Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Enroute Airbus A380 wake flips Challenger business jet upside down

flightservicebureau.org

Post reply on HN
Print view View original

341–350 of 376 posts

Re: Enroute Airbus A380 wake flips Challenger business jet upside down

#341

Post by mikeash »

gingerbread-man wrote: post #285
mikeash wrote: post #272

Earlier quoted context omitted.

Larger airplanes are also much more capable (better instruments, things like anti-icing systems, ability to fly above weather), far better maintained on average, fly into better airports, have better flight planning resources, and more. Note that when looking at airline safety, you'll get misleading numbers if you go back too far. Safety has improved remarkably in the past couple of decades. In the 80s and 90s, a cou…

The challenge with measuring the safety of general aviation is that it is much more behavior-dependant. All of the US airlines use the same standards for deciding when to fly/ not fly for weather, have similar maintenance programs, training requirements, etc... When it comes to private air travel, it's all up to the pilot and the insurance company.

I imagine GA follows something like a Pareto distribution, with 10% of the pilots involved in 90% of the incidents. That 10% would get retrained or weeded out in the airlines, and the rest get much more consistency on all the rest of the stuff you mention.

So yeah, there really isn't any one "the safety of general aviation." It's a huge spectrum.

Another challenge is reporting. The FAA knows exactly how many flights and how many hours the airlines did last year, but GA activity is much harder to gauge. It's hard to figure out what safety looks like when you don't have a good figure for the denominator.

Re: Enroute Airbus A380 wake flips Challenger business jet upside down

#342

Post by M_Grey »

lathiat wrote: post #164
wfunction wrote: post #71

Earlier quoted context omitted.

Even half a minute minute is a hell of a lot of time and overwhelmingly better than no notice. Currently airplanes sometimes only turn on the sign after the turbulence has already started. Also, it's not like they never have no idea which airplanes are around them until they visually see the airplane. They could turn on the sign earlier if they know earlier.

In my experience (particularly on Emirates) they generally turn the seatbelt sign on before the turbulence because they can generally predict it on radar. It is a little annoying when you have 20-30 minute seatbelt periods with barely any actual turbulence but there you go.

This is true for any airline, but there is something (like the story in this case) called "CAT" or Clear Air Turbulence.

Re: Enroute Airbus A380 wake flips Challenger business jet upside down

#343

Post by Zak »

jonsen wrote: post #148
cyberferret wrote: post #137

Earlier quoted context omitted.

And as I have mentioned elsewhere on here - I have flown inverted a few times, and to do so take a tremendous amount of forward pressure on the control stick to even try and attempt to hold altitude while inverted, in order to counteract the wings natural (slight) positive AoA and the tendency for the wing to move towards it upper surface. In fact, most of the aircraft I have flown would not be able to sustain invert…

> I have flown inverted a few times, and to do so take a tremendous amount of forward pressure on the control stick to even try and attempt to hold altitude while inverted, in order to counteract the wings natural (slight) positive AoA and the tendency for the wing to move towards it upper surface. I don't think that is right. The tail wing has a different angle of attack than the main wing. On the order of one degre…

The horizontal stabilizer of most aircraft has a negative angle of attack and produces downforce, not lift in straight and level flight. This allows the center of gravity to be forward of the wing's center of lift by moving the overall center of lift forward. The result is a tendency to pitch down if airspeed decreases without other control inputs, countering the reduced airspeed.

Flying inverted in a relatively stable aircraft requires a lot of forward pressure because for the inverted aircraft's wing to have a positive angle of attack, the horizontal stabilizer has an even larger positive angle of attack. The pilot must counter this with the elevator to establish a stable ratio of lift to downforce.

Re: Enroute Airbus A380 wake flips Challenger business jet upside down

#344

Post by camperman »

ajross wrote: post #306
camperman wrote: post #297

Earlier quoted context omitted.

Nonsense. See here: https://www.av8n.com/how/htm/airfoils.html#sec-fluid

Yeah, that site is indeed one of the worst offenders. Try a fluid dynamics textbook. I genuinely don't think you understand what I'm saying. Air isn't magic fairy dust that pushes on airfoils from a distance. Pressure is impact.

If you hit a slice shot in tennis, the ball will travel considerably further because the backspin produces circulation which generates lift. If air was a bunch of bullets, the effect wouldn't happen at all. If you raise a spoiler on a Grob's wing, its lift-producing capabilities drop considerably because the spoiler interferes with the circulation. If air was a bunch of bullets, a spoiler wouldn't do anything.

> Air isn't magic fairy dust that pushes on airfoils from a distance.

No. Like I said, it's a fluid that has pressure and velocity everywhere. At low enough Reynolds numbers, like for model gliders, you can even get away with treating it as a non-compressible fluid with decent results.

> Pressure is impact.

And contact between two objects is really about Pauli exclusion surfaces at the atomic level. So what?

Re: Enroute Airbus A380 wake flips Challenger business jet upside down

#345

Post by scrumper »

gingerbread-man wrote: post #237
burkemw3 wrote: post #226

Earlier quoted context omitted.

I'm interested in hearing the intracacies!

There really aren't any good trick to it-- it's just a matter of finding a good vantage point and watching each driver go by. You're supposed to note the color of the belt (black) and the color of the driver's shirt before pulling the car over. As you'd imagine, fatigue comes quickly-- I never did more than an hour or two at a time. (I still have no idea how the highway patrollmen can it all day, every day without lo…

Aha that last point might explain the recent plea bargain I had: a ticket for crossing a double yellow line (points, substantial fine) and I was offered a small fine and no points if I took a seatbelt violation. So did everyone else in court. So I guess that helped the PD get some traffic safety funds?

Re: Enroute Airbus A380 wake flips Challenger business jet upside down

#346

Post by komali2 »

pm wrote: post #190
tluyben2 wrote: post #127

Earlier quoted context omitted.

Anecdotal but I notice in my circles only less financially well off people endulge in quackery. The latest is that you do not need treatment for anything if you do enough marijuana and reiki (not to mention a lot of poor people burn their last money on reiki training....) especially not doing chemo when they sbould is hard to witness.

I can't say I know anyone who's indulged reiki, but I've got a lot of flak from my brother telling me that cannabis cures cancer, when I told him that I was doing chemoradiotherapy for my Stage 3 rectal cancer. Today I've finished a cycle of six weeks of treatment, and while I'm extremely tired, the signs are good that it's in remission. If I'm lucky, I'll have a full pathological response, i.e., it's gone. Despite t…

I'm not sure about cannabis curing cancer, but there's ample research to support that it can help tremendously with the side effects of chemo. Basically, it can make life more comfortable while you go through treatment.

Re: Enroute Airbus A380 wake flips Challenger business jet upside down

#347

Post by antisthenes »

gingerbread-man wrote: post #216
sundvor wrote: post #62

Earlier quoted context omitted.

True.I would think this would be more of a problem for people from US states where wearing a seatbelt is not mandatory. In other parts of the world (with more sense) such as Europe, Australia, we're conditioned to always using it due to strict enforcement and as such it's not such a novelty.

Speaking as someone who has actually done seatbelt enforcement, (I worked as a cop for a year after college before getting into software development,) catching people who aren't wearing their seatbelts is really, really hard. Each seatbelt ticket written probably takes ~30 minutes of time for the issuing officer.

Computer vision and machine learning to the rescue?

Re: Enroute Airbus A380 wake flips Challenger business jet upside down

#348

Post by jkchu »

hueving wrote: post #106
M_Grey wrote: post #63

Earlier quoted context omitted.

When I was in single digits, my mother and I were coming home from an international flight and the plane was struck by lightning. We lost a bit of altitude (felt like a TON of altitude subjectively), and yeah... it was a damned good thing we'd all been told to keep those seatbelts on. It was literally the difference between seconds of terror, and someone being seriously injured.

What likely happened is that you hit a wind shear at the same time as being struck by lightning. Planes are struck by lightning frequently without passengers even realizing.

I flew into Dallas during a storm once, plane was struck by lightning many, many times. It was pretty spooky, but that was all. The lightning simply passes through the exterior of the plane. However if there is a gap in the exterior, then damage could occur.

https://www.scientificamerican.com/article/what-happens-when...

Re: Enroute Airbus A380 wake flips Challenger business jet upside down

#349

Post by gingerbread-man »

macintux wrote: post #307
gingerbread-man wrote: post #237

Earlier quoted context omitted.

There really aren't any good trick to it-- it's just a matter of finding a good vantage point and watching each driver go by. You're supposed to note the color of the belt (black) and the color of the driver's shirt before pulling the car over. As you'd imagine, fatigue comes quickly-- I never did more than an hour or two at a time. (I still have no idea how the highway patrollmen can it all day, every day without lo…

I'm surprised. At least here in Indiana, as best as I recall, drivers cannot be pulled over for seatbelt violations, only if some other offense occurs.

It varies based on state law. The federal DOT can't pass its own traffic laws or regulations for constitutional reasons, so they incentivise states to implement what they think is a good idea by offering them financial incentives. The best example of this is the 21-year-old drinking age. (They threatened to cut off all highway funding for states that didn't raise it from 18 to 21.)

Pretty much every traffic officer I know could find at least 5 reasons to pull over any car, no matter how scrupulous the driver.

Re: Enroute Airbus A380 wake flips Challenger business jet upside down

#350

Post by gingerbread-man »

scrumper wrote: post #345
gingerbread-man wrote: post #237

Earlier quoted context omitted.

There really aren't any good trick to it-- it's just a matter of finding a good vantage point and watching each driver go by. You're supposed to note the color of the belt (black) and the color of the driver's shirt before pulling the car over. As you'd imagine, fatigue comes quickly-- I never did more than an hour or two at a time. (I still have no idea how the highway patrollmen can it all day, every day without lo…

Aha that last point might explain the recent plea bargain I had: a ticket for crossing a double yellow line (points, substantial fine) and I was offered a small fine and no points if I took a seatbelt violation. So did everyone else in court. So I guess that helped the PD get some traffic safety funds?

It's possible, but in my experience the stats NHTSA looked at were compiled by the police department, not the court. (They cared about how many tickets we wrote, not how many convictions were obtained.)

A more likely explanation is the severe underfunding and understaffing of prosecutor's offices and state court systems. Most prosecuting attorneys are responsible for carrying hundreds of cases at a time-- they have no choice but to prioritize, aggressively.

Post reply on HN