equipped with laser gas detection equipment made numerous
low-altitude passes over the Monterey Peninsula last weekend,
prompting complaints about its noise and quite a few different
theories about what it was up to — everything from searching
for drug smugglers for the DEA, to conducting mapping
surveillance for the NPS.
The mission of the helicopter turned out to be something never
seen before in these parts: It was searching for possible
leaks from gas mains through the Monterey Peninsula.
“We are flying for PG&E, doing leak surveys on their
pipelines,” said Winston Johnson, CEO of Lasen Technology of
Las .Cruces, NM. “We’ll be flying over 25,000 miles of pipe,
which includes most of the high-pressure lines PG&E has in
The utility stepped up leak detection after the San Bruno
disaster in September 2010, when a high-pressure gas main
through a residential neighborhood exploded, killing eight
people and destroying 38 homes.
“They’re being very proactive about leak detection, and we’re
helping them do that,” said Johnson.
His company’s helicopter is equipped with a laser tuned to the
frequency of methane gas, he said. As the helicopter flies
over the route of a gas main, the laser, mounted on the
helicopter’s belly, bounces back from the terrain below but is
partially absorbed if it encounters even very low levels of
methane. The reflected laser is picked up and measured by
sensors on the helicopter and matched with GPS data, producing
a map of any possible leaks.
“Using helicopters is just another tool in our toolbox to
identify any leaks and make repairs as quickly as possible,”
said PG&E spokesman Monica Tell.
She said the company’s pipeline network includes everything in
the state from Bakersfield to the Oregon border, and that
surveys would be made throughout the network six times a year.
The helicopter did not detect any leaks last weekend, but will
be back over the Monterey Peninsula in December, she said.
Concern about the chopper was heightened because it was flying
just a few hundred feet above the ground, but the low altitude
is necessary for the laser detection equipment to work.
don’t fly higher than 500 feet,” Johnson said.
Even at that low altitude, the laser is safe for people on the
ground, according to Johan Wictor, who is with Pergam
Technical Services, which also does helicopter gas leak
detection for many of the nation’s largest gas companies.
“You can not see the laser, and it does not burn you,” he
His company also records visual images of pipeline routes,
which allows companies to keep an eye out for erosion,
poachers and other problems that could affect pipeline safety.
ÅAnd, despite the occasional noise complaint, “when we
tell them what we are doing, most people are comfortable with
that,” Johnson said.
According to Tell, the helicopter laser detection is so
sensitive, it will help keep gas leaks from becoming
dangerous, as the one in San Bruno did.
“We can pick up concentrations as low of five parts per
million,” Johnson said.
Natural gas isn’t considered explosive unless it is
at least 5,000 ppm in an enclosed space,
according to Prasad Saurabh, a professor of epidemiology and
community health at the University of Ottawa.
The equipment is so sensitive, it also picks up other sources
of methane. “If we fly over a farm, I can assure you the laser
is going to see the cows,” Johnson said.
To see a map of local gas mains, go to