The federal government wants to facilitate the use of “highly automated” systems for transporting hazardous materials by air, water, and land (highways and rail). Most recently, on December 4, 2025, the Pipeline and Hazardous Materials Safety Administration (PHMSA) issued an Advanced Notice of Proposed Rulemaking (ANPRM) seeking stakeholder input on revisions to its Hazardous Materials Regulations (HMR), 40 CFR Pts. 171–80, needed to enable the use of unmanned drones, trucks, locomotives, and vessels to transport hazardous materials. Comments on the ANPRM are due March 4, 2026.
This follows the release of joint PHMSA—Federal Aviation Administration (FAA) guidance on “Transporting Hazardous Materials by Unmanned Aircraft Systems (UAS),” on November 19, 2025. Written comments on the guidance should be submitted by December 19, 2025.
These rulemakings are opportunities to shape the next HMR, its related guidance, and both agencies’ internal policies. Drone, truck, rail, and water-vessel operators, as well as their customers and stakeholders throughout the transportation supply chain, should consider preparing comments. The guidance does not apply to drone pesticide applications subject to regulation as “Agricultural Aircraft Operations” under Part 137 or to small UAS under Part 107.
Background
As transportation technologies rapidly advance, both Congress and the Executive Branch have recognized the need to strike a balance between automation’s huge economic opportunities and potential public safety risks. PHMSA’s ANPRM emphasizes that it works closely with its “modal partners” in implementing and considering changes to the HMR, including FAA, Federal Railroad Administration, Federal Motor Carriers Safety Administration, and the U.S. Coast Guard.
With respect to aviation, Section 933 of the 2024 FAA Reauthorization Act directed the U.S. Department of Transportation (DOT) to take a risk-based approach in developing a regulatory scheme needed approve UAS transport of hazardous materials. The Trump administration has pushed for regulations to incentivize the expansion of drone operations, issuing the June 2025 Executive Order and FAA’s August 7, 2025 proposed rulemaking, “Normalizing Unmanned Aircraft Systems Beyond Visual Line of Sight Operations” (“BVLOS”). The UAS Guidance and the ANPRM build on these initiatives, specifically with respect to facilitating drone transport of hazardous materials.
PHMSA ANPRM
The ANPRM extends the effort to facilitate the transport of hazardous materials using unmanned technologies to U.S. water, rail, and highway systems as well. The ANPRM signals PHMSA is considering potential revisions to the HMR for highly automated transportation systems, including changes to the HMR requirements relating to shipping papers and emergency response information, hazard communication, training, security plans and in-depth security training, packaging, and loading and unloading. PHMSA presents a number of “general questions” and “economic questions,” as well as rail, air, vessel, and highway-specific questions. Many questions refer to specific regulatory provisions.
The ANPRM also emphasizes that any person currently unable to comply with the HMR can request relief via 49 CFR Part 107 Subpart B’s Special Permit process. Anticipating the continued need for this process, even if changes are made to the HMR, PHMSA also requests input on whether changes to the Special Permitting process are unnecessary.
The deadline to comment on PHMSA’s ANPRM is March 4, 2026.
UAS Guidance
In their November 19 guidance, FAA and PHMSA propose a compliance framework based on stakeholder input provided at a public meeting held on August 22, 2024.
The guidance document covers five categories of information:
- The existing meaning of “hazardous materials,” currently defined as “any substance or material that the Secretary of Transportation has determined is capable of posing an unreasonable risk to health, safety, and property when transported in commerce, and is subject to the Hazardous Materials Regulations (HMR) codified in 49 CFR parts 171– 180”;
- Good practices for drone operations to transport hazardous materials, detailing the requirement to obtain an air carrier operating certificate under 14 CFR part 135 from FAA and comply with all applicable requirements of the HMR—Agricultural Aircraft Operations excluded;
- Existing risks and mitigation measures, including guidance on incorporating hazardous materials-related risk in UAS operator’s Safety Management System (“SMS”) process under 14 CFR § 5.1(b);
- DOT special permits, stating “UAS operators that meet all requirements of the HMR (49 CFR parts 171–180) are not required to obtain a DOT special permit. However, any UAS operator that cannot meet a specific HMR requirement because of the nature of its UAS operations or for any other reason must first be granted a DOT special permit by PHMSA before transporting hazardous materials pursuant to 49 CFR Part 107 Subpart B.
Businesses interested in using or expanding their use of UAS have until December 19, 2025, to submit comments on the FAA/PHMSA guidance document.
Outlook and Next Steps
Hazardous materials transporters interested in highly automated, unmanned systems—such as semitrucks, watercraft, or any sort of robot—should focus on the PHMSA’s HMR rulemaking. Transporters looking to develop or expand drone operations should also monitor FAA guidance too.
UAS operators should draft safety risk management assessments, consistent with the new guidance document. Performing safety risk assessments will help clarify whether operations will need DOT special permits. Those operating UAS for agricultural purposes may want to file comments encouraging the agencies to consider guidance specific to 14 C.F.R. § 137.3, the rules governing agricultural UAS operations, because the guidance does not currently apply to “Agricultural Aircraft Operations.”
Customers of hazardous material transporters and others involved in the industry should also consider the potential impact of changes to the HMR. For example, manufacturers should consider the impact of potential changes to packaging and hazard communication requirements.
Again, the deadline to comment on the FAA/PHMSA guidance document is December 19, 2025.
The deadline for comments on PHMSA’s ANPRM is March 4, 2026.