The correct spelling of the phrase "wast mid air" is "waste mid-air." The IPA phonetic transcription for "waste" is /weɪst/, with the "ai" pronounced as a long "a." "Mid" is transcribed as /mɪd/, with a short "i" sound, and "air" is transcribed as /ɛr/, with a non-rhotic vowel sound. The phrase, therefore, means "waste in the middle of the air," and is typically used in aviation to describe airplane fuel or debris discharged from aircraft.