Most small UAS use the 2.4 GHz and 5.8 GHz unlicensed radio frequency bands for the control link between the control station and the aircraft. AC 107-2A warns that operating in an area with many other wireless signals on these same bands, such as dense housing or office buildings, can lead to —
Why: AC 107-2A § B.6.1 explains that the 2.4 GHz and 5.8 GHz bands are also used by wireless computer networks, and interference on these bands in areas with many wireless signals is a reported cause of loss of control (LOC) and fly-aways.
Misstates licensing rules; AC 107-2A § B.6.2 specifically identifies 2.4 GHz and 5.8 GHz as unlicensed bands that may be used freely without FCC approval.
Invents a link between frequency interference and the groundspeed limit; the 87-knot limit in part 107 is unrelated to RF interference.