun
    Big sky, big sky holding up the moon
    Big sky holding down the sea
    But it can't hold us down anymore

    Big sky holding up the stars
    Big sky holding Venus and Mars
    Big sky catch you in a jar
    But it can't hold us down anymore

    Big sky, big enormous place
    Big wind blow all over the place
    Big storm wrecking havoc and waste
    But it can't hold us down anymore

upofadown2• 5 years ago

The problem is that the theory mostly works. "See and avoid" ends up mostly depending on the good odds a lot of the time. Except when it doesn't as in this case.

rkangel• 5 years ago

In free flight, two aircraft can be anywhere in 3D space and collisions are rare.

Around takeoff and landing - there is effectively a 1D track for the approach and the climb-out. It's not quite that simple because different aircraft will have different descent profiles and different angles to the wind, but it's a much smaller 'search space' for collisions.

franciscop• 5 years ago

No deaths nor injuries involved, which I feel like this should be in the headline. I came in expecting to see at least a commercial flight was involved (how does it make to #1 on HN otherwise?) but was very relieved to see it was two small aircrafts with 1 and 2 pilots respectively and everyone survived safely.

OJFord• 5 years ago

I came in expecting to see at least a commercial flight was involved (how does it make to #1 on HN otherwise?)

The Metroliner (one with the fuselage ripped through) is commercial, [0] but apparently carrying cargo only in this case. [1]

Surely a mid-air collision even between two hobby Cessnas say is rare/interesting enough to make it?

[0] https://www.keylimeair.com/

[1] https://www.aopa.org/news-and-media/all-news/2021/may/12/col...

t0mas8811• 5 years ago

The Metroliner isn't really a small (private) aircraft, it's more a commuter type aircraft, 19 seats. But in this case it was only carrying cargo so the place of impact didn't have any people in it.

Another lucky point is that it was at low altitude and at slow speed (preparing to land). Higher up it would have been much more likely to break up due to way higher speed and larger pressure difference between the cabin and outside.

mannykannot7• 5 years ago

Other inches-from-death aspects: there was no-one in the aft of the cabin; the collision missed the pilot; it missed the empennage; it missed the wings; it missed the control cables; and possibly (I'm speculating wildly here) it left the cabin floor intact, without which, I doubt the tail would have stayed on.

benatkin• 5 years ago

If there were two commercial passenger flights involved and it were 300 miles south, it would be life imitating art.

https://en.wikipedia.org/wiki/ABQ_(Breaking_Bad)#Plot

FatalLogic• 5 years ago

It's strange that the planes were supposed to be flying parallel and yet the damage to both planes in the photos suggests a collision at right angles

Remarkable that the Metroliner held together, despite that terrible damage, and they landed it safely

edit: interesting photo of the landing from the Reddit thread linked elsewhere https://imgur.com/gallery/yKPOWR0

t0mas8811• 5 years ago

The Cirrus overshot the centerline of the runway it was supposed to land on. The common way for these situations is for the plane to be on an intercept angle towards the centerline. That's a max 30 degree angle for an instrument approach, but this was a visual approach so it could have been a sharper angle. All it takes to make this mistake in a Cirrus (and other G1000 avionics type small airplanes) is to forget 1 button on the autopilot mode. If it isn't set to capture the final approach track (either GPS or ILS) it will continue straight ahead which in this case means into the side of another airplane.

One thing that makes it more likely is that US air traffic control makes heavy use of visual approaches, and then it's allowed to point two aircraft at collision courses on the same altitude because they can see each other. The European way to do this is to have them intercept at different altitudes so if one overshoots they pass over/under. But it results in lower capacity per runway than the US system.

azalemeth4• 5 years ago

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.

sokoloff13• 5 years ago

If the 1 button on autopilot mode is the red autopilot disconnect, “time to hand-fly” button, I agree with you.

This turn to final (with the unusual additional warning to “do not fly through final”) is a visual maneuver and I’d expect most every pilot to be hand-flying at that point. (My autopilot and navigator is capable to make that intercept, but it’s way more tedious and distracting to program it than to just fly it.)

omegant3• 5 years ago

Looking at the youtube video of the radar with the radio sound that someone posted below, the Cirrus is cleared to runway 17R but he turns to runway 17L. There are 3 possibilities : 1- he mistakes one runway for the other visually, 2- he wrongly thinks he is cleared for the 17L runway 3- or he makes a too wide turn going for the 17R, intruding the 17L area.

The cirrus is the one that makes the mistake.

The 17 runways are quite close laterally (700’) , it may be either way a bad maneuver (overshooting) or chosing the wrong runway.

https://es.flightaware.com/resources/airport/APA/APD/AIRPORT...

The metro was not expecting another traffic in approach for his runway (I understand that they were in different frequencies with different controllers).

During the approach the upper-right side relative angle position in the window of the metro, makes the cirrus hard to spot. I guess he didn’t see the cirrus at all or just barely before the crash.

The cirrus is looking at the runway to his right and the other traffic probably the whole time, the metro is in front of him, so he doesn’t see the Metro till he is on top of him.

Usually with parallel runways, traffics are kept at different altitudes till they are aligned with their runways. This way if they make a mistake, they are separated by 1000’ vertically with the airplane flying parallel.

In this case the cirrus was cleared to visual approach and informed of the cessna he had to follow first. Once he says he has the cessna in sight, he is cleared to visual approach following the cessna. In the same comunication he is informed of the metro flying to the other runway and he replies traffic in sight again.

My guess is that he either has the metro in sight at the beginning and then he forgets about it during the maneuver, or he gives traffic in sight two times.

Thinking that the second part of the message is for the same aircraft (the cessna) he doesn’t even recognize what the controller is telling him about the metro. This is possible if he is too busy flying the maneuver and not paying proper attention to the radio, he hears “cleared for approach” and “traffic” but he mentally don’t really process the information the controller is giving him. A kind of sensory overload.

In airliners we have mandatory TCAS (traffic collision avoidance system) installed that shows you the near traffics in the screen and give you coordinated (between the traffics) automatic avoidance guidance and alarms( one traffic climbs and the other descends or keeps altitude).

In busy airports TCAS maneuver happen relatively often (a handfull of times a year) but nowadays is much harder to have a collision or a close call.

Also when two pilots are in the cockpit (like airliners) it’s easier that one is concentrated in flying and the other in the communications. It’s very common to correct and be corrected all the time during the flight.

It will be interesting to read the official report.

Edit: Kudos to the Metro pilot who was super calmed in the radio while declaring emergency and landing the plane. That is really difficult.

Edit 2: correcting the airport , KAPA (I talked about KDEN initially which has the same runways but with a bigger separation). This does make a difference regarding the mistake.

  Thank you Denvercoder9 for the heads up.

Denvercoder92• 5 years ago

The 17 runways are quite separated laterally so it’s more probable that he was wrongly going for the 17L thinking he was aiming for the correct runway.
https://flttrack.fltplan.com/AirportDiagrams/KDENapt.jpg

This is the diagram for a different airport (Denver International, KDEN). The accident happened at Centennial Airport (KAPA), where the two runways are only separated by about 700 feet.

mannykannot7• 5 years ago

I understand that they were in different frequencies with different controllers.

If that is so, then it seems from the recording that the Metroliner pilot was only informed about the Cessna ahead of him and on approach to 17R, not of the Cirrus.

The Cirrus pilot is told about the Metroliner in an exchange that goes thus:

TWR: "Cirrus 6DJ, traffic you're following just turned right base there ahead and to your right at 6600', Cessna."

6DJ: "I have traffic in sight, 6DJ."

TWR: "Cirrus 6DJ, follow them, runway 17R, cleared to land. Additional traffic north shore, it's a Metroliner for the parallel runway."

6DJ: "Traffic in sight, cleared to land 17R, 6DJ."

Now, does that second "traffic in sight" refer to both aircraft, or only to the Cessna he had just been cleared to follow? It would be unambiguous if he had replied "two in sight", but if, for whatever reason, the mention of the Metroliner (in the same call as the clearance was given) had not registered, the Cirrus pilot would not have been aware that more than one other aircraft needed his attention. And if the Metroliner communication was being conducted on a different frequency, neither pilot would have had any other opportunity to become aware of the other airplane, except by seeing it - and, in addition to the Metroliner pilot presumably being in the left seat, the Cirrus was banked right, turning final, and one might guess its pilot was probably looking at the runways and/or the Cessna ahead.

Putting this together, I suspect the Cirrus pilot never registered the presence of the Metroliner until the collision - and I doubt the Metroliner pilot saw the Cirrus even after the collision, given that he thought he had an engine failure (he might have seen it earlier, when it was heading north on downwind, and assumed it was behind him.)

This does not alter the fact that the Cirrus pilot overshot the 17R approach while turning onto final, and it is this which caused the collision. One other fact, pointed out by several commentators: the Cirrus was travelling at about 160 kts at the time, so any delay in turning final results in being out of position more quickly than in your average small, single-engined airplane.

throwawaygimp2• 5 years ago

@dang "Mid air just north of KAPA- all parties OK" is the more appropriate headline on reddit.

As an aviator my stress levels are only just coming down now from seeing this headline and clicking expecting there to be deaths.

Grustaf2• 5 years ago

What is KAPA and do people know what it means?

mnw21cam3• 5 years ago

It's the code for the particular airport they were about to land at. https://en.wikipedia.org/wiki/Centennial_Airport

t0mas8811• 5 years ago

The ICAO airport code as used for navigation. They're different from the IATA 3 letter codes that most passengers know. US airports start with K, European with E (e.g. EF for Europe-France).

Often for large airports the code is very similar to the IATA code for passengers, e.g. KJFK for JFK and KSFO for San Francisco. But not always, as in EGLL for London Heathrow which is LHR in passenger codes.

tialaramex4• 5 years ago

KAPA is the code for Centennial Airport in Denver. It's likely many US pilots would either know what that is or be trivially able to look it up, non-pilots not so much.

quickthrower2• 5 years ago

Tbf it wouldn’t be the first abbreviation / jargon in a HN title

na852• 5 years ago

I was camping near Whistler a few years ago and heard a bang. Looked up and saw falling debris and bodies. A wing landed not far from our campsite. Turns out a glider (low-wing monoplane) was descending and the tow plane (high wing monoplane) was climbing. They were each in each other's blind spots :(

Glad to see no fatalities here; I'm an aerospace engineer in the field of airworthiness and technical risk management so my work sees a lot of accident reports and flight safety incidents. I can say with certainty these folks (esp. the metroliner crew) are very fortunate.

azalemeth4• 5 years ago

I'm sorry to hear that you witness a mid-air collision -- I hope it wasn't completely fatal. In the UK, all glider pilots wear parachutes and the overwhelming majority have standardised on a collision avoidance system known as FLARM that is "glider friendly" (unlike GNSS) and can differentiate thermalling from colliding.

It's just an internal 16 channel GPS receiver with an external antenna and an altimeter that predicts the flight path and then transmits it - including a unique identifier - as low-power digital burst signals at one-second intervals. Other aircraft also equipped with FLARM receive that, compare it with their own flight path prediction, and also check for collision information with known data on obstacles, including electric power lines, radio masts and cable cars, etc. If a proximity warning is generated to one or more aircraft or obstacles, it bleeps like anything and generates bright LEDs that point in the direction of the threat. The display also gives indication of the threat level, plus the horizontal and vertical bearing to the threat -- and there are three warnings (iirc ~30s, ~15s, ~6s) -- it warns by time and not distance.

I remember the thing going off a few times; it's quite helpful and draws your attention to a region of sky immediately, including behind, above and below you. It's also dirt cheap† and is a battery-powered self-contained box with (I suspect) a microcontroller and glorified smartphone innards inside.

†(by aviation standards)

upofadown2• 5 years ago

Probably this:

* https://www.cbc.ca/news/canada/british-columbia/pemberton-b-...

Whenever there is a collision involving light aircraft the question of anti-collision systems comes up. Unfortunately the powers that be have completely failed to come up with a workable standard for such aircraft. The glider people eventually just gave up on waiting and now use a proprietary system called FLARM which has fairly good adoption. There is more than one system of that type available for light powered aircraft with not very good adoption. Each system is entirely incompatible with each other, including the standardized ones used in heavy commercial aviation.

na852• 5 years ago

Yeah that's the one. I misremembered it as the tow plane instead of a Cessna.

0xFFFE• 5 years ago

Comms between tower and the planes involved. https://www.youtube.com/watch?v=f5tb2dVWJqc

zed88• 5 years ago

Metroliner, often jokingly called as "flying sewer pipe" is one hell of a sturdy plane it seems. Glad to see both parties okay, but this makes me think if BRS should be made standard by FAA on GA planes given the lives saved by the technology so far.

gkanai• 5 years ago

Commercial pilot Juan Browne covers this on his channel:

https://www.youtube.com/watch?v=_Ph7OR6C90w

cmckn2• 5 years ago

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. :)

toast0• 5 years ago

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.

cmckn2• 5 years ago

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).

dillondoyle• 5 years ago

It's really close to the city too.

I'm sure the chances of a collision outside of the airport is absolutely basically zero, but these small planes fly really low over my house and the downtown area all the time. They get pretty low and close for touring over the big buildings for photos and stuff, see photos on reddit all the time..

bartread• 5 years ago

Bloody hell: the state of that Metroliner. Surprised it held together with that amount of damage, and huge kudos to the pilots for getting it on the ground safely.

For such a serious accident this seems about the best possible outcome for the crew of both aircraft. I'm not an expert so I'm not going to comment on root cause or blame here, but simply glad to read that at least everybody survived.

dkarras• 5 years ago

Video of the cirrus chuting down: https://twitter.com/DenverChannel/status/1392560583950561281

A photo of the airborne metroliner with fuselage blown open: https://imgur.com/gallery/yKPOWR0

londons_explore3• 5 years ago

The plane flying missing half the fuselage suggests to me that fuselage was excessively strong (and therefore heavy and expensive).

A tube is only strong when complete. Cut away half the tube and bending resistance probably goes down ~10x.

cesarb• 5 years ago

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 of the cabin.

HPsquared• 5 years ago

The structure would be designed around an adequate fatigue life. I wouldn't be too surprised if fatigue considerations were such that in "normal operations", stresses could well be 10x lower than the ultimate material strength.

EricE4• 5 years ago

Juan Browne of the blancolirio YouTube channel did his usual excellent overview: https://www.youtube.com/watch?v=_Ph7OR6C90w

lujim• 5 years ago

Wow the Cirrus is looking pretty good for how much damage it did to the Metro. Flight surfaces are still there and it's only broken in half of the parachute landing. Guessing it might not have been controllable after the collision.

mdip10• 5 years ago

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 bad weather[1]. He was traveling with his daughter, a friend and, I think, his wife. He died, but his daughter was able to get free and make her way to a nearby farm to call for help. Looking at the plane, the fact that anyone survived at all let alone walked to a nearby house with minor injuries is pretty miraculous.

It's hard to impress upon folks who have never been in a small plane like that just how ... yeah ... how much it feels like you're hanging onto a kite. I have no idea the kinds of structural technologies are involved in the aircraft but I know his plane was made in the 70s and was light enough that he only had a pole which attached to the front landing gear to pull it out of the hangar. 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.

[0] I'll spare the details as I have left many comments in the past about his experiences.

[1] https://aviation-safety.net/wikibase/43894 - "Pilot Error"; I recall my Dad saying "all plane crashes are pilot error"

[2] https://en.wikipedia.org/wiki/Piper_PA-32_Cherokee_Six

qayxc• 5 years ago

The weight is so critical that the 7-seat plane can realistically only seat 4-5 adults.

I think you overlooked an important factor there. The plane was indeed designed to realistically seat 7 adults.

The issue is that in the 50 years since the plane was originally designed, the average weight of adults (in the US) increased by about 18% [0] and the average adult woman today weighs as much as the average adult man in the 1960s.

[0] https://www.newsmax.com/US/average-weight-man-woman-obese/20...

sokoloff13• 5 years ago

I find it very hard to agree that a PA-32 was "designed to realistically seat 7 adults". I don't think they even imagined 6 adults as a typical cabin load, but rather a max of 4 adults and 2 kids and a typical of 2 adults and 2-4 kids. It is one of the more roomy cabins among light singles, but every one of them that I see for listed for sale right now is configured with seating for only 6, which is great for 2 adults and a few kids.

kbutler• 5 years ago

6 * 1.18 = 7.08 people, so that could explain 1 adult.

I think the "some adults, some kids" is more significant - similar to back seats in many small cars - you can put 3 passengers in there, but 3 adults won't be happy.

captainredbeard4• 5 years ago

Wrong - most singles can’t fill the seats and the tanks. This is general aviation 101 folks

mnw21cam3• 5 years ago

There's also the fact that an aircraft like that may be able to carry 7 adults in some conditions. If you're at sea level in cold dry weather[0], then you'll have a lot more performance available than if you're trying to take off from Denver airport on a hot summer day just after a load of rain. There have been (usually light) aircraft that have crashed on takeoff/landing because the pilot didn't take the hot day into account, the minimum flying speed was higher than they expected, and the engine performance was too low.

[0] https://en.wikipedia.org/wiki/Density_altitude

mdip10• 5 years ago

Not so much overlooked as omitted ... I had originally written "average American adults" but I didn't want to distract into the territory of "how bad our diets are in this country".

My Dad almost always flew alone. So much so that when the plane was packed and we were making an approach into the Sandusky, OH airport, we had a sudden "dip" on the way down that everyone noticed (we were headed to Cedar Pointe, so it was preparation, I guess). My Dad explained that he wasn't used to landing with so much weight and hadn't adjusted the trim correctly[0].

[0] If it wasn't abundantly clear, all of my flying experience ended at about age 17, which was a while ago, and I was never a pilot, so to the extent that I get any of this wrong -- that's why :)

AdrianB12• 5 years ago

In aviation load and range are always a compromise, you can fly short distance with a higher load (all passengers) or a longer distance with less passengers. The combined passenger weight and full tanks weight is always more than the Maximum Take Off Weigth (MTOW). For example the small plane that I fly the most has enough fuel capacity to fly around 2000km, but if I will the tanks I need to fly alone, there is no reserve even for a backpack. When I took my brother for a flight around the airstrip I had 20 liters of fuel in the tanks 'cause he is heavy (for an European).

I have a couple of friends that each crash landed at least twice in the past 10-15 years; one was in the hospital once, for the rest of the incidents they simply walked. In two cases it was engine failure, in one a stuck landing gear and the hospital one had an external factor.

sillysaurusx• 5 years ago

Did his wife survive?

osenthuortuh• 5 years ago

The second link is the crash report. There were four occupants and only one fatality, so only he died.

Looks like he tried to land in bad weather, descended before he could see the runway, and clipped some trees. Weather is an alarmingly common cause of accidents in general aviation.

hirundo• 5 years ago

It's hard to impress upon folks who have never been in a small plane like that just how ... yeah ... how much it feels like you're hanging onto a kite.

Years ago I was doing pilot training in a Cessna 152. A coworker of mine was a retired Navy captain and instructor at the TOPGUN program, with hundreds of carrier landings in an F-14. He looked at me like I was crazy. He said those little planes were deathtraps and he'd never go up in one again.

Not long after that I had a lesson that coincided with some turbulence from the nearby coast. The plane janked around by seemingly hundreds of feet in every direction. I was scared (almost literally) shitless, and that was my last lesson. I haven't been in a small plane since.

mistrial9• 5 years ago

thirty foot jump as a passenger in a 4-seater here at 10,000 feet in the mountains - I hear you! :D

mdip10• 5 years ago

I'm glad my Dad's not flying any longer. He was doing very long (multiple stops for re-fueling, flying on some form of breathing tank[0]) trips. He can go on for hours (and we let him) about stories of how he almost didn't make it home due to X or Y[1].

And he joked that every gauge/gadget on the dashboard that didn't come with the plane was there because "if I had it when X happened, X wouldn't have happened" (...or I wouldn't have left the ground knowing the condition existed, or it would have warned me with well enough time to get to safety before I have to be met by emergency vehicles on the tarmac).

Funny enough, he would get a little uncomfortable flying commercial. I'm not sure if he was putting on a show for us kids or if he was serious but he'd say he "didn't like someone else in charge of the plane". My Dad flew GA (alone) a few times a week most weeks, so he was unusually experienced for a small plane pilot.

[0] He had a breathing apparatus that allowed him to fly at higher altitudes in the unpressurized cabin, IIRC, but I'm not a pilot.

[1] Except, when he tells it, he was never in any danger. Doesn't matter if he's hanging an arm out the window trying to manually spin the prop, "it was always under control.". Uh huh.

throwaway0a5e4• 5 years ago

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 paint on a small aircraft.

They make you weigh the paint because they want you to spray on a certain thickness so they say "X oz paint, Y oz thinner/hardener" (or something like that) in order to get your mixture into the right ballpark so it will work with whatever procedure they want you to spray it on with and get the thickness/finish/hardness the OEM wants you to get.

In aviation there's a ton of treating simple systems as black boxes and "do X and exactly X" type maintenance that happens in order to smoothly transfer liability. You paint a cowl the way the OEM says not because you couldn't get an equivalently performing cowl a different way but because you don't want the NTSB coming after you trying to determine if you did it different but right or different but wrong.

The specifications to which general aviation stuff is done isn't really any more exacting than stuff in automotive or heavy industry. The service literature is just more verbose and the service procedures are more tightly defined.

marvin• 5 years ago

I know that glider maintenance procedures in my country call for redoing the center of gravity measurents after painting. Might have been related?

ryandrake• 5 years ago

I'm building an experimental, and we tend to re-do weight and balance after painting. An elaborate paint job can add 30+ pounds and can shift your CG rearward. The regs don't require it, but many builders do it anyway.

mdip10• 5 years ago

Very interesting. I remember thinking it was positively "nuts", but then when you're in the aircraft being slapped around by the breeze, it starts to click.

throwaway330935• 5 years ago

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.

labcomputer• 5 years ago

Well... ok, but you usually still need to weigh and check the balance of the control surfaces after painting to ensure that they aren't going to flutter at less than Vmc (post-paint control surface balancing is often explicitly called out in the maintenance manual).

Painting a plane is one of those times that you often strip everything out anyway, so it's a convenient time to check the weight and balance against the logbook.

officeplant• 5 years ago

The specifications to which general aviation stuff is done isn't really any more exacting than stuff in automotive or heavy industry. The service literature is just more verbose and the service procedures are more tightly defined.

This reminds me of how often I quote weight limits on cars to people and their eyes go wide at how easy it is to exceed the OEM's recommended limits. I'm fairly sure I'm one of the few among my friend groups that has read through every owners manual for the cars/vans I've owned.

ip26• 5 years ago

It's hard to impress upon folks who have never been in a small plane like that just how ... yeah ... how much it feels like you're hanging onto a kite

Went up in a four man single engine chopper once. It had all the reassuring solidity of a bicycle. Never again. I can’t even imagine what the truly tiny ones are like.

lbriner4• 5 years ago

I had a lesson in an Ikarus C42, which although it looks like a "normal" light aircraft is made of kevlar over aluminium and is officially a microlight. It is a 2-seater but the weight is so low that if you are travelling with a passenger, there is a weight limit. I think I worked out that my 6'3" boss was too heavy to fly with an instructor.

It was actually pretty fun but, of course, the weather is everything. I can't imagine how bad it would be in any wind more than about 5 knots but on the day I had my lesson, it was calm and clear.

mdip10• 5 years ago

I did one of those chopper tours over a big city one time in a splurge. Yeah, I hear ya.

I was surprised at how similar the feel is. Your bicycle analogy made me laugh -- spot on. I used to love taking my macho friends up in my dad's plane. There's this moment after take-off where my Dad will comment on "how smooth the air is" ... it's either "perspective" or a pilot joke, I'm not sure, because said "smooth air" is about as bad as reasonable air-turbulence on a jet and the flight is usually marked occasionally by the kind of turbulence that would have the overhead bins tossing luggage onto passengers. I recall a humorous incident where my buddy Tim dropped an F-bomb over a hot mic on the headset when we got smacked sideways.

rubicon33• 5 years ago

There is a similar story in rally car safety. In the 80s and 90s going off the road at high speeds almost certainly meant death or serious injury.

By comparison, there are some horrific crashes today that drivers are walking away from. [1]

[1] https://youtu.be/YpNdoV6xv2s

BashiBazouk• 5 years ago

I once witnessed an airplane crash that everyone survived. I was a preteen hanging around outside the Scotts Valley roller rink with a friend in the early eighties. The roller rink is next to the now defunct airfield. The airfield was lower than the rink by an embankment. We had recently been watching Jaws on Betamax and my most persistent memory is seeing only the tail crossing the field. It reminded me of a shark fin moving through the water, as the embankment was high enough that I could not see the body of the plane. Then bam, the plane hit the embankment right in front of me, caught air then crashed nose down. I think the plane was a Piper but my knowledge of small craft is limited. It was definitely a wing under. My friend ran to get his father and we all ran over to the wreck. My friend's father opened the doors and everyone but the pilot was able to get out by themselves. The pilot had hit his head on something and his face was covered in blood but alive. I found out from press reports later that was the only time I "met" Steve Wozniak.

Edit: just looked it up. The plane was a Beechcraft Bonanza A36TC.

DiggyJohnson• 5 years ago

Thanks for sharing this story. Well structured, great ending.

ZeljkoS• 5 years ago

https://www.cultofmac.com/465778/today-in-apple-history-stev...

dehrmann• 5 years ago

how much it feels like you're hanging onto a kite

The two "small" planes I've ridden in were a Cessna and an L-39. The Cessna felt like a toy, and the L-39 was a serious piece of hardware. Landings were also very different; the Cessna just got tossed around a lot more.

ChrisMarshallNY• 5 years ago

Glad no one was injured or killed. Sounds like the Metroliner pilot did very well.

I really think that we should not have flying cars until we have true autopilot (hands off the wheel, meatbag!). The thought of the "Hey y'all! Lookit this!" knuckleheads that regularly open up, roaring past my house, in three dimensions, is chilling. They are bad enough with just two.

I'll bet that the advent of true driverless tech will also be the advent of illegal aftermarket "mod kits." I can see it now...the "Hold My Beer™" line of manual override modules...

simonswords82• 5 years ago

Reality is that you won't have the type of idiots that roar past your house flying cars/planes or anything of that nature unless it is fully automated because most of them aren't smart enough to pass the tests required to be a pilot.

martyvis• 5 years ago

As always, Juan Browne has great reporting and analysis of this incident https://youtu.be/_Ph7OR6C90w

vertis• 5 years ago

This[0] youtube video has good explanation with the air traffic control audio. The metroliner pilot was cool as a cucumber after being hit.

[0] https://www.youtube.com/watch?v=_Ph7OR6C90w

throw0101a2• 5 years ago

See also VASAviation's recreation of radar plot, which is referenced in the above video:

* https://www.youtube.com/watch?v=f5tb2dVWJqc

HHalvi• 5 years ago

I felt erilly familiar with the details of this accident after reading the details. I dug up my browsing history and realized I watched the ATC exchange of this very collision yesterday not realizing that this had happened the very same day the video was uploaded[0]. Also props to the Cirrus Airframe Parachute System (CAPS), hope this gets implemented in more smaller (or homemade) aircrafts.

[0] https://www.youtube.com/watch?v=f5tb2dVWJqc

wiedehopf• 5 years ago

Exact tracks of both aircraft with timestamps: press K to enable labels https://globe.adsbexchange.com/?icao=a4eabe,a2cee7&lat=39.63...

shockeychap• 5 years ago

The picture of the Metroliner reminds me of the Aloha Airlines incident.

https://en.wikipedia.org/wiki/Aloha_Airlines_Flight_243

It's amazing that the hull can survive in the air for any time with that much torn away.

MobileVet• 5 years ago

Wow, the 'can opener' effect is intense. Insane that the plane held together, so much structural loss.

Reminds me of the Aloha Flight 243. My mom's cousin was the pilot and hearing his first hand account was pretty crazy. Fun fact, he got to be an extra in the made for TV movie of the event.

https://www.thisdayinaviation.com/tag/robert-l-schornstheime...

EricE4• 5 years ago

Juan Browne of the blancolirio YouTube channel did his usual excellent overview: https://www.youtube.com/watch?v=_Ph7OR6C90w

schoen• 5 years ago

I remember seeing some Internet post a couple of decades ago where someone asserted that the goal of ATC was to prevent midair collisions and that U.S. ATC had met this goal perfectly, with no midair collisions between aircraft that were under the control of ATC at the time.

I think the claim was qualified in some way like "collision between civilian flights that were both flying an ATC-assigned clearance at the time". (So some kinds of flights and some kinds of airspace don't require ATC clearance, and if one of them were involved in a collision, it wouldn't be ATC's responsibility, in some sense.)

My question at the moment is: is this claim plausible if you qualify or restrict it enough? Do you have to tack on additional conditions?

Is there any useful sense in which this collision was a first for U.S. aviation history?

mlac• 5 years ago

"The Cirrus descended through 6400 feet about 3nm north of the threshold of runway 17R, but overshot the centerlines of both runways 17R and 17L"

It looks like the Cirrus wasn't flying to what the ATC cleared...

FabHK• 5 years ago

I wonder how many mid air collisions we would expect to see if see-and-avoid where entirely ineffectual, or pilots would not look outside ever except to land. I have the impression the accident numbers would not be much worse than they are.

In other words, my hypothesis is that the fact that there are few mid-airs is owed to ATC, technology (TCAS, TAS) and “big sky”, rather than vigilant pilots.

ericpauley• 5 years ago

Agreed. It can be hard to spot traffic even if you know where the other plane is! With this in mind ADS-B/TIS-B seems like such an essential tool for GA pilots.

Midair Collision over Denver

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