(the video above explains it)

but to put it simple the pilot can see outside the otf stomach allowing them to fly without crashing and can control parts of the jet when in jet mode/foxtrot but the otf/dragon can also control this as well

for example, when masotan got scared, he made it that hisone wouldn't be able to see as he got scared by the group of people

this only works if the pilot is wearing the helmet because if not, they can't see anyway that's why they need the helmet to see in the first place.