In areas of large populations such as coastal areas or the northeast the majority of programs are rotorwing. Areas like the southwest, Alaska and the Rockies have a combination of rotor and fixed wing programs. The type of program depends on the distance their patients are from definitive care. Typically if patients need transport to a tertiary care facility greater than 100 miles, a fixed wing aircraft may be used. There are some physical requirements to become a flight nurse.
Some programs do limit the weight of crew members.
The issue is not discriminatory against those overweight or being tall. It is merely a law of physics. You are always part of a team. An important and desirable aspect of flight nursing is being able to be autonomous. Many programs have established guidelines, policies and procedures that the flight team can institute without ever speaking directly to a physician.