Learn Italian: Non ho ancora perso un volo. - I have not yet missed a flight.

When using the two-part past tense (passato prossimo), short adverbs of time like ancora (yet) usually go right between the helping verb (ho) and the main verb (perso). Notice how it is different from English, where 'yet' often goes at the very end of the sentence.

Does ancora mean 'yet' or 'still'?

It can mean both! When paired with non in a negative sentence, the phrase non ... ancora means 'not yet'. If the sentence were positive, ancora would mean 'still' or 'again'.

Doesn't perdere (and its past form perso) mean 'to lose'? Why does the translation say 'missed'?

Exactly! In Italian, you do not 'miss' a train, bus, or flight; you 'lose' it. So, ho perso un volo literally means 'I have lost a flight', which translates naturally to 'I missed a flight' in English.

Is perso a regular verb?

No, perso is an irregular past form (past participle) of the verb perdere (to lose). If it were a regular '-ere' verb, it would end in '-uto' (like creduto), but instead it becomes perso.