Possessive pronouns

[Gogo_james]

My Korean brother-in-law was going to be flying back to Gimpo yesterday from Busan the same time I was flying in to visit my sister. We were supposed to be on the same flight, but he was running late. He missed his flight and couldn’t get ahold of my sister so he texted me this: “비행편 다시 예약해” Long story short, I couldn’t tell if he was asking me to rebook MY flight, help him rebook HIS flight, or if he was just telling me he was going to reschedule his flight himself. Without a possessive pronoun, how can I tell whose flight is being rescheduled and by whom? Should it just be understood based on the context? His English isn’t good enough to explain it to me and my Korean is not good enough to understand (yet). Thanks a lot!