As -Daniel- said, there was a track trait in the playtest. It allowed the weapon to ignore speed modifiers:
Track: Through the use of guided control surfaces or high- precision targeting, this weapon has been designed to attack fast-moving targets such as aircraft. It ignores all penalties for Fast Moving targets (see Traveller Core Rulebook, page XX).
no idea why it was removed though. To be honest, I didn't even realize it was gone until I saw this thread