What an Out-of-Service Rate Says About a Carrier

An out-of-service (OOS) order is issued during a roadside inspection when an inspector finds a violation serious enough that the driver or vehicle can't legally continue until it's fixed — a driver operating past hours-of-service limits, for instance, or a vehicle with brakes that don't meet minimum standards. An out-of-service rate is simply the share of a carrier's inspections that resulted in one of these orders, and it's one of the more direct safety signals available, because it reflects an inspector's real-time judgment rather than a paperwork review.

Driver OOS rate vs. vehicle OOS rate

These are tracked separately because they point to different kinds of problems. A driver out-of-service order usually relates to hours-of-service violations, missing or invalid credentials, or impairment — issues with the person behind the wheel. A vehicle out-of-service order relates to the equipment itself — brakes, tires, lighting, steering, and other mechanical defects found during inspection. A carrier can have very different rates in each category; a fleet with well-maintained trucks but a habit of pushing drivers past their hours will show that imbalance clearly if you look at both rates rather than a single combined number.

How the rate is calculated

At its simplest, an out-of-service rate is the number of inspections that resulted in an OOS order divided by the total number of inspections, expressed as a percentage. CarrierPedia calculates this over a rolling 24-month window, since older inspection results become less representative of a carrier's current operation, especially for a fleet that's grown, shrunk, or changed its safety practices since then.

Why the raw rate alone can mislead

A carrier with one inspection and one out-of-service order has a 100% rate — technically accurate, but not statistically meaningful. A single data point can't distinguish a genuinely unsafe operation from bad luck on one inspection. That's why sample size matters: a rate calculated from thirty inspections tells you much more than the same rate calculated from two. Whenever you look at an OOS rate, check the underlying inspection count alongside it.

What counts as high or low

Rather than relying on a fixed rule of thumb, the more reliable approach is comparing a carrier's rate to the national median among carriers with a similar level of inspection activity — carriers with too few inspections to be statistically meaningful are excluded from that comparison. CarrierPedia calculates this median directly from its own database of active carriers and shows it alongside each carrier's own rate, so "27% vehicle out-of-service" comes with the context of what's typical, rather than being left to interpretation. Rates well above that median, especially paired with a meaningful number of inspections, are a stronger signal than the raw percentage alone.

How OOS rates relate to BASIC scores

Out-of-service results feed directly into two of FMCSA's five BASIC categories — Vehicle Maintenance for equipment-related orders, and a mix of Driver Fitness, Hours-of-Service, and Unsafe Driving depending on the specific driver violation. See What the Five FMCSA BASICs Actually Measure for how these categories are built, and Reading an Inspection Report: Levels 1–6 for what an inspection actually checks depending on its level.

Using this as part of a broader check

An out-of-service rate is one piece of a carrier's safety picture, not the whole thing — it's worth reading alongside crash history, whether operating authority and insurance are current, and how long the carrier has been in operation. See How to Verify a Carrier Before Booking a Load for how these pieces fit together, or look up a specific carrier directly with DOT Number Lookup.