PS-MOD-069 · r3
MODE TRANSITION
OBSERVED
ENGAGED · ONGOING
FALLBACK STATE UNDEFINED
What it does when nobody is reachable was never anybody's decision.
01 DEFINITION
Condition in which the behaviour a system takes up on becoming unreachable was settled as an implementation detail rather than chosen, so a state nobody decided becomes the governing one exactly when nobody can change it.
02 CONDITIONS
UNCERTAINTY
MISSING
What the thing will do while unreachable is not stated in any document the operator can reach.
TIME PRESSURE
MODERATE
Becoming unreachable is not itself urgent; what follows it may be.
ERROR ASYMMETRY
ASYMMETRIC
Stopping and carrying on both cause harm, and not the same harm to the same people.
OPERATOR STATE
SUPERVISORY
The person is answerable for behaviour they are not in a position to influence.
03 WHERE IT APPEARS
MEDICALWhat a device does when it stops receiving orders is a property of its firmware rather than a clinical decision.
INDUSTRIALEquipment behaviour on losing its supervisory link was inherited from a previous installation and never stated.
ENERGYA controller's conduct when isolated from its master was configured once and is not part of any operating document.
MOBILITYWhat a vehicle does when it can no longer reach its service is decided in code and met on the road.
MANUFACTURINGA cell's behaviour when the network drops is whatever the integrator chose and nobody has revisited.
AI EXP.What an automated process does when its upstream stops answering is an unstated default that becomes policy.
04 WHAT AEON WORKED THROUGH HERE
Becoming unreachable was ordinary rather than exceptional, and what the elements did while unreachable had never been written down anywhere — it was whatever the last build did. Stopping and continuing were both defensible and the choice had been made by nobody. The work went into naming that behaviour as a decision with a place to be seen, so that the people who would answer for it knew what it was beforehand.
What stays unresolved is how much an unreachable thing is entitled to do on its own — one that stops is a hazard where it stopped, and one that carries on is carrying on under the last instruction it happened to receive.