Interpretation Response #25-0120

Below is the interpretation response detail and a list of regulations sections applicable to this response.

Interpretation Response Details

Response Publish Date: 02/23/2026

Company Name: Southwest Airlines Co.

Individual Name: Todd Hargrove

Location State: TX Country: US

View the Interpretation Document

Response text:

February 23, 2026

Todd Hargrove
Hazardous Materials Program Manager
Southwest Airlines Co.
P.O. Box 36611
Dallas, Texas 75235

Reference No. 25-0120

Dear Mr. Hargrove:

This letter is in response to your August 29, 2025 email requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) applicable to battery-powered heat-producing devices. Specifically, you ask about the on-board use (i.e., use aboard a passenger aircraft) of a lithium-ion battery-powered food warmer in the context of battery-powered heat-producing devices subject to § 175.10(a)(14).

We have paraphrased and answered your questions as follows:

Q1. Is a lithium ion battery-powered food warmer considered to be a portable electronic device rather than a heat-producing device?

A1. Yes. It is the opinion of this Office that if the lithium ion battery-powered device does not generate an amount of heat sufficient to be a source of ignition, it is not a "heat producing device" subject to § 175.10(a)(14). Rather, it should be considered a battery-powered device that would be subject to the requirements of § 175.10(a)(18) as a "portable electronic device."

Q2. Does § 175.10(a)(14) prohibit a passenger or crewmember from using a lithium ion battery-powered food warmer that is intentionally activated to warm food during flight?

A2. Yes. If the food warmer were to be subject to § 175.10(a)(14), it would require the heating element, battery, or other component to be isolated to prevent unintentional activation. Furthermore, battery-powered heat-producing devices may not be intentionally activated in flight. However, as noted in answer A1, the device is considered a portable electronic device subject to § 175.10(a)(18) which allows for personal use during flight.

Note also that in addition to the HMR requirements, passengers and air carriers must comply with all applicable Federal Aviation Administration (FAA) requirements. This includes using safety management system (SMS) processes and coordination with respective certificate management offices (CMO), as well as complying with 14 CFR § 91.21 requirements that address operation of portable electronic devices aboard the aircraft and the possible effects to aircraft systems. Information and guidance to assist with compliance of this requirement can be found in Advisory Circular (AC) 91.21-1D, titled "Use of Portable Electronic Devices Aboard Aircraft." For additional information regarding the FAA requirements contact the FAA's Office of Hazardous Materials Safety at hazmatinfo@faa.gov.

I hope this information is helpful. Please contact us if we can be of further assistance.

Sincerely,

Dirk DerKinderen
Chief, Standards Development Branch
Standards and Rulemaking Division

§ 91.21, § 175.10(a)(14), § 175.10(a)(18)

Regulation Sections