The Two OOS Rates You're Not Reading Separately (And Why It Matters)

I'm going to tell you about two carriers. Both have a 20% OOS rate. I'd book one of them. I'd pass on the other.

The difference is which OOS rate is 20%.

FMCSA's safety data tracks out-of-service violations across two completely separate buckets: vehicle and driver. Most vetting tools either show you both numbers without explaining the distinction, or collapse them into a single blended figure and call it "OOS rate." Either way, brokers tend to look at one number, compare it to some vague internal threshold, and move on.

That's a mistake. Vehicle OOS rate and driver OOS rate predict different failure modes. Reading them together without understanding what each one means is like checking a patient's temperature and blood pressure and treating them as interchangeable.

What Each One Measures

Vehicle OOS rate is the percentage of inspections where an inspector found equipment defects serious enough to pull the truck out of service on the spot. Brakes below measurement threshold. Tires with exposed cord. Lights out. Steering with excessive play. The underlying violations trace back to 49 CFR Part 396, the inspection, repair, and maintenance regulations. Section 396.3 requires carriers to maintain equipment "in safe and proper operating condition at all times." Section 396.17 requires periodic annual inspections. When a carrier's vehicle OOS rate is high, their trucks are showing up to roadside inspections with defects that Part 396 required them to catch before the truck ever left the yard.

The national average vehicle OOS rate runs around 21 to 22 percent. That's not a reassuring number — one in five inspections nationally finds a defect serious enough to put the truck on the side of the road. If a carrier's rate is above that, their maintenance culture is worse than the industry average. Below it, better.

Driver OOS rate is different. That's the percentage of inspections where the driver — not the truck — gets put out of service. Driver OOS violations come from a narrower set of regulatory failures: hours-of-service violations under 49 CFR Part 395 (driving beyond the 11-hour limit, not taking required off-duty time, falsified or missing logs), missing or improper credentials under 49 CFR § 391.11 (the driver doesn't hold the right CDL class or endorsement for the load they're running), or controlled substance and alcohol testing flags under 49 CFR Part 382.

The national average driver OOS rate sits around 5 to 6 percent. About one inspection in twenty. Because this rate is naturally lower than the vehicle rate, a carrier that looks "average" at 10% is actually running nearly twice the national rate. A carrier at 15% driver OOS is running close to three times it. That's not statistical noise. That's a carrier whose drivers are routinely getting caught out of hours, or whose qualification files don't hold up when an inspector asks for credentials.

The Carrier That Made Me Pay Attention to This

A few years before I built DOTScreener, a colleague at the brokerage I was at booked a refrigerated load with a carrier — let me call them MC-2847163 / DOT-3948271. Good lane rates. Reasonably new equipment. Their vehicle OOS rate was 8%, well below average. Trucks looked clean.

But their driver OOS rate was 23%. We didn't catch it during vetting because the tool we were using showed a blended OOS rate, not the two figures separately. The blended number looked elevated but not disqualifying. So we booked.

Three weeks later, the same carrier was involved in a separate crash with a different broker. In discovery on that case, the plaintiff's lawyers pulled inspection records going back two years and showed exactly what we would have seen if we'd looked: a consistent pattern of drivers getting pulled out of service for HOS violations. Not equipment failures. Drivers. That carrier had clean trucks and a compliance culture problem at the driver level. The vehicle OOS rate was masking what was actually going on.

I'm not going to say that crash was caused by fatigue or hours fraud. I don't know. But I know that a 23% driver OOS rate — four times the national average — tells you something specific about how a carrier manages its drivers, and neither my colleague nor I had looked at that number.

When High Vehicle OOS Tells a Different Story

Flip the scenario. A carrier with a 35% vehicle OOS rate and a 3% driver OOS rate is a different problem. Their drivers are HOS-compliant and credentialed. Their equipment is deteriorating. That's a maintenance budget problem, or a PM-schedule problem, or a fleet age problem. The failure mode there is a brake component failing at highway speed, not a fatigued driver. Both are bad. But your T-call questions and your documentation strategy are completely different.

For a carrier with a high vehicle OOS rate, the questions are about maintenance. When did they last run internal DOT inspections? Do they require drivers to complete the pre-trip and post-trip inspection under 49 CFR § 396.13 — the regulation that requires a driver to review the previous driver's DVIR before operating the vehicle? What's their PM interval? Do they use a third-party inspection program?

For a carrier with a high driver OOS rate, the questions are about compliance culture. How do they handle HOS — are they on ELDs? How do they manage the Drug & Alcohol Clearinghouse requirements under 49 CFR Part 382, specifically the pre-employment query and the annual limited query every carrier is supposed to run? What happens when a driver hits their hours mid-load — do they have relief drivers available, or do they expect the driver to figure it out?

Those aren't the same conversation. The OOS rate split tells you which one to have.

A Note on Inspection Count

Before you panic over a 40% driver OOS rate, look at the inspection count. If a carrier has 5 inspections in the last 24 months and 2 of them resulted in a driver OOS, that's a 40% rate built on two data points. One driver having a bad month could do that. I'm not dismissing it — I still note it — but the statistical weight is very different from a carrier with 150 inspections at a 40% driver OOS rate.

SAFER shows you the inspection counts. Use them. A rate built on fewer than 10 inspections tells you something, but don't treat it the same as 100 inspections showing the same pattern. What you're looking for with a thin inspection history is whether the carrier is trending worse over time — a cluster of violations in the last six months after clean years is a different signal than scattered violations across a long history.

The inverse matters too: a carrier with 300 inspections and a 4% driver OOS rate has earned that number. Three hundred inspections is a large enough sample that 4% tells you something real about their driver management.

What "High" Means in Practice

I'll be specific because vague thresholds are useless for documentation.

Vehicle OOS rate: under 15% is clean. 15% to 25% is average or near-average — worth noting in the file but not a flag on its own. 25% to 35% means roughly one in three or four inspections is finding a defect that puts the truck out of service, and I want to ask about maintenance. Over 35%, I need a strong rationale to proceed, and that rationale goes in writing.

Driver OOS rate: under 5% is clean or below average. 5% to 10% is elevated and I note it. Over 10% — running roughly twice the national average — I'm asking direct questions on the T-call. Over 15% is nearly three times the national average and I need to hear something convincing from dispatch or safety before I tender.

These aren't bright-line rules from a regulation. They're the thresholds I've built from watching what comes up in discovery when claims go sideways, and from talking to defense lawyers about what plaintiffs' lawyers highlight when they're building a negligent selection case. A carrier at 18% driver OOS rate that the broker tendered to without even noting the number — that's what a plaintiff's lawyer calls "willful ignorance."

After Montgomery, the Documentation Stakes Are Higher

The Supreme Court's May 14, 2026 decision in Montgomery v. Caribe Transport II, LLC settled a split that had been protecting brokers in the 7th and 11th Circuits for years. The unanimous opinion held that the FAAAA does not preempt state-law negligent selection claims against freight brokers. Full stop. Brokers can now be sued in state court for putting an unsafe carrier on the road.

In that context, OOS rates matter not just as a vetting signal but as a documentation question. If a carrier the plaintiff's lawyers are deposing you about had a driver OOS rate of 17%, they will find that number. It's in FMCSA's public data. Their theory will be simple: the broker either didn't look, or looked and didn't care.

If you looked and noted it, asked about it on the T-call, got an explanation, and decided to proceed or not based on what you heard — you have a defensible record. If you looked and said nothing, or didn't look at all, you've given them a narrative. The absence of documentation is how a negligent selection claim becomes a punitive damages conversation.

The diligence itself matters. The documentation of the diligence matters just as much.

How I Document This

Here's what goes in my carrier file when I pull OOS data:

If both rates are clean, the note is short: "Vehicle OOS 11%, driver OOS 3%. Both within acceptable range. No flag."

If either is elevated, the note is longer. That's intentional. More documentation when you're making a judgment call. Less when the carrier comes up clean. The length signals where the professional judgment was applied — and that you applied it.

One more thing: log both numbers even when they're clean, every time. A plaintiff's lawyer who sees you never documented OOS rates will argue you never looked. You want the clean records in there too, because they prove the process was consistent, not something you did selectively when you were worried.

The two numbers take fifteen seconds to note. Those fifteen seconds have a way of mattering later.

— Mason Lavallet

Founder, DOTScreener.com