  In recent years, there is an increasing demand for unmanned aerial vehicles
(UAVs) to complete multiple applications. However, as unmanned equipments, UAVs
lead to some security risks to general civil aviations. In order to strengthen
the flight management of UAVs and guarantee the safety, UAVs can be equipped
with automatic dependent surveillance-broadcast (ADS-B) devices. In addition,
as an automatic system, ADS-B can periodically broadcast flight information to
the nearby aircrafts or the ground stations, and the technology is already used
in civil aviation systems. However, due to the limited frequency of ADS-B
technique, UAVs equipped with ADS-B devices result in the loss of packets to
both UAVs and civil aviation. Further, the operation of civil aviation are
seriously interfered. Hence, this paper firstly examines the packets loss of
civil planes at different distance, then analyzes the impact of UAVs equipped
with ADS-B on the packets updating of civil planes. The result indicates that
the 1090MHz band blocking is affected by the density of UAVs. Besides, the
frequency capacity is affected by the requirement of updating interval of civil
planes. The position updating probability within 3s is 92.3% if there are 200
planes within 50km and 20 UAVs within 5km. The position updating probability
within 3s is 86.9% if there are 200 planes within 50km and 40 UAVs within 5km.
