Comment by aeternum | Hacker News Reader

Comment by aeternum | Hacker News Reader

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Excellent points, it's really these other aspects that get pilots into trouble.

For example it's crazy that most pilots are still taught to calculate W&B using printed charts and approximate takeoff performance.

I think you could save more general aviation lives with a fairly minimal system.

A gas gauge sensor that calculates whether you have enough fuel to get to your destination + reserve. Avionics where you input your personal minimums like crosswinds and weather and it warns you if you're about to accept a landing or flight-plan that violates those. Encode that data and send it to ATC via transponder so valuable comm bandwidth is not lost asking for fuel status when emergencies occur.

A gear down warning. It's ridiculous that we still have so many belly landings and consider it a "good" to rely on training and human memory to prevent them. How much cheaper would complex airplanes be if we didn't have the crazy insurance rates due to this?

Angle-of-attack and spin warnings. It's ridiculous that even $1mil+ Cirrus planes can't detect when you're too slow in a base to final turn and sound a warning before you spin. We have the technology, it's foolish to depend on a decades old stall horn!

A system that parses all the hundreds of notams and filters out the important ones.

> For example it's crazy that most pilots are still taught to calculate W&B using printed charts and approximate takeoff performance.

We're taught that so we know what we're doing. Then we open our iPhone app (EFB or electronic flightbag) and do it there. In fact, part of the reason we do it there is because most of them phone home to their maker and log that we did it. So if there's an accident people can know "well they did their W&B"

> the rest of the things

Regulations have made aviation so expensive that it's ridiculous. A lot of airplanes flying today are flying with their same avionics from 60 years ago because upgrading is expensive. To get the gas calculation you mention would require a certified GPS (on the low end from Garmin that's $6,000) and an engine monitor ($5,500 from Garmin), plus installation costs of another few thousand dollars.

Most planes have a gear down warning (ie, 3 indicator lights) but their original "bitching betty" is hard to hear because we now wear ear protection when we fly and have noise cancelling headphones. You probably can't even integrate that with a new Garmin system because they've gone full encrypted CANBUS to lock out integrations.

re: spin warnings - not sure what to tell you there. Stall speed is based on weight and configuration (flaps) and 99% of GA planes have no idea what they weigh or if their flaps are deployed.

But again, it's not that we can't do those things, it's just that they're completely cost prohibitive. Getting anything certified today is a flippin' nightmare and at too high of a cost to ever break even.

Stall speed is a misnomer.

Stalls occur due to exceeding the critical angle of attack and can happen at ANY speed.

I think that was his point. To calculate if you are going to stall in a final, you need to know your weight and flap setting to see if you will exceed the critical angle of attack when doing the turn, exactly because the speed isn’t constant.

No, you just need an angle of attack sensor. These are increasingly available for small GA planes.

stall AoA depends on flaps though?

Yes, and some sensors do take flaps position into account (or you compromise and have it display the AoA with a typical approach setting).

You need an AoA sensor to see if you are currently stalling or are just about to stall. To predict if you will stall at a specific point in your approach before you’re there, you need to know your weight, too.

Whoever is downvoting this: Stop. It's the key point here. Planes don't need to know their weight to produce a stall warning; AoA is a great metric, and GA planes not having an indicator or warning based on it is astonishing.

I thought the point was predicting a stall by knowing the approach speed will be so low that you will stall, not detecting a stall just before it happens

You can't control the weather, if there's a micro burst during landing you are in trouble.

GA planes have a stall warning horn (based on AoA). They just generally don't have a AoA indicator (though that might be a good idea indeed), relying on indicated airspeed instead, which (for given airplane mass) has a one-to-one [1] mapping to AoA in unaccelerated flight. That's why the concept of stall speed exists.

That is the case since, in unaccelerated flight, we need weight == lift, so

   W := m g == L := 1/2 rho v^2 c_L S

with m = mass, g = earth gravitational acceleration, 1/2 rho v^2 = fluid dynamic pressure which is measured by the pitot tube and displayed as indicated airspeed (well, a function of it), c_L = the coefficient of lift, and S = wing area.

Now, weight is constant (for given airplane mass, in unaccelerated flight), and so is the wing area. The coefficient of lift depends on the AoA, and dynamic pressure has a monotonic one-to-one relationship to IAS. Thus you have the relationship between IAS and AoA.

[1] Unless you get to "the back of the power curve" (the coefficient of lift increases with AoA, then decreases again, until it drops off in a stall). Let's not go there.

it's a misnomer but airspeed is life. we're not talking about people stalling during air combat or aerobatics, we're talking about doing it in the pattern. simply keeping your speed up and knowing the speed you will stall at based on bank angle should be enough.

> But again, it's not that we can't do those things, it's just that they're completely cost prohibitive.

Isn’t this what the OP is referring to when he says the current market can’t support the necessary innovation? As I understand it the idea here is to expand the market and spread certification costs out over more planes.

I don't think he can get the required certifications and charge a reasonable price for this plane. There are not enough people interested in a personal airplane at any price to support the costs to bring a new one in the air. You can rebuild all current airplane's (most built before 1980) for much less than the costs to certify a modern replacement, and only then can you start asking what it costs to build that replacement. Which is why we rebuild old airplanes all the time - it is wouldn't pass modern regulations but since it already exists it is certified.

There's an interesting dynamic here--we (the industry today) are more okay with flying rickety airplanes from the 70s before flying something built with more modern engineering and production techniques.

> As I understand it the idea here is to expand the market and spread certification costs out over more planes.

exactly.

> There are not enough people interested in a personal airplane at any price to support the costs to bring a new one in the air.

our thesis is that this isn't true. we've seen glimpses of this in the past 10 years that haven't been successful, but have shown that there is a wave of people who would get into GA if it were safer and more affordable. our mission to make it so, and the Airhart Sling is just the first step

I'm not wishing you bad luck, but I remain pessimistic about your ability to get something certified and charge a reasonable price.

> There's an interesting dynamic here--we (the industry today) are more okay with flying rickety airplanes from the 70s before flying something built with more modern engineering and production techniques.

Any insights on why that is? My gut feeling is that it’s some combination of cost (there’s still a huge glut of old and cheap planes that basically work fine) and skepticism towards new, less proven models and technologies (i.e. the perception of Cirrus changed very slowly over a decade plus to where now the chute is generally accepted to be a good thing to have).

I think there's definitely a "tried and true" and "if it aint broke don't fix it" mentality. Combine that with the fear of trying something new in the face of the FAA and regulatory barrier, many will say it's better to just take the risk on older stuff than make something new and better

While some base to final stall accidents are as simple as you make it sound a good chunk of them happen when you try to come OUT of the turn at an already slow speed increasing the angle of attack on one wing alone. The stall and subsequent spin catches the pilot entirely surprised unaware of why they’re even stalling and with very little escape bandwidth.

The FAA has been trying for better angle of attack instrumentation but what I described above isn’t an easy fix with technology.

When you talk to pilots who inadvertently stall spin and lived to tell the tale most of them will tell you they didn’t even recognize that they were in a stall. That’s where the problem starts.

Right but I don't know of any GA stall/spin warning system that takes into account pilot input. Even simple sensors are lacking, for example accelerometers are nearly free yet GA planes give you no warning that you're in a skid.

Similarly given yoke input, bank angle and speed you could warn of an impending stall well before it actually happens with a few position encoder sensors. As you point out, the current system relies on pilots recognizing a stall which is a foolish thing to rely on and almost all GA stall warning sensors are only on one of the wings and require actual airflow disruption to work. In many cases that is already too late or the other wing could stall first. The calculation doesn't even have to be perfect since most pilots want plenty of margin of safety on a base to final turn. I'd much rather have a false alarm + go-around than an inadvertent spin.

The collision thing is also ridiculously irrational. The FAA requires drones over half a pound to continually transmit their location yet somehow considers it sufficiently safe for planes to fly without a radio nor transponder around most of the airports in the US relying only on pilots looking out the window.

It's just disappointing that the vast majority of GA accidents could be completely avoided with slightly better avionics.

Civilian drones are fairly new. There are century old GA aircraft still flying around. I'm sure the FAA would love to require them all to carry radios and transponders but it's technically and politically difficult to impose new requirements on old certified aircraft. Some owners can barely afford to fly as it is so they'll resist any new mandates.

This is a common argument but makes little sense because the accident and loss rates of GA is so incredibly high. The cost of an ADS-B receiver for example is only $200. Full transceivers are a few thousand.

Aircraft owners are already paying well over that as insurance rates yearly because of all the accidents, so total cost to fly would likely decrease by mandating things that actually move the needle on safety, especially ADS-B and fuel alerts.

> the vast majority of GA accidents could be completely avoided with slightly better avionics.

Reading accident reports or the annual summary McSpadden Report (previously called the Nall Report), I get a different view: if pilots would keep fuel in the airplane and flowing to the engine(s), not fly into weather beyond the capability of the airplane and crew, and divert or not takeoff at the onset of signs that an aircraft is not airworthy, would reduce serious accidents by half or more. Better avionics has relatively little to do with that (other than the proper use of a fuel totalizer or better).

Complacency kills more pilots than weak avionics.

Most cars give you significant warnings that you're about to run out of gas and as a result very few people do.

Improved avionics could warn you that you're flying into a storm or that the airplane is not airworthy or that you are converging with other traffic.

Complacency kills because it sneaks up on pilots, but it doesn't have to be that way. We should not accept that the FAA's answer is an IMSAFE checklist. Pilots should not have to die simply because they didn't realize they were feeling slightly stressed or emotional prior to takeoff and forgot to check a single one of the 40+ items on the preflight/runup/takeoff checklists.

Of course good pilots should check it all anyway but just as NHTSA requires safety warnings for cars, we could save many more lives if we required low fuel warnings, terrain warnings, gear warnings, speed warnings, etc. in aircraft avionics.

I agree there is room for improvement and smarter airplane equipment is undoubtedly part of that.

I do not believe that “slightly better avionics will completely avoid the vast majority of GA accidents.”

>Most cars give you significant warnings that you're about to run out of gas and as a result very few people do.

You will see accident reports where the problem is that the pilot just completely failed to put enough fuel in the airplane and then flew it until it ran out; but that's not the typical thing.

What's much more common is that the pilot takes off with what seems like ample fuel, gets halfway there, discovers weather that is worse than expected, has to fly lower than planned, burns a lot more fuel as a result, discovers that they will have to refuel, can't find an airport with good weather at which to land, and ends up flying a graveyard spiral into a fatal crash caused by disorientation in conditions for which they are not trained.

The majority of accidents are traceable to poor planning or decision-making once airborne; and I tend to agree with the other poster that improved avionics are not going to make a really big difference.

Improved avionics should help with all of those aspects:

1) Continually recalculate fuel remaining upon landing at destination based on ground speed and burn rate. Warn if getting anywhere near reserves.

2) Show nearest filtered airports (those with runways that satisfy both airplane and pilot requirements (max x-wind). If IFR, further filter by approach preferences and if available current wx data against approach minimums.

I agree with you that what you describe is a common accident scenario but imagine a PPL could just hit a single button if they inadvertently enter IMC and the avionics provides a route and vnav profile to make it safely to an airport with low minimums? The most difficult part of flying IFR is that it takes a ridiculous number of button presses on most systems to accomplish that all while trying to also keep the plane straight and level.

I'd be fairly surprised if most (say 75+%) GA airplanes regularly used for purposeful travel lack a moving map GPS and fuel-flow enabled engine monitor. (The moving map is probably well over 90% and it's the engine monitor equipment rate that may drag it down.)

In every airplane I've been in that is equipped with both of those, the pilot has access to both projected* fuel remaining at destination (in minutes and in gallons), has an ability to get a warning if configurable thresholds are violated, and with just the moving map GPS to have a filtered (usually by minimum length, paved vs soft, and sometimes lit vs unlit) and to have the nearest ("NRST") button present a list of airports, distance, and direction with a single button push.

There are things that could be done to make it better, but I wonder if you're imagining a lower/lesser level of equipment in typical GA traveling aircraft than is currently the case. (To the extent that equipment is already installed that provides 90-95% of the proposed functionality, providing that last 5-10% probably isn't going to be the missing piece of the puzzle.)

* Based on current groundspeed.

People run out of gas all the time (there are a lot of drivers, probably most never will in their lifetime, but that still leaves a lot that do). However in a car running out of gas is much easier to recover from - most of the time you can safely and easially coast to the side of the road. In an airplane there rarely is an airport nearby to coast into, so you end up looking for a place that might or might not be a good option - roads have power lines that you won't see until it is too late, fields sometimes have large holes (wet spots) that if you into at landing speed will flip the plane.

Low fuel warnings wouldn't really help in an airplane - from what I can tell most who run out of fuel know they are low for a while but are unable to get someplace to fill up.

If you’re about to run out of gas in a car it’s usually not a big deal - you find the nearest gas station and go there. Usually. There are exceptions like driving 100 miles of desert with no gas stations in sight and forgetting to put enough gas in. If that was the common driving scenario I’d bet way more people would run out of gas, and no warning light will help.

Flying a plane is often sort of like that - planning mistakes tend to become problems with large time windows where a warning light is way too late to affect the outcome. Flying into a long narrow canyon is another example where your fate can be sealed minutes before you actually fly into the mountain.

All of this can and should be made better with technology, but a lot of flying hazards are more complex than “warn the user about something happening in the next few seconds”.

Why does the warning have to happen in the next few seconds? Electric vehicles warn you at the start of your trip if you won't make it to your destination.

I used to have a super old handheld aviation GPS that would warn me something like 15 minutes out if my flight path was going to intersect either with terrain or B/C/D airspace. I guess foreflight somewhat recently added the feature but it still defaults to something like 3 min.

> Electric vehicles warn you at the start of your trip if you won't make it to your destination.

Road navigation is relatively simple and even then there are unexpected road closures and stuff like that. If running out of gas was an emergency in a car you’d never rely on this warning alone, you’d do more careful planning and fuel monitoring. And then cars don’t have to deal with unexpected headwinds, weather (maybe occasionally), closed runways, the list goes on. It’s just a much harder forecasting problem.

> GA planes give you no warning that you're in a skid.

"The ball" will show you that you're in a skid.

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

That makes a lot of sense, interested to learn more about this, any statistics you’re aware of on this topic?

I don’t have those I’m sorry. Not that much into it.

If you need a better understanding look for a video of a pilot I think in South Africa or Australia who took a cameraman and his wife and stalled shortly after takeoff.

It’s interesting to see how many warning signs throughout the whole video are glaring at him yet he keeps flying all the way into the crash. What’s also interesting is that that’s it. Just warning signs but if you really try to put yourself in his shoes it’s entirely hard to accept the warnings as everything on surface level understanding seems normal, controlled and flat. Very very very flat.

I think the biggest problem with real life stalls as compared to training world ones are that they are either more benign or entirely out of left field and believing you’re about to go into one doesn’t even begin to enter the pilot’s mind let alone correct recovery techniques.

Thanks, by the way if that’s the same video I’m thinking of the problem there was gross incompetence - he tied the door wide open to the wing strut!

Another piece of statistics I recently learned is that most stalls occur on departure or go arounds, and classic base to final are relatively rare. Maybe those have been successfully trained out.

The FAA also has the NTSB investigate every crash and accident, and if it was something as simple as "change the airport patterns to be larger and faster" or "make more airports straight in" it would have already been done.

Fancier aeronautics has a way of letting the plane get ahead of the pilot even faster.

As much as I am excited about Airhart, I would be way more excited for all of these items than I would be for the fly by wire bit. These would be more likely keep me and my wallet in one piece and lower the cost of aviation. Unfortunately they're not terrifically sexy or super lucrative problems.

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