Her asthma has 'flared up' again. [=her asthma has become suddenly active or worse again]
When the crew saw 'flares', they knew the other ship was in trouble.
The fire is smoldering and there is still a danger of 'flare-ups'.
(..) I'll start the fire. Fascinating. We'll see if breeze try to blow us tonight. Now won't we? Hey, I think I saw its flare. Any chance I can squeeze in there with you? Isn't there someone else you can annoy? Friends? Family? Poison reptiles? My family is bad. They just kind of migrate without me. (..)2002 Ice Age