A

This letter is either /æ/ or /ə/ depending on its position in the word.
If it's the only stressed vowel in the word, it's /æ/

E.g.
cat, hat, fat, sat

In a few words it's pronounced /ə/
what -> ɯhat (wət)
mother -> maþor (ˈməðər)

Here are examples where "a" is both /æ/ or /ə/ in a word:
to animate (verb) -> ta animete /tə ˈænɪˌmeɪt/
animate (adjective) -> animat /ˈænɪmət/
animal (noun) /ˈænɪməl/
practical (adj) /ˈpræktɪkəl/
practicality (noun) -> practicalety /ˌpræktɪˈkæləɾi/