Take a look at the sentence again:
Whenever Mike _________ his Cessna 152, a small airplane, he worried about
running out of fuel, hitting birds, and being abducted by alien spaceships.
The sentence requires the past tense of fly, an irregular verb. Flew is the simple past form.
| Verb | Simple Present | Simple Past | Past Participle |
| fly | fly(ies) | flew | flown |
Flown, the form you chose, is a past participle; to use it, you would need an auxiliary verb. Before you continue, review the rules for irregular verbs.
Go back to the sentence to try again.