Any practical Biefeld–Brown device that was able to carry a person will require in excess of 50 kV to 200 kV with the anode pointed up. The apparatus is really a condenser with a power supply and an electric generator. This blog post will limit its scope to the most safety critical items the subsystem containing the high voltage electrostatic generator and the condenser assembly itself.
It is so critical to note that if the device has a person on board they will be very close to a high voltage negative condenser plate which may or may not be spinning (see Searle effect). Compounding the problem, Biefeld–Brown devices aren't exactly heavy lifters. It would be hard enough to fit the requisite generation equipment on-board with a pilot. How would such an apparatus lower its hazard of touch potential under cramped circumstances?
A strong dielectric material would help but, again, fitting everything is such a cramped space would yield a potential touch potential hazard rate well in excess of the transportation tolerable hazard rate of ten to the negative nine hazards per hour. MIL-STD-882E specifies the safety requirements and method for achieving a suitably low hazard rate for an aircraft or aircraft subsystem. The condenser may require Electronics Parts Reliability Data data to infer rates that would allow compatibility with 217Plus:2015.
So would a remote controlled drone work? This machine could be lighter as it does not need to carry a person or the associated fuel. A lighter aircraft could use a lower condenser voltage. This voltage would still need to be 30 kV to 80 kV and would be hazardous if the drone were to crash. This type of high voltage drone should not be used in areas with any population density.
References:
United Sates of America Department of Defense, System Safety: Standard Practice MIL-STD-882E, Ohio, U.S.A., 2012.
RiAC, Electronic Parts Reliability Data-2014, Up-state New York, U.S.A., 2014.
RiAC, 217Plus:2015, Up-state New York, U.S.A., 2015.