The FAA has issued a safety information bulletin related to the new security bans on most personal electronics in carry-on bags on certain flights, but is not making that bulletin public, Aviation Daily sister publication Air Transport World has learned.

An FAA spokesperson confirmed April 7, in emailed responses to ATW questions, that the agency issued the bulletin when the U.S. Homeland Security Department (DHS) implemented its ban on passenger personal electronic devices (PEDs) larger than smartphones in the cabin on direct flights from 10 airports—most of them in the Middle East—to the U.S.

The ban, introduced in March, was followed by a similar security rule by the UK government, although the UK ban applies to direct flights to the UK from six countries, and the affected airports do not align with the U.S. list.

U.S. government officials, when briefing media March 20 on the new rules, said they were aware of fire-safety concerns that the new rules raise because they lead to larger numbers of lithium battery-powered PEDs being loaded into the cargo holds of affected airlines. Officials said they were “coordinating very closely” with the FAA about how to implement the new security rules while maintaining aircraft safety.

But the FAA’s April 7 response indicates the agency did more than coordinate and advise; it issued a safety bulletin at the time of the ban.  “The FAA issued a safety bulletin when DHS made the original announcement. The EASA and ICAO bulletins were based on language in the original FAA bulletin,” the spokesperson said. That is a reference to subsequent bulletins from ICAO and the European Aviation Safety Agency. The EASA bulletin, issued earlier this week, describes PEDs as “dangerous goods” in the cargo hold. “Certain precautions should therefore be observed to mitigate the risk of accidental fire in the cargo hold. In particular, PEDs placed in checked baggage must be completely switched off and well protected from accidental activation,” the EASA said.

A U.S. aviation safety advocacy organization also joined those agencies in raising concerns about potential fire hazard risks caused by the U.S. and UK bans. The Washington-based Flight Safety Foundation (FSF), an independent, nonprofit, international organization, issued a statement warning that the bans “significantly increase the number of PEDs carried in cargo holds,” and urged the industry to “fully consider the consequential risk” associated with that change.

“There have been occasions when the lithium batteries in PEDs have suffered thermal runaway and caught fire. To mitigate this risk, cabin crew have been trained in how to manage these situations. With the transport of PEDs on certain flights now restricted to the cargo hold, along with other potentially flammable items within checked-in baggage, a known and managed risk has effectively been transferred to another part of the aircraft where, should thermal runaway occur, it is rendered inaccessible to cabin crew,” the FSF said.

Like the EASA, the FSF emphasized that devices placed in checked baggage must be powered off; be protected from accidental activation; and be protected from damage, but added: “The risk, however, that some of these items may be left on cannot be overlooked.”