(Bloomberg) -- As wildfires raged across California, mobile phones went silent as towers and lines succumbed to the flames.
“We had to drive through neighborhoods with sirens and public address systems to alert residents and visitors,” said David Katz, a spokesman for the Malibu Search and Rescue Team. “In some cases, we had to go house to house on foot.”
Those experiences during the widespread fires that claimed more than 70 lives -- as well as during and after hurricanes earlier this year -- reveal a downside to the wireless communications upon which Americans are increasingly dependent: Mobile service falls short of old-fashioned landlines when it comes to surviving catastrophic events.
That can leave citizens unable to receive automated warnings or call 911 for help.
“The current technology gives us ubiquity, but not great resiliency,” said Jamie Barnett, a partner at the Venable law firm and former chief of the Federal Communications Commission’s public safety bureau.
More than half of U.S. households -- and more than 70 percent of adults renting their homes -- rely on mobile phones, according to survey results from the U.S. Centers for Disease Control.
The devices are convenient, but can fail when a storm knocks down a cell tower, when batteries run down, and when the lines that carry phone calls from towers to the network are cut during recovery efforts.
There is no requirement for cell sites to have backup power. The industry has resisted efforts to make that mandatory, arguing that it would be overly burdensome in part because it can be expensive to rent space for equipment and hard to get permits to store fuel in some places.
Widespread service failures after Hurricane Michael in Florida last month brought criticism from the FCC, which is now reviewing phone companies’ performance.
President Donald Trump visited ravaged areas of California on Saturday and viewed the charred remains of burned-out homes during a visit accompanied by Governor Jerry Brown and Governor-elect Gavin Newsom. The president stressed common ground on how to approach the forest-fire problem, marking a change of tone from his previous criticism of the state’s Democratic leaders.
The largest mobile providers said they were working hard to restore service as soon as crews are able to access damaged areas.
“Overall, our network continues to perform well and is currently operating at more than 99 percent of normal in affected areas in Northern and Southern California,” said Jim Greer, an AT&T spokesman.
"Our wireless network has performed amazingly well throughout the devastating fire," said Howie Waterman, a Verizon spokesman.
In decades past, telephones at the end of copper lines could offer service, even during widespread electricity failures, if a nearby hub managed to have power, perhaps from a generator.
That’s not to say that arrangement is indestructible. For weeks after Hurricane Maria bombarded Puerto Rico last year, landline service was “generally non-existent,” according to an FCC report.
Cell phone service, too, was badly damaged but recovered faster, pointing to an advantage of mobile service: phone companies keep portable cell towers that they move into trouble zones when needed.
In California, the City of Malibu tweeted on Nov. 13 that AT&T Inc. and Verizon Communications Inc. were installing temporary towers. AT&T said it deployed eight truck-borne cell sites, including four in Malibu and three in Paradise.
Nevertheless, vulnerability increases as dependence on wireless phones grows. The number of wireless service outages reported to the FCC jumped to 1,079 in 2016 from 189 seven years earlier, according to the Government Accountability Office. Accidents such as damage to cables during construction work made up about three-fourths of the total, with almost all the remainder due to storms and fires, the agency said.
The GAO said network resiliency would be improved if there was a requirement for power backups at cell towers. It also listed possible disadvantages of such an approach: some cell sites, such as rooftops, might not be able to accommodate heavy backup gear, and power interruptions could outlast an emergency battery, or a generator’s fuel supply.
After Hurricane Michael swept through Florida last month, FCC Chairman Ajit Pai criticized what he called “slow progress” in restoring wireless service. Five days after the storm struck, 65 percent of cell sites in hard-hit Bay County weren’t working, according to agency figures. Pai ordered an investigation, which is continuing. Carriers defended their restoration efforts and offered free mobile service to some customers.
More recently, AT&T offered waivers of fees for some services for landline customers affected by three California fires. And some wireless providers have handed out free phones.
The vast majority of service interruptions in California were caused by underground fiber lines being burned, according to a Verizon spokeswoman. If fiber is carried on poles that burn down, then there will also be service interruption.
FCC commissioners who monitored efforts in Florida reported a sometimes-chaotic scene, with crews sent in to restore power lines and other utilities at times cutting fiber lines that support phone networks.
“Cuts during recovery and restoration are something that we see through every storm,” FCC Commissioner Brendan Carr said at a Nov. 15 news conference. “We have to do a better job of that, in addition to the broader questions of making sure the network itself survives the storm.”
After Hurricane Katrina devastated parts of the Gulf Coast in 2005, the FCC passed requirements for backup power for mobile phone sites. The wireless industry opposed the regulations in court and the FCC withdrew them.
After Superstorm Sandy pummeled the Northeast in 2012, the agency proposed issuing public data showing which carriers maintained post-storm service, and which didn’t. The industry objected and the FCC eventually withdrew the proposal, said David Turetsky, who backed the idea while serving as the agency’ public safety bureau.
The FCC agreed to voluntary steps proposed by the carriers in 2016 that calls for them to help each other, and to consult with localities. After disasters strike, the agency publishes data that shows what portion of a county’s cell sites are working, without specifying performance company-by-company.
“Providers take significant steps to maintain and restore service before, during and after disasters,” Scott Bergmann, senior vice president of regulatory affairs at CTIA, a telephone industry trade group, said in an email. “We continue to work closely with emergency response partners, including the FCC, on improvements to ensure consumers have wireless service when they need it most.”