Would anyone know what sidearm an Army pilot (P-51 in the Po Valley)would have carried in WWII?  Also would anyone know what, if any, sidearm would a crewman in a B-24 in the late Pacific campaign worn?

I was named after two uncles who died 3 months apart in WWII and I'm working on their history as part of the family history.

1911A1s.

my  dad was a bombardier on B-17s AND B-29s. He told me that bombardiers were supposed to carry a .45 to destroy the bombsight with if the ship went down.

same would hold true for B-24 guys.

fighter pilots carried .45s, too.

Ok, I could be wrong but I remeber my Grandfather saying that he had a .38-Special. He flew a Corsair and was in the Pacific carrier wars.

My grandfather was a B-24 pilot in Italy, and he carried a 1911.  Seeing as how many of the pilots from Italy went on to the Pacific after VE day, I would think that they would have carried the same thing.
As far as a "crewman", I'm not sure if everyone was issued a sidearm in a B-24 or only the officers.  According to Ambrose's "Wild Blue", everyone on board a B-24 was a sergeant or better, but my grandfather's brief memoirs claimed that most of his enlisted crew were privates of some variation.  I wish he was still here for me to ask him for you.
My step-grandfather (sadly also passed on) was a fighter pilot, but I know very little about him or his career.  I do know that he was quite a celebrity around Eglin AFB, and was one of the fighter pilots to make the switch from props to jets.  He was also a member of the predecessor to the Blue Angels.  For the life of me I cannot remember the name of this group.

my maternal grandfather was a b-24 navigator, and he verified this also.

The general consensus seems to be either the M1911 or a S&W .38 Revolver.

Thanks to all for the info.  My Uncle Gordon was a radioman/gunner and a Corporal.  Uncle Jack was a Flight Officer.  Nearly sure they both died on their first mission.

My Father-in-Law is a genuine Ace from War2 flying Corsairs for the Marines in VMF211.  He carried a 1911A1.  He still has the 1911A1 that belonged to his best friend who was lost fighting Zero's over the South Pacific.  I take pride in keeping that .45 in good shape.

My dad was a command pilot of a C-47 on D Day and in Operation Market Garden and he carried a .45 Auto.

Could be a number of different handguns. M1911A1, M1917 revolver in .45 ACP, S&W "Victory" model in 38 S&W or 38 S&W Spl.. or any type of private purchase pistol. Believe it or not, there was a shortage of handguns in all services in WWII due to theft, black market and non combat types hoarding them. Any handgun especially the M1911A1 was a coveted weapon.