Hello again Jasudho.
Yeah, that is yet another misunderstanding, this “consciousness that does not land”. It means “consciousness is not established” instead. (The term is appatiṭṭhita, not avirūḷha.)
It’s opposite, “consciousness is established” is another way of explaining dependent arising, in other words, the continuation of consciousness in a next life, when it is “established” in a new existence. “Consciousness is not established” is another way of explaining the cessation of consciousness. It is not a type of consciousness, but the situation when consciousness “is not established” to be reborn, in other words, when it will cease because there is no desire. I mean, take a proper translation and it’s clear:
If there is no desire, relishing, and craving for consciousness as fuel, consciousness doesn’t become established there and doesn’t grow. SN12.64, Sujato
Also compare SN12.64 (and even more so SN12.38-40) to the sequence of Dependent Arising of SN12.1, and it becomes even more clear that this is what’s it’s about. See here for a more detailed explanation of this, where I show that there is also a metaphor involved which is usually missed. (And, while you’re at it, here for yet another misunderstanding involving a supposed “nibbana” consciousness).
You’re talking about Ven. Thanissaro’s translations, I suppose. I highly recommend you switch to Ven. Bodhi or Ven. Sujato’s translations instead. They’re just better, especially when it comes to these kind of things. It’s unfortunate that Ven. Bodhi’s are not available for free, but they will be one of the best ways you’ve ever spend your money.
And, just checked, but even Thanissaro translated “then consciousness does not land”. This is clearly again a situation, not a type of consciousness. It doesn’t mean “consciousness that does not land*” but “consciousness when it does not land” (or become established). It describes the cessation of consciousness. Kind of ironic that this is then used as a support for the wrong idea of permanent consciousness…
Hope this helps. I know it used to confuse me until I was able to read the Pali, so that’s why I’m especially happy to help.