*Although self-contained, this question is a follow-up to [this earlier one](https://mathoverflow.net/questions/428926/fragility-of-large-cardinals-with-respect-to-transitive-end-extensions/428948#428948).* Work in $\mathsf{ZFC}$ + "There is a measurable cardinal," and let $\Omega$ be the least measurable. (Measurability is massive overkill here, I just want to make sure I have plenty of "room," so to speak.) Say that a sentence $\sigma$ is an **inaccessibility safety net** iff $V_\Omega$ satisfies each of the following statements: - $\mathsf{ZFC+\sigma}$ has arbitrarily large transitive models, and - whenever $M$ is a transitive model of $\mathsf{ZFC+\sigma}$ and $\alpha$ is $M$-inaccessible there is a transitive end extension $N\supseteq M$ such that $\alpha$ is $N$-inaccessible and $N\models$ "There is an inaccessible cardinal $>\alpha$." As far as I can tell, Farmer S's argument at the above-linked question - which relied on [pointwise-definable models](https://arxiv.org/abs/1105.4597) - does not prove that inaccessibility safety nets cannot exist (consider e.g. $\sigma\equiv\forall x[\mathsf{V\not=HOD}(x)]$). > **Question**: Is there an inaccessibility safety net? In some sense an inaccessibility safety net has to axiomatize (a superset of) the consequences which the existence of a "large" inaccessible would have for a "small" inaccessible. Of course this is rather vague, but hopefully it helps motivate this question.