Sandia finds fix for planes' false alarms

Nothing goes wrong on 199 airplanes every year.

But all 199 of them have something in common with one plane that
does have a problem. They've all given pilots scary warnings that a
cargo fire is spreading.

That ratio - 199 false alarms out of about 200 each year - is
unacceptable, costly and dangerous, officials say.

So NASA and the Federal Aviation Administration asked Sandia
National Laboratories to help them do something about it.

"Any time an airplane declares an emergency and has to land where it
didn't intend to, there's a risk," said Dave Blake, a manager at the
Fire Safety Section of the FAA Technical Center in New
Jersey. "There are a lot of consequences to false alarms. Often
planes have to recharge fire suppression systems, re-pack emergency
slides. It's stress on passengers, and it takes a lot of time."

To understand why there are so many false alarms and strategize
about a way to fix them, Sandia engineers designed a computer model
of the insides of standard airplane cargo holds. It simulates how
fire spreads through those areas and suggests locations for smoke
detection systems, said Jill Suo-Anttila, part of the Sandia team.

"False alarms are usually responding to something, like gas, dust or
particles. It's not usually the electronics," Suo-Anttila said. "Our
model has already been released to a small number of people in the
airline community, and they're using it to design and certify their
fire detection system arrays before testing them in the air."

The work will also help NASA design better smoke detectors for
aircraft, Suo-Anttila said.

"NASA has created new multi-criteria fire detectors that look for
things like heat, smoke and concentrations of gas," she said. "This
should help them tweak the design."

The FAA and other regulatory agencies worldwide require all
passenger-carrying aircraft to be equipped with cargo area fire
detection systems. Those systems must go off within one minute of
the start of a fire.

The FAA is still verifying Sandia's model by doing test burns in
retired aircraft cargo holds on the ground, said Lou Gritzo, a
manager on the Sandia team.

It will also test the systems in the air, he added.

"Right now our model simulates conditions such as ventilation and
fire detector placement on two types of aircraft," Gritzo said. "But
certainly in conditions where the compartment size and shape is
similar, we could alter the model and use it to design systems for
those - things like other planes or possibly cargo containers."

Testing the systems in a computer model before testing them in an
airplane also saves airlines money, because it gives a baseline idea
of which fire detection strategies would be more successful, Gritzo
added.

"If you can test these in a model before taking them up in the air
for a test, boy it saves a lot of time," he said.

The final tweaking of the model will likely be finished within the
year, and after that, it will be given to commercial airliners and
other interested parties, Gritzo said.

"The reason Sandia is doing this is we have a long history of
supplying technology to the military as well as to civilian air
transportation," Gritzo said. "When the need arose, we were chosen
to work with NASA and the FAA because of our experience and
expertise in modeling and engineering."

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