If I wrote a navigation app for pilots, designed it to run on non-built-in tablets, and included a disclaimer and warning not to rely on it (I would hire a lawyer for this part), would that be legal, and would my software have to be certified by some process?

  • 9
    $\begingroup$ Note that in general, you cannot lawyer away rules and regulations. If you write an app to do X and try to disclaim its use for purpose X, you have another problem, namely that your product isn't fit for purpose. You could hire a lawyer to give you an informed opinion whether your product would be compatible with FAA regulations, but expect to pay for that. $\endgroup$
    – MSalters
    Jan 12, 2023 at 14:18
  • 1
    $\begingroup$ @MSalters can't you also disclaim the warranty of fitness for purpose, as many open source licenses do? Of course, add too many disclaimers and people likely won't buy your software, but I don't think there's a legal issue. (I will definitely hire a lawyer before I make any decisions regarding this issue.) $\endgroup$
    – Someone
    Jan 12, 2023 at 18:55
  • 2
    $\begingroup$ IANAL and I don't have the slightest clue how this works in the US, but at least in several EU countries you can't sell a screwdriver with a disclaimer saying it is not to be used for driving screws, but you could give it away for free. I suspect that might be what makes it work for free software. $\endgroup$
    – TooTea
    Jan 12, 2023 at 20:30
  • $\begingroup$ @Someone: Open Source is different; the license grants an exception to copyright. Typically use of the software isn't even covered by the license (e.g. GPL), only copying the software. Hence such a license needs to make clear what it does cover (copyright), and what it doesn't cover (warranty). $\endgroup$
    – MSalters
    Jan 13, 2023 at 12:09

2 Answers 2


Tablets and other portable devices are not part of the aircraft's type certificate, so they are not required to be certified. Therefore, neither is the software.

For equipment permanently installed in aircraft the rules are different.

  • 5
    $\begingroup$ As I understand it, airlines now provide various operational manuals - checklists, etc. - on tablets for use before and during flights in order to save on the cost and weight of paper. Do those need technical certification? Or do they just have to sign off that "this is an exact duplicate of the paper version"? $\endgroup$ Jan 12, 2023 at 17:31
  • 4
    $\begingroup$ @manassehkatz-Moving2Codidact: On a related note, are there requirements regarding the quality of paper used for paper manuals? Manuals printed on thinner paper might weigh only half as much as the same number of pages printed on thicker paper, but be more likely to be accidentally rendered illegible. $\endgroup$
    – supercat
    Jan 12, 2023 at 18:49
  • $\begingroup$ @manassehkatz-Moving2Codidact, good question, I may add something about EFBs here later... Supercat, I think that's an unrelated question. Ask separately if you like, but I wouldn't know how to answer it. $\endgroup$ Jan 12, 2023 at 23:54
  • $\begingroup$ @MichaelHall: If there are specifications regarding the durability of manuals, that would seem like an explicit acknowledgment that they are to be treated as safetly-critical flight equipment. $\endgroup$
    – supercat
    Jan 13, 2023 at 16:29
  • 1
    $\begingroup$ @supercat, I'm not completely disagreeing with the premise of your question and comment, but in all my decades I have never heard of paper publications referred to as "flight equipment". Nor have I come across any specification for durability. They are replaced at regular intervals as new versions come out, and if you tear a chart or drip sweat on your approach plate you simple grab a new one whenever you prepare for your next flight. It's a consumable paper product - that's a far cry from certified hardware. $\endgroup$ Jan 13, 2023 at 17:09

Like any other "physical" component of an aircraft, also software must show compliance to airworthiness regulations in order for it to get approved by certification authorities like FAA and EASA.

The defacto standard used worldwide to show that software complies with these regulations is called DO-178C. In particular, FAA and EASA define it an "acceptable means, but not the only means, for showing compliance with the applicable airworthiness regulations for the software aspects of airborne systems and equipment certification".

DO-178C is basically the framework within which both industry and certification authorities moves to develop and demonstrate (the former) and approve (the latter) avionics' safety.

Also other safety-critical industries like railroad, medicine, nuclear power and so on use very similar standards of certification.

DO-178C defines five so-called "Development Assurance Levels" i.e. five levels of software criticality according to how much dangerous the piece of software under scrutiny is. In particular, the criticality can be (from Wikipedia):

  • Catastrophic - Failure may cause deaths, usually with loss of the airplane.
  • Hazardous - Failure has a large negative impact on safety or performance, or reduces the ability of the crew to operate the aircraft due to physical distress or a higher workload, or causes serious or fatal injuries among the passengers.
  • Major - Failure significantly reduces the safety margin or significantly increases crew workload. May result in passenger discomfort (or even minor injuries).
  • Minor - Failure slightly reduces the safety margin or slightly increases crew workload. Examples might include causing passenger inconvenience or a routine flight plan change.
  • No Effect - Failure has no impact on safety, aircraft operation, or crew workload.

Now, how thorough the development and the approval path of the software is, directly depends on which criticality level the software posses. In particular, software belonging to the fifth and last category i.e. software which poses "no effect" on the airplane's safety, does not need to show any compliance with airworthiness regulations.

Are there certification requirements for software that is intended to be used in flight, but runs on uncertified hardware and is not safety-critical?

So, anything running on a personal tablet/pc/smartphone must not be certified for the simple reason that it is not a threat for the flight's safety: you may well forget it at home and fully be able to safely fly anyway.

Anyway, if the piece of software running on the tablet becomes safety critical, i.e. if it belongs to one of the first four levels previously defined, then not only the app but also the operating system as well as the hardware would have all to be certified.

  • $\begingroup$ An example of something with no effect would be a video camera used to film the flight. Any navigation app would be at least minor (increased workload), right? $\endgroup$ Jan 13, 2023 at 8:12
  • 2
    $\begingroup$ It increases workload if it breaks. $\endgroup$ Jan 13, 2023 at 8:24
  • 2
    $\begingroup$ Can you imagine a navigation app which is not needed to fly and does not increase workload if it fails? $\endgroup$ Jan 13, 2023 at 8:36
  • $\begingroup$ uh, the usual definition? a computer program that one might run on a tablet in order to navigate? $\endgroup$ Jan 13, 2023 at 11:33
  • 1
    $\begingroup$ @user253751: "Not for primary navigation (I hope)" then we hope the same 😅 I suppose that if an accident happens and it can be demonstrated that the pilot was distracted by such apps then it won't be funny for the pilot... Everything that does not belong to avionics should be left either on ground or to the passengers. Piloting (even biking) needs concentration. $\endgroup$
    – sophit
    Jan 13, 2023 at 15:27

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .