Drone altitude restrictions are AGL, not ASL.

I go out on top of the highest local mountain and send a drone up to 12,300' and the FAA won't care. I do the same thing over my house, they would very rightly be quite upset. (But I think it's BLM would care about the drone over the mountain--it's wilderness terrain, no powered vehicles of any type except for emergency use.)

But planes don't normally fly very low except when taking off and landing. Below 500' AGL and away from airports is normally not the realm of airplanes. Go above 500' AGL and you have a whole host of FAA compliance issues because now you are in plane space.

He's got it backwards.

"Language is a serial, low-bandwidth channel. It transmits one proposition at a time, sequentially. Each proposition can relate a small number of variables: “if X and Y, then Z.” Complex conditionals can extend this to perhaps five or six variables before the sentence becomes unparseable: “if X and Y but not Z, unless W and V, then Q.” ... "This is not a claim about human cognitive limitations. It is an information-theoretic claim about the channel capacity of natural language relative to the complexity of the models being transmitted."

No.

This definitely is about human cognitive limitations. Consider *why* that 6-variable rule is unparseable: Human working memory is typically about 7 items. His unparseable example has by a generous accounting 10 entities--6 variables and 4 relationships. (And by a strict accounting you need to count the "then", for 11 entities.) Very, very few humans could learn that. Knowledge must be chopped up into chunks small enough to fit into our working memory to be understood and incorporated into our models.

Once one chunk has been incorporated into our model we can then add another chunk to it, repeating until we have built up a complex model. And it's not just read, store, read another--each bit must be worked with to actually be modeled. (But this process does not need to be strictly linear--to take his stupid pedestrian, they can separately learn speed, distance, stopping distance etc and tie them together. But if his pedestrian cares if the driver is inattentive his model is wrong--why are you doing something that involves a moving driver being aware of you in the fist place??)

No. That famous demonstration only touched on the real failure mode--the rings were covering up other failure and in the cold could not do so.

The real test was creating a full-scale test of ignition, an engine containing mostly inert filler (to occupy the fuel volume) and just enough fuel to reach stable burning.

No. They were noted, the fact that they didn't destroy the vehicle was taken as evidence they wouldn't destroy the vehicle. Neither received any real scrutiny.

I do not even remotely trust his management anymore. It looks very much like corner cutting. Cut until it fails and back off a bit is not a good approach when you need some redundancy.

SpaceX was clear about their policy of flight testing earlier in the development phase. They expected to lose rockets, I do not believe those should count against the launcher.

They do not expect to lose a given vehicle. They are tolerant of losing some vehicles over time, because they understand that every flight may be affected by unknown unknowns. There is certainly no evidence that they expect to lose crewed vehicles, or that they are tolerant of crew loss.

I think the high loss rate for Starship can largely be traced back to the choice of using steel for the vehicle, which drastically reduces margins across the system. You could certainly say that they had a higher expectation of failure because they made that choice. In that sense, I understand your point. But to the best of their ability, they try to fly every vehicle successfully.

They haven't lost a crewed vehicle.

The only Starship loss that bothers me is the first one. I have no problem with "let's see if this works", I have a problem with dismissing the opinions of all the experts and launching without a flame trench. You don't need to be a rocket engineer to see that when you give all that energy no place to go a lot of it is going to get reflected back at the rocket.

What should be counted against them are the two operational Falcon 9s that were lost. The second one especially bothers me: we didn't really need that part anyway is not an answer to why the part failed!

> They haven't lost a crewed vehicle.

Yes, that's my point. SpaceX understands they need to do many unmanned flights before trusting a launch system with a crew. NASA is trusting Artemis with only a single unmanned flight. That is very high risk tolerance, to the point of recklessness in my opinion, compared to SpaceX.

Challenger: Saying don't go would probably have cost them their jobs.

Columbia: It had previously barely survived foam damage. They figured out where the offending foam had come from and fixed that part--but only that part.

I don't see it so much as no spacecraft is safe to fly, but rather no spacecraft should have a crew on it so long as there are major safety questions.

This is not the Shuttle that couldn't be flown without a crew.

The shuttle people never looked.

That there was blowby where there should be none was known, but nobody dug into why. There was no determination that it wasn't enough to be a problem, just an observation that it hadn't blown the booster up yet. For something with a wide spread in the data points, no way to model the maximum expected values.

Once they got serious about looking it didn't take much to reproduce the problem. They built a single joint, mostly filler inside, fuel to model the real thing during ignition. Maybe worked, maybe spot-welded, maybe complete failure. The colder the more likely to fail.