“I’ll call you when I get there.”
This could be said to a person who comes to see me off in a terminal, I think. But this ‘will’ seems to be somewhat awkward, in that ‘will’ denotes strong willingness that has an implicature of actualization (CGEL, p.212). We can see that this farewell saying is just stereotyped one and not rarely they forget about the ‘willingness’. So there seems to be a contradiction to use ‘will’ in the situation.
However, “I’ll going to call you when I get there” seems to be stranger than ‘will’. For although ‘be going’ is an intention not volition, it has an implicature of arrangement. It would be funny to arrange to call the person who comes to see me off.
Can the ‘will’ be okay in the situation?