PatR
Premium Pilot
400 feet AGL is the max height allowed by the FAA
That is 100% NOT TRUE! Become proactive and read the actual law as published by the FAA. The only people that have a published height limitation are commercial operators working under Part 333 and 107. The amateurs and hobbyists are simply required to maintain safe separation from manned aircraft and to operate safely. Everyone is subject to the "careless and reckless operation of an aircraft" provisions in aviation law but a mandated 400' altitude limit, be it listed as MSL or AGL, is not part of the program.
Because someone said it on the internet does not make it true. Perform your due diligence to become accurately informed. I could post links to the law but you would not learn how to do things yourself if I did. I'll provide a hint and suggest starting with Part 336 and expanding from there. When you registered your model with the FAA you agreed at least twice in the registration process to remain below 400' but that is not part of published law.