Dear Lois.....may I suggest that you try www.google.com and type in the following:
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nichols field Philippines Islands
you should be able to get some information about the different outfits that were there at that time. It is possible that your brother was in the 5th Air Force at that time.
good luck with your research and if I can help you feel free to contact me via email if you want.
as a point of interest, I spent more than two years in the Islands after the war.