Pardon me if this sounds like a buzzkill, but is modifying plane equipment legal without re-certification? I remember reading a previous post on HN on why same electronics on airplanes are 10x more expensive due to rigorous FAA certifications.
Pilot here. Generally speaking, FAA regs allow owners to update GPS databases (14 CFR 43.3 [0]) if we're provided with the means to do so. However, this method of doing it may be legally questionable.
The crux of the matter is this regulation (14 CFR 43.3(k)):
> (2) The pilot must comply with the certificate holder's procedures or the manufacturer's instructions.
> (3) The holder of operating certificates must make available written procedures consistent with manufacturer's instructions to the pilot that describe how to
Basically, while as an engineer I can appreciate the technical cleverness of this, I would definitely talk to an aviation lawyer first before trying this myself.
Interestingly, by 14 CFR 43.3(k) even the "official" method described in the article is noncompliant, as the device is removed from the aircraft, and put into a docking-station at home, loaded via RS232.
I also understand the need to follow procedures, even if there are cases in which they are clearly nonsensical or obviously without influence on air safety -- just because it's not guaranteed that everything that seems to have no influence on safety actually does have no influence on safety.
But: I had seen photographs of an old floppy drive in a B737 (I think) which was used to load updates to the FMS. Then there's a version with USB. Both storage devices could be inserted into a PC, with junk stored on them, or swapped with a completely unrelated disk/usb-stick. Inadvertently, or even with malicious intent.
So the risk of arbitrary data on the floppy drive must have been mitigated (by signing the FMS updates, checksums, ...) and considered acceptable during the design of the system.
The same, I think, should hold true for the memory card in the article: If traditionally these cards had been shipped around by postal mail, I'll claim that the possibility of damage which isn't visually apparent must have been taken into account, and a procedure been put into place, such as a CRC check to be performed after the swap, or a self-test after every turn-on of the unit. Afterwards, the card should be considered "good", independent of the method by which the data was loaded.
Does that make sense, or am I overseeing something obviously here?
> Interestingly, by 14 CFR 43.3(k) even the "official" method described in the article is noncompliant, as the device is removed from the aircraft, and put into a docking-station at home, loaded via RS232.
It's not noncompliant, it just means that owner maintenance on this GPS isn't possible and has to be done by a specialist. A general rule I go by is if something needs to come out of the panel, it needs a mechanic or avionics tech to do. This unit is from 1996. IIRC we weren't allowed to do our own updates until 2012 or so. So it's not surprising that owner maintenance may not be legally possible on it.
I can pretty easily construct a scenario where doing something like this gets you in trouble. Chances are nothing will happen but it's all about your risk tolerance. Mine is pretty low.
He has added an interesting disclaimer "Please note: I am in no way saying that you can, should, or are allowed to fly with a card updated in this way (even though the bits in it are identical). I am not claiming that I plan to or am flying with such a card. All experimentation was performed on a card and a GPS that is not used for IFR flight."
Also author appears to have commented on this thread with a similar disclaimer. Very neat hack, but yea, walking a very fine line with the relevant aviation authority :(
Yes, I see the disclaimer. You are walking an incredibly fine line.
If you did this to the GPS that is currently in your airplane, unless you are also a licensed A&P or your aircraft is registered as experimental, you potentially made an illegal modification to your aircraft. You almost certainly voided the IFR rating on your GPS. You may have voided your airworthiness certificate. You may have also voided your insurance policy.
Now, there's a lot of qualifiers in there because ... I honestly don't know. There's lots of rule making about what maintenance owners can do when to comes to physical parts of the plane, but hardly any about software. That's why I would talk to a lawyer and A&P first if you do decide to fly with this. It might be fine, especially given the age of the GPS in question, to just have someone sign off on it. But likely only an attorney up-to-date with FAA rule making could tell you that. To me, this looks legally problematic at the very least, but IANAL.
Yes, it is your GPS, and your airplane, and you should be able to do what you like with them, but that's not how the FAA works. You and I both know that, as pilots, we have almost no legal protection. It literally just takes one FAA bureaucrat wanting to make a name for themselves to really make your life a living hell over this if they want to. Never underestimate the pettiness of government bureaucrats when it comes to following rules. If someone from the FAA sees this, they're likely going to want to ask you some questions.
I'm not going to tell you how to live your life. Only you can determine what your risk tolerance is, and the reality is that probably no one will find out, you will have no issues, and you'll be just fine. Again, it's an impressive and very clever feat of reverse-engineering, and I don't want to take anything away from that. From one engineer to another, really, it's well done. But if you have an incident flying IFR on this now-unrated equipment, and the FAA finds out about this, it will likely end very poorly for you.
All I can say is that, if it were me, I would not fly with anything in the airplane that would endanger me or get me in trouble with the FAA. I would not even want to take a chance with something like this in my airplane.
I would at the very least 1) talk to an aviation lawyer, and 2) get someone to sign off on what you've done. I would also provide the relevant documentation on your webpage about the legally questionable nature of this modification.
Or 3) slap an "INOP" placard on it and get on with the fun of flying.
Judging by the text and posts the author is well aware of all that, is this preaching really necessary here on HN? :/
The process of reverse engineering and hardware design itself is still very interesting to read about and I'm not sure what your post really adds besides negativity?
I found the reverse engineering part interesting too. Like I said, it's incredibly well done. But it's also legally problematic and anyone reading this should understand the risks they are taking. Fighting an FAA enforcement action will be far more expensive (think 5 figures) than just paying the money to do it the legally correct way. If someone does it wrong it might cost them their life (see paulmd's comments above).
Pilots operate in an complex regulatory environment and things that may seem okay from the outside are not okay to the government. It's so complex that otherwise well meaning and law abiding pilots each year run afoul of the various regulations, and there are few legal protections afforded to pilots facing an enforcement action. A good example of this is the relevant FARs about reimbursement for business expenses when flying yourself. They're not the same as driving and being caught breaking them could cost you your certificate.
Whole books are written about aviation law and attorneys specialize in it. And all pilots are expected to be familiar with them. But the devil is in the details, and that's where they'll get you,
He says he didn't put it in his plane, so he's fine. And it was a super interesting technical read. But others reading this need to understand the ramifications of doing this or something like it to an actual airplane is just asking for problems.
Sure, and that's what a disclaimer, like the one you even acknowledged, does. Make it obvious that this is something that he did for fun and that you shouldn't do the same unless you know the risks.
So, going back to izacus's comment, is the preaching really necessary? He gets it, and people who read this and are in a position to act upon the information (ie. have a plane, with this GPS, and want updates) also are likely to understand the ramifications, so, really, what does the preaching add, other than negativity, as was mentioned?
