>>1926575 (lb)

Just in case you really don't know, and are not one of them FE tards:

For small regions on Earth (like say 2km x 2km for example), some calculations can be much easier (and w/o too large of an error) performed as if Earth was flat. Makes things a whole lot easier …. and that doesn't mean those people doing it are not aware of this approximation (much less that they think Earth really is flat). 'nough said.