Vowel length is not phonemic in English.

Screwdriver   Sunday, December 19, 2004, 15:08 GMT
Mxsmanic was right. Check out dictionary.com,

''pho·net·ic ( P ) Pronunciation Key (f-ntk)''
''adj.
''Of or relating to phonetics.
Representing the sounds of speech with a set of distinct symbols, each designating a single sound: phonetic spelling.
Of, relating to, or being features of pronunciation that are not phonemically distinctive in a language, as aspiration of consonants or vowel length in English.''

http://dictionary.reference.com/search?q=phonetic