I am not a FN but the ones at the facility I work for are female. I think there are 3 of them...all female. When they go on a call it is one of them, a paramedic (all are male at our place) and the pilot (also all male). It varies I'm sure...just know I will not be a FN anytime soon and I have the deepest respect for those who are or want to be!
Our base is almost totally female for the nurses - and the medic I fly with is female. We're called "the featherweight crew" because we can basically transport any patient that doesn't max out our stretcher on weight.
i think it depends on where you are. I have worked for 2 programs in which mostly the nurses were females and paramedics male. i have seem programs though with not one female on the entire staff. Not sure about that one.
just remember as females we have been doing it backwards and in high heels for years to get the same recognition as males. if you are truley interested in becoming a flight nurse, prepare yourself well and you can't be turned down.