There are a minimum number of hours specified by Federal Aviation Regulations (FARs) Part 61. I don't know the average now, but the national average used to be about 20 hours over the minimum. Those students who took less than the national average were those who took 3 to 5 lessons a week (some went 7 days).
A rare but very serious risk associated with blood transfusions is transfusion-related acute lung injury (TRALI). It occurs more often with platelets and plasma than with red cells. TRALI is a poorly understood condition, in which a personâs lungs suddenly become very inflamed within six hours of the transfusion.
In severe cases of anemia, or with ongoing blood loss, a blood transfusion may be necessary. Blood transfusions for anemia. Doctors attempt to avoid blood transfusion in general, since multiple lines of evidence point to increased adverse patient clinical outcomes with more intensive transfusion strategies.