When a police helicopter was flying overhead searching for a criminal suspect in Virginia Beach, Christopher Willingham did something he now acknowledges was “stupid”: He pointed a green laser at the helicopter – temporarily blinding the pilot and halting the search.

That stunt was not only stupid – it was illegal: Willingham was charged with a felony under a federal law that prohibits pointing a laser at an aircraft. In January, Willingham pleaded guilty to interfering with the authorized operation of an aircraft and is scheduled for sentencing this week.

Willingham was prosecuted under federal law because there was no applicable state law. That will change on July 1, when a new Virginia law kicks in.

The Virginia General Assembly passed the legislation – House Bill 87 – during its 2012 regular session. Gov. Bob McDonnell signed it into law on March 30.

The bill, proposed by Delegate Barry Knight, R-Virginia Beach, states, “Any person who knowingly and intentionally projects a point of light from a laser, laser gun sight, or any other device that simulates a laser at an aircraft is guilty of a Class 1 misdemeanor.” A Class 1 misdemeanor is punishable by up to 12 months in jail and a $2,500 fine.

The bill will be added to an existing state law that forbids interfering with the operation of an aircraft. Under that law, if the interference endangers the life of the pilot or anybody else, it’s a Class 6 felony, punishable by up to five years in prison.

Willingham, 28, was convicted for flashing a laser pointer at a Virginia Beach police helicopter from his backyard near Naval Air Station Oceana around midnight on Nov. 1. The helicopter was assisting ground units in pursuing someone who had run from a traffic stop.

The pilot suffered temporary blindness from the laser strike, and so the co-pilot assumed control of the helicopter.

The pilots flew over Willingham’s residence. He ran back into the house, came back out and then continued to point the laser at the helicopter, according to Neil MacBride, the U.S. attorney for the Eastern District of Virginia. When police arrived, Willingham confessed to flashing the laser pointer at the aircraft.

He pleaded guilty in January. Afterward, at a news conference at Oceana, Willingham apologized and warned the public against pointing lasers at aircraft. “It’s very dangerous,” he said. “A lot of people don’t understand how dangerous it is.”

Willingham’s case is not an isolated incident.

According to the Federal Aviation Administration, there were about 3,600 laser strikes nationwide last year, including 98 in Virginia. Willingham was the first person to be convicted of a felony in a laser-pointing case in the Eastern District of Virginia.

Naval Air Station Oceana reported 13 laser incidents last year. Oceana expressed its concern about the strikes to Virginia Beach officials, who then asked Knight to propose the legislation to protect naval and police pilots.

Another impetus for the legislation was a loophole in an existing law found by the cities of Virginia Beach and Chesapeake. The law stated that shining a bright light at aircraft was illegal but did not specifically cover laser pointers.

Knight said he was also influenced by personal experience. He is a licensed helicopter pilot who has been in a similar situation.

“I have had a bright light shined into my eyes probably on accident. It was very dark; a boater shot it, and it temporarily blinded me,” Knight said. “Your eyes can’t refocus for 20 seconds or so, and that can be disastrous when you’re flying along at low levels and fast.”

Even though a laser’s beam is small in diameter close-up, it widens by several inches over greater distances. Also, imperfections in the glass of a plane’s windshield cause the beam to expand even more within the cockpit. The stronger the laser, the more amplified the effect.

Capt. Bob Geis of the Naval Air Station Oceana said laser strikes make landing particularly dangerous.

“It’s a busy phase of flight for the pilot, so distractions at this time are particularly bad,” Geis said.

He sees the new law as an opportunity to spread the word about a practice that “can be blinding either temporarily or permanently.”

Many people like Willingham may not know the full danger of laser strikes for pilots, Geis said. He said Willingham “was very apologetic; he didn’t have any idea how much damage he would cause with the laser he had. He was just goofing around and had no idea of the magnitude of what would happen.”

Willingham is scheduled to be sentenced Friday. He faces up to 20 years in prison. He is hoping for a lighter sentence because of his apology and his cooperation with authorities.