Democratic Sen. Sheldon Whitehouse, sponsor of the amendment, said he was responding to a surge in incidents in which people have pointed at aircraft powerful lasers capable of temporarily blinding pilots.
The Federal Aviation Administration says the number of incidents in which people pointed lasers at planes and helicopters nearly doubled last year, from 1,527 in 2009 to 2,836 in 2010. FAA Administrator Randy Babbitt has said that in some instances pilots have had to relinquish control of their aircraft to other pilots because they could not see.
"This is a national security threat," Democratic Sen. Jay Rockefeller said. "As the technology increases, it's going to blind pilots permanently. Maybe if they're accurate, they blind both the pilot and co-pilot. ... There will be a future for terrorists in this business."
The amendment was approved on a 96-1 vote. Republican Sen. Rand Paul was the only senator to vote against the proposal.
"I think that it is a bad idea to point lasers at pilots and there are a lot of states that already have laws" against doing that, Paul said. "I think the states ought to take care of it."
A similar proposal has been introduced in the House of Representatives.
The rise in incidents has coincided with a growing hobbyist market for hand-held lasers that are far more powerful than the typical laser pointer and potentially dangerous. At the same time prices have dropped. Lasers that once cost more than $1,000 can now be bought online for a few hundred dollars or less.
Dozens of people in the United States and around the world have been arrested for pointing lasers at aircraft cockpits, most often near airports during takeoffs and landings. Those are the most critical phases of flight, when pilots need to be their most alert.
In some cases authorities have described the laser pointings as malicious acts. But in others, laser enthusiasts have said they did not realize the lasers could cause harm at seemingly long distances. Hobbyists often use the lasers at night when they are most visible against the night sky.
Interference with commercial airlines already is a federal crime. Current law has a gap, however, that weakens the FBI's ability to investigate laser incidents involving helicopters, said Dave Joly, a spokesman for the FBI in Denver, where 38 laser incidents were reported last year. The law covers mass transportation, but helicopters aren't considered mass-transit aircraft, Joly said.
There have been many instances of lasers pointed at helicopters, including police helicopters. Helicopters are especially vulnerable because they fly at lower altitudes than planes.
The vote makes the amendment part of a bill pending before the Senate to authorize FAA programs for the next two years. It also would speed up the FAA's transition from an air traffic control system based on World War II-era radar technology to one based on satellite-based technology.
The Senate also rejected an amendment by Republican Sen. Roger Wicker, R-Miss., that would have exempted FAA programs from a federal law that requires government contractors to pay construction workers the prevailing local wage.
Associated Press writers Dan Elliott in Denver and Laurie Kellman in Washington contributed to this report.