A helicopter is hovering over a crowd of people watching a police standoff in a parking garage across the street. Stewart notices the shadow of the helicopter is lagging approximately $50 \mathrm{m}$ behind a point directly below the helicopter. If he is $2 \mathrm{m}$ tall and casts a shadow of $1.6 \mathrm{m}$ at this time, what is the altitude of the helicopter?