{"operation":"document","citation":"25-0120","title":"Southwest Airlines Co. — Hazardous Materials Safety Interpretation","source_type":"guidance","agency":"Pipeline and Hazardous Materials Safety Administration","status":"guidance","official":true,"published_on":"2026-02-23","effective_on":null,"summary":"25-0120 response to Southwest Airlines Co. concerning 175.10.","machine_formats":{"json":"https://regulus.evalyn.ai/document/phmsa-interpretation-25-0120.json","markdown":"https://regulus.evalyn.ai/document/phmsa-interpretation-25-0120.md"},"app_url":"https://regulus.evalyn.ai/document/phmsa-interpretation-25-0120","source_url":"https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/2026-02/250120.pdf","body":"<<<PAGE 1>>>\n\n1200 New Jersey Avenue, SE\nWashington, DC 20590\nU.S. Department\nof Transportation\nPipeline and Hazardous\nMaterials Safety\nAdministration\nFebruary 23, 2026\nTodd Hargrove\nHazardous Materials Program Manager\nSouthwest Airlines Co.\nP.O. Box 36611\nDallas, Texas 75235\nReference No. 25-0120\nDear Mr. Hargrove:\nThis letter is in response to your August 29, 2025 email requesting clarification of the Hazardous\nMaterials Regulations (HMR; 49 CFR Parts 171-180) applicable to battery-powered heat-\nproducing devices. Specifically, you ask about the on-board use (i.e., use aboard a passenger\naircraft) of a lithium ion battery-powered food warmer in the context of battery-powered heat-\nproducing devices subject to § 175.10(a)(14).\nWe have paraphrased and answered your questions as follows:\nQ1. Is a lithium ion battery-powered food warmer considered to be a portable electronic\ndevice rather than a heat-producing device?\nA1. Yes. It is the opinion of this Office that if the lithium-ion battery-powered device does\nnot generate an amount of heat sufficient to be a source of ignition, it is not a “heat\nproducing device” subject to § 175.10(a)(14). However, it should be considered a battery-\npowered device that would be subject to the requirements of § 175.10(a)(18) as a\n“portable electronic device.”\nQ2. Does § 175.10(a)(14) prohibit a passenger or crewmember from using a lithium-ion\nbattery-powered food warmer that is intentionally activated to warm food during flight?\nA2. Yes. However, for electronic devices subject to § 175.10(a)(18), use during flight is\nallowed when the device is for personal use. Whereas § 175.10(a)(14) requires the\nheating element, battery, or other component to be isolated to prevent unintentional\nactivation. Furthermore, battery powered heat-devices subject to § 175.10(a)(14) may not\nbe intentionally activated in flight.\n\n<<<PAGE 2>>>\n\nNote also that in addition to the HMR requirements, passengers and air carriers must\ncomply with all applicable Federal Aviation Administration (FAA) requirements. This\nincludes using safety management system (SMS) processes and coordination with\nrespective certificate management offices (CMO), as well as complying with 14 CFR\n§ 91.21 requirements that address operation of portable electronic devices aboard the\naircraft and the possible effects to aircraft systems. Information and guidance to assist\nwith compliance of this requirement can be found in Advisory Circular (AC) 91.21-1D,\ntitled “Use of Portable Electronic Devices Aboard Aircraft.” For additional information\nregarding the FAA requirements contact the FAA’s Office of Hazardous Materials Safety\nat hazmatinfo@faa.gov.\nI hope this information is helpful. Please contact us if we can be of further assistance.\nSincerely,\nDirk DerKinderen\nChief, Standards Development Branch\nStandards and Rulemaking Division\n\n<<<PAGE 3>>>\n\nSouthwest Airlines Co.\nTodd Hargrove\nSafety & Security\nPO Box 36611\nDallas, Texas 75235\nPhone:469-603-4813\nCasey, C.\n25-0120\nAugust 29, 2025\nPipeline and Hazardous Materials Safety Administration\nStandards and Rulemaking Division\nATTN: PHH-10\nU.S. Department of Transportation\nEast Building\n1200 New Jersey Avenue, SE\nWashington, DC 20590-0001\nRe: Interpretation Letter Request\nI am writing to obtain clarification regarding the acceptance of a battery powered heat-producing\ndevice and onboard use based on 49 CFR Part 175.10(a)(14)\nA prior interpretation letter (10-0267) mentioned a heat-producing device would be one that\nproduced an amount of heat sufficient to be a source of ignition. 175.10 also mentions unintentional\nactivation. The below questions are regarding a food warmer that would not produce enough heat\nto be a source of ignition and would be intentionally activated.\nWould a lithium-ion battery operated food warmer be considered a portable electronic device?\nWould 175.10(a)(14) prohibit a passenger or crewmember from using a lithium-ion battery operated\nfood warmer that is intentionally activated to warm their food during flight?\nThank you for your assistance in this matter. Feel free to contact me at Todd.Hargrove@wnco.com\nor 469-603-4813 if further clarification is needed.\nSincerely,\nTodd Hargrove\nHazardous Materials Program Manager\n\n<<<PAGE 4>>>\n\nAddressee Name\n2\nLetter Date","truncated":false,"body_characters":4282}