I am by no means an aviation expert, but my career was largely built on things like putting GPS and modern radios into military aircraft, writing flight planners, and so on.

I ask you to envision the logistics of a simple change. You want to implement X, and gee-whiz do I have some cool, new technology that makes it easy!!

Okay. Let's start. If we make mistakes people die, and careers end. I'll let you draw your own conclusions about motivations re that, but all I'll say is as an engineer I only ever focused on the former. So, huge testing and verification effort to show that my gee-whiz technology that works in some consumer device has acceptably low failure modes, does not negatively affect pilot work flow, can work under the conditions of flight (-55C to 70C anyone?), over the wide performance characteristics (high G, high vibration, salt water, high radiation), and so on.

Okay, you did all that! Let's start bolting it on the planes!

No.

Let's write and get approved training programs for all the maintenance workers. Then, let's train them - across the whole world. Let's write and get approved training programs for the pilot. We will fit it into their refresher training, have new mandated training, or what? Basically, rewrite all the training curriculum that is out there. Get it into the schools, so the pilots coming fresh out of school aren't behind. Again, across the world.

Oh, this interfaces with the towers? Okay, so do all that again with the towers. Hmm, you want this 2013 technology to seamlessly integrate with some core memory technology - that should be easy. Perform a study, put out RFQs, get bids, select the best bidder, have them build the system, manage them through the cost overrun, opps, 3 months before deployment Congress mandates that that core-memory system be retired, and oh, how will this work in the 168 other countries?

Got that sorted. No, wait, no one in the tower knows how to use it, no one knows how to install it, no one knows how to maintain it. Let's throw money and time at that! Oh, unions. I hate unions. ATCs have a union. This could take awhile....

Finally, it is 2020, and I am rolling out, um, 7 year old technology that is entirely obsolete and no longer supported by the manufacturers. Oh, they'll support it if you throw enough money at it - get your $5 microprocessor at $1000 a pop.

Meanwhile, the entire world is filled with aircraft still using the old system. So, we mandate a phase-out by 2035. Just another 15 years of supporting the old and new systems in parallel. I'm sure that'll be pretty cheap.

People who work in the field will rightly accuse me of hand waving, and especially of over-exaggerating some difficulties (not every modernization project hits every possible snag that exists). But this is still a useful sketch the scope of the problem. I've spent time talking to very high people in the FAA. They are not unaware of the old systems and their limitations, nor are they bumbling bureaucrats (pet peeve - it is easy to villanize faceless people, and that is very lazy thinking). We in industry are forever proposing new ideas, better technology, and so on (let's face it, they are all trying to feed at the trough of government spending, and getting your system mandated is a company maker). But the price tag for my handy,dandy system is at the noise level compared to the cost of the logistics of deployment.

I am not arguing that there is nothing to be done, or that everyone is working maximally efficiently right now. Certainly the US is behind other countries in some areas of aviation technology. But it is not in any way a trivial problem, one of "just bolt a new radio to the plane and trash the old ecosystem".

edit: consider, for example, the Rockwell Collins DTU-7000 Data Transfer Module (https://www.rockwellcollins.com/sitecore/content/Data/Produc...). This is absolutely modern hardware in the aviation world. It is PCMCIA. And how exciting it was to get. You would not believe the cost and size of the old system - we would jealously keep tracking logs of, I forget, a few MB of flash memory units that cost thousands and thousands (and thousands) of dollars. There is some even more modern stuff being rolled out that uses usb. But consider, when this is something that contains your flight plan, your maps, and so on, the cost of a stray gamma ray blowing away a byte. Mull on how much testing this hardware goes through. And then factor in all of the logistics above. We already don't have money to own the old system, and now I have to go to all this further expense, to save what is truly chump change (that thousands and thousands and thousands number) in the end? Millions to save thousands.

Of course, we have to modernize, we can't store rich maps on tiny memory, so we spend, and spend, and spend. And then get a front page HN story about how old everything is! Well, there's a reason for that.