Iside all that concrete is a steel mesh for stregth. Flying in the hanger is like flying beside a giant chain link fence and it's reflecting the signal back to the helo out of time/ phase with the original signal. This causes your glitch. Same reason you don't fly at a base ball field with the big parabolic fence designed to keep foul balls fromgoing into the stands, or in a tennis court with 20 foot high fences... It's pretty easy to figure out if you think about it.

I've flown my helo's in the hanger bay of an aircraft carrier while out on deployments with no issues... also flown airplanes and cars off the flight deck during down time.... no issues with interference and we had so huge high power transmitters on the carrier...