I was puzzled when a native speaker of American English (grown up in Texas) recently told me that they would pronounce fairy and ferry the same. I would expect a "long" vowel in fairy and a "short" vowel in ferry, partly because of the double consonant in the latter.
This concept of vowel length, which is important in my mother tongue German, is foreign to that speaker and confuses them. Merriam-Webster provides two possible pronunciations for ferry, one of which is identical to the one for fairy, but their phonetic spelling doesn't seem to distinguish vowel lengths at all.
Obviously, given the heterogeneous English speaking community, there may not be one right answer at all; I'm interested in all accents and aspects.