Remember those exploding hoverboards, the once-popular self-balancing scooters that most airlines banned late last year due to their proven combustibility?

The problem with the hoverboards was pinned on their lithium ion batteries, which were also the culprits in a series of onboard fires that bedeviled early models of Boeing’s 787 Dreamliner.

In yet another instance of misbehaving batteries, the batteries powering Samsung Galaxy Note7 smartphones have been implicated in at least 35 cases of overheating and catching fire. Samsung has issued a recall for more than 2.5 million Galaxy 7s with the exploding batteries.

The matter has come to the attention of the Federal Aviation Administration, which has broad responsibility for safety in commercial aviation. Here’s the FAA’s statement:

In light of recent incidents and concerns raised by Samsung about its Galaxy Note 7 devices, the Federal Aviation Administration strongly advises passengers not to turn on or charge these devices on board aircraft and not to stow them in any checked baggage.

For now at least, the guidance on Galaxy Note 7s is a recommendation, not a rule, so there’s no penalty for ignoring the suggestion. If the FAA were to take the next step and add the phones to the list of items covered by its Hazardous Materials Regulations, passengers could be fined between $250 and $500,000 for non-compliance.

Samsung today released a statement acknowledging the FAA’s concerns and promising to “expedite new shipments of Galaxy Note7 starting from this week in order to alleviate any safety concerns and reduce any inconvenience for our customers.”

Both Samsung’s recall and the FAA’s recommendation are sensible and necessary, given the potential for fire onboard a commercial aircraft. But with 2.5 million phones packing the defective batteries, there remains the real possibility that some of the phones will find their way onto some flights. Not everyone is aware of the recall, after all, or of the FAA’s directive.

Reader Reality Check

Exploding smartphones: an alarming prospect, or just one among many on the list of your travel worries?

After 20 years working in the travel industry, and almost that long writing about it, Tim Winship knows a thing or two about travel. Follow him on Twitter @twinship.

This article first appeared on SmarterTravel.com, where Tim is Editor-at-Large.