View Full Document. Ice Pellets Ice pellets (also called sleet) are refrozen snowflakes. They occur when a layer of air aloft is warm enough (> 0 ï° C) to melt snowflakes into raindrops but the air near the ground is cold enough to freeze the drops.
acarid - very small free-living arachnid that is parasitic on animals or plants; related to ticks. 1  mite - any of numerous very small to minute arachnids often infesting animals or plants or stored foods. 2  Acaridae, family Acaridae - mites.
An airborne collision avoidance system (ACAS) is a type of Ground Collision Avoidance Technology (GCAT) that operates independently of ground-based equipment and air traffic control in warning pilots of the presence of other aircraft that may present a threat of collision. Obstacle Collision Avoidance System is a ground based system that uses a low powered radar mounted on or near the obstacle. 2  The radar detects aircraft in the proximity of the obstacle and firstly warns aircraft via flashing medium intensity lights and secondly warns aircraft of the obstacle via a VHF broadcast.