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 use the winch! Around the tree thing. Take this. Let's get the engine plates. You drive the rig! Hold the flare! / I am holding the flare!! Closer! / It's right in front of your eyes!! Hut! HUTTT!!!! Blood Bag! (..)2015 Mad Max: Fury Road