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Comment by throw0101a | Hacker News Reader

There are a lot of old Cessna-type planes out there in the US (and to a certain extent Canada) that act as the backbone of the pilot training pipeline: what will it take to update all of those? (And a whole bunch are owned 'for fun'.)

I guess after people had to pay to meet the FAA's ADS-B mandate, this is another equipment update that will need to dealt with.

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A lot of those are also being retrofitted with newer gauges... Garmin has a whole series of products that is basically "take your six-pack and make it digital!" sort of stuff. I think your ADS-B analogy is spot on -- I'd imagine this go somewhere in the same way as that.

The direction indicator is gyro based rather than magnetic so for most GA it would probably be enough to just learn the offset for the area you are flying and add that when you set/check the DI.

For VFR flying it hardly matters anyway

The direction indicator is not a gyrocompass, though – it will eventually drift unless it's periodically adjusted.

Sure but in small GA planes you're not likely to be travelling so far that the magnetic declination is significantly different so just keep it in mind each time you reset the DI. Or if you are travelling long distance you could make a note of it along your planned route, or your GPS app could let you know.

My point was that this shouldn't require any instrument upgrades to the GA fleet

Also, the compass used for calibrating the gyro is pretty small and wobbly. I really doubt you'd be even be able to read that minor difference off it.

Edit: Just read here that in the pacific Northwest of the US there is a 20 degree deviation! I had no idea. Where I flew it was a degree at most.

...a Raspberry PI, some COTS sensors, a USB power bank and an old iPad:

http://stratux.me/

(or: less than the cost of a usual 100h overhaul ;-)

source: PPL applicant and fellow hacker

Doesn't that need to be FAA certified to be relied upon in an aircraft? That's generally what adds all the expense between "homebrew" and "commercial", isn't it?

It needs to be certified to be permanently installed in a non-experimental aircraft, or to be relied upon for IFR use, but for VFR use powered from a cigarette lighter and suction cuped to the window, you can do whatever you want.

It's classed as "pilot carry-on" equipment and doesn't need to be certified. Only stuff permanently installed gets that treatment.

Just as I don't have to have my pen and pad (or indeed my iPad) certified either :)

I wonder how many aviate with a big-ass “portable” lithium ion battery to power it all instead of paying $100 for a flight-certified cigarette lighter receptacle:

https://www.aircraftspruce.com/catalog/elpages/cigrecept.php

I have a pair of 13aH Anker batteries I use, rather than dealing with the lighter plug. The electrical isolation is a feature.

uh, no.

Homebrew hacking is one thing on your dining room table, or for basic home automation, or whatever.

Homebrew hacking in an airplane sounds like an awful idea.

why?

homebrew solutions generally don't have the excessive redundancy that keeps planes from crashing.

You mainly see "excessive redundancy" in larger cargo, passenger, and military aircraft. Small general aviation airplanes don't have as many redundant systems as you'd think. There is neither the space or weight budget. For safety, they mainly rely on well engineered systems, frequent inspections, required maintenance and updates, and failsafe design, such as the ability to pilot the plane as a glider if the engine cuts out.

Not all systems are safety-critical though. Most hackers probably wouldn't mess with control surfaces, engine control, and instruments, and would err on the side of safety too. But planes don't immediately drop from the sky just because their radio is off or their navigation systems have a hickup.

Homebrew hacking of ultralight airplanes (including homebuilt planes) is common here in Czechia, legislation is much less restrictive than for homebrew hacking of cars.

> Homebrew hacking in an airplane sounds like an awful idea.

These are not for commercial aviation. The only area where homebrew can "fly" is experimental airplanes. And in that application it kinda makes sense. Many of those airplanes were made in someones garage themselves, so why stop there and why not make the instruments yourself too?

Uh, yes.

There is a whole aviation subculture of experimental aircraft designers, builders, and hobbyist engineers. There are limitations of course (mostly to do with passenger safety) but the FAA grants a surprising amount of leeway once an aircraft is granted the "experimental" label.

> this is another equipment update that will need to dealt with.

Even in planes with only 'steam' gauges the changes are minor — you won't need any new equipment.

Currently: direction indicator is set to magnetic. When planning a flight you take true headings from charts and have to convert them all to magnetic. You then fly magnetic headings.

After the changeover: direction indicator is set to true. No need to convert headings when planning a flight. You fly true headings, and the only conversion you need to make is when setting the DI from the compass.

(If you don't have a DI you can still pre-convert all your headings to magnetic and fly those. You'll need to mentally convert runways headings etc. though.)

It drifts considerably over time so you'd have to set it to true periodically which on the ground during start up is fine but not in the air, having to determine magnetic variation at your current location.

magnetic variation doesn't change all that quickly at 100 knots, and charts provide the variation. I don't really see it being a much bigger workload, and I imagine that if this change does occur chart plotters like Foreflight will start displaying the current variation very prominently for convenience (it's already pretty easy to pull up). I can also imagine people starting to sell retrofit bug rings for heading indicators that let you set the variation in for convenient setting.

But in general most pilots of slow aircraft probably already know the approx. variation around their area by memory, most pilots of fast aircraft will have instruments that do it for them.

I don't have a pilot license, but from what I recall of limited training, don't you do most of your training based on Heading Indicator? You adjust it at beginning, which can easily be switched to whatever heading/offset of the runway is (true or magnetic); then reset it to compass as needed on level flight - which is rare during short training flights, and could be adjusted to appropriate offset.

So I don't think training itself will be a problem.

Once you have actual flights in those aircraft though, I imagine it'll be a bigger kerfuffle for pilots.

a lot of smaller planes have only magnetic compass, no gyro-based heading indicator

Not true, even the lowly rental C172 with 3 shades of paint and carpet at any raggedy flight school will have a gyro based indicator.

Magnetic course calculation is only taught at the initial license level and to instructors. Anyone else is flying by GPS or radio-based nav.

OK but the vacuum gyro in said raggedy-ass 172 needs setting against something as part of the checklist (and quite possibly in flight), which today is the magnetic compass.

Yeah, but this is really only applicable to VFR-only airplanes (mostly trainers). I doubt there are many people really traveling in airplanes without any sort of precision nav equipment.

Practically, it doesn't matter which direction the gyro points as long as you are receiving a VOR signal or GPS signal on a VFR flight.

And yeah, a lot in flight. By definition those gyros are gonna be old, and they cost more to overhaul than they're worth so people who are too cheap to go buy an electronic replacement replace used for used off of eBay or the local radio shop's junk shelf. They're not gonna be reliable, at all.

But, for VFR purposes it doesn't matter and for IFR purposes you shouldn't be flying such an airplane with such equipment IFR anyway, so...

Right. And then you'd have to apply a correction (which might change a tiny bit over several hundreds of miles flown, or over the years).

But no need to change anything in the aircraft, as far as I can tell. Just planning and procedures.

Great, C172 counts as "more expensive" option here, training will go on raggedy ass C150 recovered from a crash, be happy if you get turn indicator.

That in the US?

Here in Europe both are needed to be kept to pretty high standards. You can do basically nothing yourself anymore.

No, in Europe.

There's surprising amount of what is actually allowed and what is believed to be allowed often doesn't match :)

Most GA planes in Poland would be VFR only, I bet.

They just said "a lot of". There are a lot of pre-1950 planes out there flying without a 6 pack to be heard of. Good ole stick and rudder flying. No gyro instruments needed... just altimeter, airspeed, tach, fuel, and the horizon.

NBC: Harrison Ford Lands On Taxiway

https://www.avweb.com/news/nbc-harrison-ford-lands-on-taxiwa...

While it’s legal under part 91 to have only a magnetic compass, a vaccine powered gyro DI (or solid state equivalent) can be found in the majority of the GA fleet. The aircraft without a DI are typically ones with bush flying or acrobatic missions, where pilots don’t spend much time looking at their instruments for navigation anyway.

It took me a while to realize that you meant vacuum powered. :)

Q up there made a Freudian slip :-)

In my country (Romania) all of the small planes I flied (about a dozen) had just 2 or 3 magnetic compasses. These planes are allowed to fly only on visual orientation conditions (weird local laws), so navigation is not a real concern.

I think any requirement to have gyroscope-based instruments only comes in with IFR (at the very least you need turn indicator due to lack of horizon reference).

It's not any weird local laws, it's common aviation laws :) though navigation is a big thing even in VFR ;)

The weird local law is that small planes are not allowed to fly IFR even if they are equipped for that and the pilot is rated. These planes are not even allowed to fly above a low-level cloud with partial coverage.

>I guess after people had to pay to meet the FAA's ADS-B mandate, this is another equipment update that will need to dealt with.

Have us Canucks even done ADS-B? The USA is way ahead of us on that one.

"Meanwhile, the ADS-B mandate in Canada has been under an indefinite suspension since November 2019. It was originally slated to begin in February 2021 but was placed on hold in response to stakeholder feedback."

https://www.ainonline.com/aviation-news/business-aviation/20...

Thanks, couldn't find anything. I knew that happened years ago and didn't hear much.

IIRC a major sticking point was "antenna diversity": in addition to having something point down, Nav Canada wanted antennas pointing up for space-based ADS-B (NavCanada was an initial investor in Aireon).

But the extra antenna is still a bit pricey, but given Canada's vastness, satellites were the only way to get good overage outside of major urban areas.

NavCanada/Aireon would also be using 1090ES and not the UAT that the US allows for lower-flying GA planes as well.

However, if you're near the US border, your transponder can (IIRC) broadcast that you have an UAT receiver on-board (even if you have an 1090 transmitter), and the FAA's gear may send out UAT data (e.g., weather, UAT planes).

* https://skiesmag.com/features/diversity-matters-canadas-perf...

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