(CBS) — People pointing lasers at airplanes – it happens time after time in Chicago, and it’s more than a harmless prank.

Now, with travel season in high gear, the FBI is offering to pay big money to help catch people pointing the lasers.

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This epidemic of laser endangerment in Chicago and elsewhere has not caused any air tragedies so far. But experts fear it’s only a matter of time.

“When that pop goes off it dazzles you, and doing that at the precise wrong time could have a bad result,” aviation expert John Hoff says.

Hoff, a former U.S. Air Force officer, pilot and now an aviation attorney, says takeoffs and landings are historically the most dangerous times in flight.

Across the country, since 2005, there have been 3,592 laser incidents. In Chicago in 2012, there were 84; in 2013 there were 91; and so far this year, there have been 72.

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Laser pointers cheap and accessible. They sell well at one Northwest Side store.

“We’re very careful to who we sell them to, making sure they’re adults. We let them know they’re dangerous, but what people use anything for — we have no control over,” manager Paul Chapman says.

The feds are cracking down on these incidents, offering rewards of $10,000 to anyone who helps catch laser perpetrators.

In addition to those rewards, Uncle Sam is adding to the crackdown.

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These “laser dazzlers” are now subject to five-year prison terms.