No they haven’t. Flying is the easy part. The hard parts are navigating and communicating. Even then, even the largest airports will only support precision approaches on some runways in some directions because maintaining ILS equipment is expensive. What happens when you push the button and there’s a massive crosswind across the ILS runway? Also communication standards have ossified such that the only way you can talk to ATC is through 50s era radios. That means any fully autonomous aircraft would have to be able to accept verbal commands and produce verbal acknowledgments. The technology is so bad that a simple stuck mic can shutdown an airport. https://youtu.be/Wcq6KipBOro

I was thinking more "broadcast we are under attack, or pilot unconscious" as the communication, and land (subject to external control?)

They've had autoland for a while. Maybe in this context it means the nearest ILS runway, or nearest externally directed ILS runway. (just not landing in the side of a skyscraper)

Yes and auto land capability is not always available. Even today object avoidance is a hard issue. What happens when the aircraft flies into a flock of birds or some other obstacle, like another aircraft on the way to the runway. What happens when two planes both push the button at the same time and decide to both use the same runway? Autopilot even in aviation is a misnomer.

What happens if they fly into a building because they don't have the button? It's a management of risks.

Besides, there can be a back-link and information updates for the landing box to manage situations with two or more planes in emergency mode.

Having a unpredictable button which may significantly increase risk to an aircraft and others is not risk management no matter how dire or remote it’s predicted usage would be. First thing any knowledgeable malicious actor would do is pull the breakers associated with the system or simply disable it. This button would have a way to disable it assuming accidental or malicious activation right?

You will have a hard time creating a situation where pushing the button for an emergency landing creates a disaster.

It's very easy to imagine: the plane lands on top of another plane at a busy airport.

That happens if everything goes wrong but you cannot create that situation intentionally. Usually, pushing the emergency button would send an emergency signal, and air traffic control would clear the airport. Landing on top of another plane is an emergency within the emergency - very, very unlikely.

You can't just "clear" a big airport. There's also no way to guarantee that the emergency signal would be received.

You also can't guarantee that you won't be hit by a meteorite and yet you leave your house.

If you worry about the signal not being received and the inability of air traffic control to spot the irregularity, then only initiate safety landing when the plane receives an answer-signal. Otherwise, let the plane fly however it wants and let it crash somewhere randomly because most places are better equipped to handle a random plane landing than a regular airport.

I think you're forgetting that the button itself would only be useful in extremely unlikely contingencies. But sure, you can spin a story about a bunch of interconnected automated systems always working correctly in highly unusual circumstances. Doesn't usually pan out that way in practice.

Autoland isn't possible on just any ILS. Autoland doesn't exit the runway either.

Correct, but at least there is "brake to vacate" the runway.

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

When a pilot declares an emergency s/he can rely on the airport and airspace around it being cleared by flight control. If a hypothetical red button was pushed, there would be a standard procedure the aircraft computers execute which in turn can be relied on by flight control.

You can buy these for smaller airplanes: https://www.garmin.com/en-US/autonomi/

Basically a "pilot is incapacitated" button, it will pick the nearest airport and attempt to land there, and will even communicate with ATC. I believe the idea is that if you're a general aviation pilot flying with your family and you keel over, they can press this button to get down safely.

Garmin ships a feature called autoland. I think at least one plane is shippng with that.

Austin Meyer (of x-plane fame) actually build an ipad app that can be hooked up to the autopilot (he actually did this at some point but never shipped the integrated product probably for certification reasons) to do exactly this. It's called xavion: http://xavion.com/. Basically the app calculates the safest glidepath to the best airport for you and guides you to that. The feature is designed for engine out scenarios where pilots don't have a lot of time for making good decisions. It basically continously updates its plan as you are flying based on glide ratio, altitude, runway length and a few other factors.

The autopilot integration is probably not all that hard to do. It's just tricky from a legal point of view.

The problem is security. How do you prevent that such a system is unhackable and can't be misused remotely? That's the number one concern in all of these industries these days.

The same way you protect all other flight-essential electronics? You air-gap it.

This, this is why we can't have nice things. I understand the hacking concerns, but really, it seems that we've constructed arbitrary and next-to-impossible problem-space boundaries that appear to only stifle change and solutions to big problems.