Is there a term to describe systems prone to tipping into failure

Factual Questions
1

I’m looking for term (more specific than just ‘sensitive’ or something), to describe systems that are capable of functioning well within a certain parameter band, but where deviation outside of those parameters causes a sudden or cascading failure without possibility of restarting.
For example, the looping waterslide mentioned in this thread - it’s possible for a certain-sized stream of water to flow down the incline and pick up enough speed to execute the loop and leave the system, however if the flow is reduced, a point will be reached where the water cannot loop around and rapidly starts to accumulate in the elbow of the loop, preventing the system resuming to normal function even if the flow is restored.

2

Metastable?

3

I was sure the first reply was going to be “Windows.”

4

I think perturbable systems might be more descriptive than metastable. The later implies a system that will become unstable with any impulse, like a marble balanced atop a basketball, where as I think the OP’s question pertains to systems which are stable as long as inputs are kept within certain parameters but rapidly become unstable and/or chaotic outside that range.

Stranger

5

Not sure if this is what you’re looking for, but Charles Perrow wrote Normal Accidents, a highly-regarded theory that says that many modern systems are both complex and tightly coupled and thus “normally” prone to failure…and it is our expectation of safety and success that may need to be adjusted. Perhaps an extremely fancy way of saying “Shit happens”?

There’s a quickie overview of it here:

NASA presentation on Normal Accidents

Sailboat

6

How about Brittle System?

7

You just described web and database servers to a T.
I reviewed a system that can handle 1300 transactions per second, just fine, only a quarter-second lag time for responses.
By the time you get to 1500 transactions, the reaction time is out to 2 seconds and you get occasional time-outs.
By 1600, the system is what most people would describe as hosed.

8

Catastrophic failure at boundary cases?

9

For simple English, how about “precarious”?

10

“Ellen Degeneres Show”?