The FBI cited the Internet as a source for cheap , easy to purchase hand-held gadgets about the size of fountain pens which have become more powerful in recent years . Number of incidents is projected to reach 3,700 by the end of the year , FBI says . Comment: Lasers directed at aircraft can cause temporary blindness to pilots .
Number of incidents is projected to reach 3,700 by the end of the year , FBI says . Comment: Lasers directed at aircraft can cause temporary blindness to pilots .