Anyway regarding the ascension to heavens, it might not be
necessary that he is liberated even though he has ascended to the
heavens.
Even if a person reaches the level of the Anagami, non-returner
(3rd out of 4th stage of sainthood - Arhant is 4th stage), it is
likely that he will ascend to the 4th Brahma realm, and from there,
attain liberation.
It is also likely that many of those sages ascend to the heavens by
their practise and virtues.
By looking at http://www.accesstoinsight.org/ptf/dhamma/sagga/loka.html,
Five out of Seven abodes of the 4th Jhana Planes are only
accessible to Anagamis (non-returners) and Arhants.
But even when the Anagami rose to 4th Brahma plane, it still isn't
liberation yet.
Now let us look into Maha-parinibbana
Sutta
How the Blessed One Passed into Nibbana
9. And the Blessed One entered the first jhana. Rising from the
first jhana, he entered the second jhana. Rising from the second
jhana, he entered the third jhana. Rising from the third jhana, he
entered the fourth jhana. And rising out of the fourth jhana, he
entered the sphere of infinite space. Rising from the attainment of
the sphere of infinite space, he entered the sphere of infinite
consciousness. Rising from the attainment of the sphere of infinite
consciousness, he entered the sphere of nothingness. Rising from
the attainment of the sphere of nothingness, he entered the sphere
of neither-perception-nor-non-perception. And rising out of the
attainment of the sphere of neither-perception-nor-non-perception,
he attained to the cessation of perception and feeling.
10. And the Venerable Ananda spoke to the Venerable Anuruddha,
saying: "Venerable Anuruddha, the Blessed One has passed
away."
"No, friend Ananda, the Blessed One has not passed away. He has
entered the state of the cessation of perception and
feeling."59
11. Then the Blessed One, rising from the cessation of perception
and feeling, entered the sphere of
neither-perception-nor-non-perception. Rising from the attainment
of the sphere of neither-perception-nor-non-perception, he entered
the sphere of nothingness. Rising from the attainment of the sphere
of nothingness, he entered the sphere of infinite consciousness.
Rising from the attainment of the sphere of infinite consciousness,
he entered the sphere of infinite space. Rising from the attainment
of the sphere of infinite space, he entered the fourth jhana.
Rising from the fourth jhana, he entered the third jhana. Rising
from the third jhana, he entered the second jhana. Rising from the
second jhana, he entered the first jhana.
Rising from the first jhana, he entered the second jhana. Rising
from the second jhana, he entered the third jhana. Rising from the
third jhana, he entered the fourth jhana. And, rising from the
fourth jhana, the Blessed One immediately passed away.
--------------------------------------
His level of consciousness ascended to the level of the Brahmic
planes, but eventually he 'passed away' into Parinirvana. His body
was cremated by his fire of Samadhi, and his miraculous and
beautiful uncountable
shariras, were later distributed among kings (human), and even
the Nagas (dragons) and Devas (celestial beings).
However, Mahayana Buddhists know that his passing into
Mahaparinirvana is not ultimate (but more for show - symbolically),
he is still in charge of the 3000 world system and will still teach
within the 3000 world system.
