FMCSA Part 392 covers what Part 395 doesn't — how the commercial motor vehicle must actually be operated once the driver is behind the wheel. Ill or fatigued operator (392.3), alcohol (392.5), schedules that conform to speed limits (392.6), pre-drive check (392.7), cargo securement (392.9), hazardous weather (392.14), seat belts (392.16), no texting (392.80), no handheld phone (392.82). Every violation feeds the Unsafe Driving BASIC. This 2026 guide walks the framework by driver decision moments. Book a demo .
Part 392 by the Decisions Drivers Make
Part 392 is broad. But every rule maps to one of four decision moments on a shift. Understand the moments, understand the rules.
Part 395 gets more attention because HOS violations produce the most-visible out-of-service orders. Part 392 quietly does more day-to-day damage: seat belt tickets, handheld phone citations, speeding citations, and hazardous-conditions violations pile up in the Unsafe Driving BASIC across dozens of drivers per year on any mid-size fleet. Individually each is a small event; collectively they push the carrier over CSA intervention thresholds and generate the audits that drain compliance staff time. Understanding Part 392 as a driver decision framework — not a wall of regulations — is what separates fleets that stay under intervention thresholds from those that don't.
Before driving: the 5 pre-shift decisions Part 392 requiresSections 392.3 through 392.9 — the checks that happen before wheels turn
Every driver signs the DVIR and moves the vehicle only after clearing five federal pre-shift requirements. Skipping any one is a violation before the shift technically starts. Book a demo to see the pre-shift compliance workflow in HVI
Fitness to drive (§ 392.3)
No driver shall operate a CMV while their ability or alertness is so impaired by fatigue, illness, or other cause as to make it unsafe to begin or continue operating. FMCSA guidance: only the driver can make this determination. Coercion by carriers to override is prohibited under 49 CFR 390.6.
Drug & alcohol prohibition (§§ 392.4, 392.5)
No CMV operation while under the influence of controlled substances (392.4). No alcohol consumption within 4 hours of driving, no possession of alcohol in the CMV, no operation with any measurable alcohol concentration (392.5). Confirmed-positive test = immediate removal from safety-sensitive function per 49 CFR Part 382.
Schedules must conform to speed limits (§ 392.6)
Motor carrier cannot dispatch a schedule that would require the driver to exceed posted speed limits to complete. This is the section that flips liability from driver-alone to driver + carrier when schedule pressure produces speeding violations. Documentation of realistic run times matters.
Equipment inspection (§§ 392.7, 392.8)
Driver must be satisfied 15 categories of vehicle parts/equipment are in good working order before driving: service brakes, parking brake, steering, lights/reflectors, tires, horn, wipers, mirrors, coupling, wheels/rims, emergency equipment (392.8). This is the pre-trip inspection Part 392 mandates, distinct from the DVIR filed under Part 396.
Cargo securement inspection (§ 392.9)
Cargo distribution, securement, and dunnage inspected before dispatch and re-inspected within the first 50 miles. Additional re-inspection whenever cargo is changed, added, or removed, or after a 3-hour or 150-mile driving segment (whichever occurs first). Missed re-checks are a common Part 392 citation.
During driving: the behavioral rules that generate the most citationsSpeeding, seat belt, phone — all feed the Unsafe Driving BASIC
Once the vehicle is moving, Part 392 governs how it's operated. These four behavioral rules produce the majority of Unsafe Driving BASIC violations at roadside, and each carries specific severity weight in the CSA methodology.
Speed and local traffic law
CMV must be operated in accordance with the laws, ordinances, and regulations of the jurisdiction it's operating in — unless FMCSA imposes a stricter standard, in which case FMCSA wins. Speeding, following too closely, improper lane changes all land here.
Seat belt required
Driver and all occupants of a property-carrying CMV must be properly restrained by the seat belt assembly whenever the vehicle is in operation. Driver must not permit operation without occupants belted. Most-cited "small" Part 392 violation.
No texting while driving
Complete prohibition on texting while operating a CMV. Texting means manually entering alphanumeric text into, or reading text from, an electronic device. Applies at all times the CMV is being operated on a public road.
No handheld mobile phone
Prohibition on using a handheld mobile telephone while operating a CMV. Hands-free devices permitted only if driver can activate/deactivate with a single button and phone is located where driver can operate it without leaving their seated driving position.
Tracking pattern behavior across drivers is where documentation platforms earn their keep. Book a demo to see driver-level pattern tracking in HVI
Hazardous conditions: what § 392.14 actually requiresThe section that puts the discontinue-operation decision with the driver, not dispatch
Section 392.14 is one of the most important pieces of Part 392 for fleet operations because it explicitly assigns the safety judgment to the driver, not dispatch or management. FMCSA guidance under this section is unambiguous: only the driver can determine if conditions have become sufficiently dangerous to require discontinuing operation. This is what protects drivers from coercion and protects carriers from vicarious liability when a driver correctly refuses to operate in unsafe weather. Start a free trial and document weather-related discontinue decisions with searchable records.
Extreme caution — the standard
The rule: "Extreme caution in the operation of a commercial motor vehicle shall be exercised when hazardous conditions, such as those caused by snow, ice, sleet, fog, mist, rain, dust, or smoke, adversely affect visibility or traction."
Speed reduction required
"Speed shall be reduced when such conditions exist." Posted speed limit is the ceiling, not the target. Roadside inspectors and post-crash investigators evaluate whether reduction was reasonable for the observed conditions.
Discontinue operation when dangerous
"If conditions become sufficiently dangerous, the operation of the commercial motor vehicle shall be discontinued and shall not be resumed until the commercial motor vehicle can be safely operated."
Who decides: the driver
FMCSA published guidance is direct: "the driver is clearly responsible for the safe operation of the vehicle and the decision to cease operation because of hazardous conditions." Carrier cannot compel continued operation.
Coercion prohibited (§ 390.6)
Motor carriers, shippers, receivers, and transportation intermediaries are prohibited from coercing drivers to operate CMVs in violation of federal safety rules. Coercion complaints filed with FMCSA generate investigation.
Documenting the driver's discontinue-operation decision, the weather conditions, and the dispatch communication protects both the driver and the carrier if the call is later questioned. Book a demo to see hazardous-condition event documentation in HVI
From a fleet safety director on Part 392 pattern management
Our Unsafe Driving BASIC crept up over three quarters and I couldn't figure out why — no crashes, no major violations. When I finally pulled the citation detail, it was death by a thousand cuts: seat belt tickets across 6 drivers, three handheld phone citations, four speeding-in-a-work-zone violations, a couple of railroad grade crossing slowdown misses. Every single one was Part 392. None of them individually felt like a big deal to the drivers involved.
We built a monthly Part 392 pattern review — every citation reviewed with the driver, root cause documented, corrective action assigned and tracked. Standardized the pre-trip checklist to include seat belt policy acknowledgement, phone-storage protocol, and hazardous-conditions authority reminder. Score dropped back under threshold in two quarters. The rules didn't change; our attention to the pattern did.
Frequently asked questions
What is FMCSA Part 392 and what driving rules does it cover?
FMCSA Part 392 (49 CFR Part 392) is the federal rulebook covering the driving of commercial motor vehicles — how the CMV must be operated on the road once the driver is behind the wheel. Part 392 covers ill or fatigued operator prohibition (§ 392.3), drug and alcohol prohibition (§§ 392.4, 392.5), the requirement that carrier schedules conform to speed limits (§ 392.6), pre-drive equipment inspection (§ 392.7), cargo securement inspection (§ 392.9), railroad grade crossing requirements (§§ 392.10, 392.11), hazardous weather conditions requiring extreme caution (§ 392.14), mandatory seat belt use (§ 392.16), emergency signals when stopped (§ 392.22), fueling precautions (§§ 392.50, 392.51), texting prohibition (§ 392.80), and handheld mobile phone prohibition (§ 392.82). Violations feed the Unsafe Driving BASIC in the CSA scoring system — one of the two most heavily-weighted CSA categories.
Who decides when weather is too dangerous to continue driving under Part 392?
The driver decides — not dispatch, not the safety manager, not the customer. Section 392.14 requires extreme caution when hazardous conditions (snow, ice, sleet, fog, mist, rain, dust, smoke) adversely affect visibility or traction, requires speed reduction when such conditions exist, and requires operation to be discontinued when conditions become sufficiently dangerous. FMCSA published guidance under this section states directly: "the driver is clearly responsible for the safe operation of the vehicle and the decision to cease operation because of hazardous conditions." This assignment protects drivers from being coerced by carriers, customers, or dispatchers to continue operating in unsafe conditions. Separately, 49 CFR 390.6 prohibits motor carriers, shippers, receivers, and transportation intermediaries from coercing drivers to violate federal safety rules — coercion complaints can be filed with FMCSA and generate investigation.
What are the mobile phone and texting rules under Part 392?
Two separate prohibitions. Section 392.80 prohibits texting while operating a CMV — defined as manually entering alphanumeric text into, or reading text from, an electronic device. Section 392.82 prohibits using a handheld mobile telephone while operating a CMV; hands-free devices are permitted only if the driver can activate/deactivate with a single button and the phone is located where the driver can operate it without leaving the seated driving position. Both prohibitions apply at all times the CMV is being operated on a public road. Each violation carries maximum severity in the Unsafe Driving BASIC (10 CSA severity points). Repeat texting or handheld phone violations can trigger driver disqualification review under 49 CFR Part 383. From an operational standpoint: mounted phones with hands-free operation are compliant; phones held to the ear, dialed manually, or used for texting are not.
Does the carrier share liability for Part 392 violations by drivers?
Yes — and the pattern matters more than any single violation. Part 392 citations attach to both the driver's personal safety profile AND the carrier's CSA score in the Unsafe Driving BASIC. Individual citations from one driver hit that driver's Pre-Employment Screening Program (PSP) record and are visible to future employers for three years. The same citations aggregate across all the carrier's drivers into the carrier's Unsafe Driving BASIC score — a threshold of roughly 65 percentile triggers FMCSA intervention (audits, warning letters, focused reviews). Additionally, if the carrier schedules loads in ways that require speeding to complete (§ 392.6), the carrier bears direct responsibility for the resulting violations, not just the driver. Some fleets absorb Part 392 costs unnecessarily because they don't manage the pattern — individual citations feel small until the cumulative CSA impact becomes visible.
Does HVI provide Part 392 driver safety and compliance management?
HVI supports standardizing driver safety processes, documenting training and policy acknowledgements, maintaining searchable compliance records, tracking corrective actions on flagged behaviors, and connecting driver safety documentation with inspection workflows. HVI is not a real-time telematics or in-cab camera system — behavioral capture during driving (speeding events, harsh braking, phone use detection, following distance monitoring) comes from telematics and video providers (Samsara, Motive, Lytx, Netradyne, and others). What HVI does is organize the documentation side of Part 392 compliance: policy acknowledgements, training completion records, corrective action tracking on citations, pre-trip inspection records that include Part 392 pre-drive checks under §§ 392.7 and 392.9, and searchable driver-level compliance history. Your telematics platform captures the event; HVI is where the documentation trail lives.
Give your safety team the Part 392 documentation layer
HVI supports driver training records, policy acknowledgements, corrective action tracking, pre-trip inspection records including Part 392 pre-drive checks, and searchable compliance history at the driver level. In-cab behavioral capture (speeding, phone use, harsh braking) comes from telematics and video providers. HVI is the documentation layer that supports your Part 392 program when CSA scores need context or FMCSA audits ask for records.
No credit card · No hardware · Compliance documentation ready on day one
