A safety alert issued by the Federal Aviation Administration last week warns that several airlines and flight attendants have reported coffee filter packages bursting in-flight, causing first- and second-degree burns to crew members and bystanders.
The mishaps occur while the hot beverage is brewing in drip-style coffee makers on board, apparently caused by a pressure build-up in the filter package. Warning signs include water overflow and "a hissing noise," the FAA said.
"When the coffee pot handle is lifted, the coffee filter containing the hot coffee grounds can burst causing burns to the face, neck, hands, arms and torso in varying degrees of severity," the safety alert notes.
The government advises crews to make sure the packages are not folded and to use only one filter per pot.
If the water begins to overflow from the basket or makes a hissing sound, flight attendants should step aside, not raise the handle and turn off the unit, the FAA counsels.
Longtime flight attendant Heather Poole said she's heard about the problem, but she's never seen a filter "explode" and doesn't know anyone hurt in such a mishap.
"We're taught how to insert the bag so that it doesn't happen," said Poole, the author of "Cruising Attitude: Tales of Crashpads, Crew Drama, and Crazy Passengers at 35,000 Feet."
She added that the most common issue with coffee filters in flight is that they break - not violently burst - which means the grounds get into the water, so the flight attendant must clean out the pot and start anew. Even that simple added step can disrupt a crew's tightly choreographed routine on a plane.
"It takes a little extra time to clean out a coffee pot in the galley because our water trickles out," Poole said.
"It also seems like it takes forever to brew when passengers on morning flights want their coffee now, now, now."
Still, the bursting coffee filters are enough of a concern that the FAA is encouraging airlines to add "cautionary instructions and procedures" to the Flight Attendant Manual and training program, warning crew members of the dangers to people and equipment.
(Copyright © 2013 NBC Universal, All Rights Reserved)