What 393.78-WOOS means in plain language
A 393.78-WOOS citation means an inspector found your windshield condition impairs your ability to see the road clearly. This isn't about minor nicks or small chips in the corner—it's about anything that materially blocks your line of sight or makes safe operation harder.
Examples include large cracks spreading across the glass, heavy crazing or pitting that distorts vision, a detached laminate layer, missing sections of glass, or severe dirt or obstruction you haven't cleaned. The standard is practical: if the windshield prevents you from seeing where you're going or what's coming, it's a violation.
You must be able to see the road and traffic clearly from your normal driving position. This is a foundational safety rule—windshield visibility directly affects your reaction time and ability to navigate safely in all conditions.
What our enforcement data actually shows
Across our inspection database of 13 million+ records, 393.78-WOOS ranks #880 by citation volume among all 3,036 FMCSR codes. Over the past 12 months, we recorded 284 citations nationwide. In the last 90 days, that figure was 53 citations.
A critical distinction: while this violation is cited, it is not OOS-eligible. That means inspectors cannot remove your truck from service solely because of a defective windshield. However, our all-time data shows that 258 of the 562 total citations resulted in out-of-service status—a 45.9% OOS rate. This occurs when the windshield defect is paired with other violations that are OOS-eligible, or when the condition is so severe that the truck is deemed unsafe to operate. For context, the all-FMCSR average OOS rate is 31.4%, so this code's actual OOS rate runs about 14.5 percentage points higher.
The monthly trend over the past year shows spikes in May (34 citations, 17 OOS), August (35 citations, 17 OOS), and December (33 citations, 17 OOS), suggesting seasonal patterns—possibly winter weather damage and spring/early summer inspections uncovering accumulated damage.
Who gets cited most
Over the past 180 days, New Jersey leads enforcement with 26 citations and a 15.4% OOS rate. California follows with 14 citations but a much higher 42.9% OOS rate, indicating more severe conditions at citation. Pennsylvania reported 10 citations with a 50.0% OOS rate, suggesting frequent pairing with other violations.
Notably, states like New York, Washington, Ohio, and Arizona each recorded 6–8 citations with 100% OOS rates in this period—small numbers, but when cited, the windshield defect almost always coincided with other enforceable violations that triggered out-of-service status.
Our records show carriers such as Brooks Transportation Inc, Los Angeles Unified School District, and Federal Express Corporation with 3 citations each in our all-time database. This reflects broad exposure across fleet types and business models rather than systemic operator negligence.
How severe is this compared to similar codes
Within the Vehicle Maintenance category, windshield violations sit in the middle of enforcement intensity. The peer code 393.9 (Inoperable required lamps) has generated 660,737 citations—vastly more frequent. Another peer, 396.3(a)(1) (Inspection/repair/maintenance general), has 236,919 citations and a 45.3% OOS rate, almost identical to 393.78-WOOS's 45.9% rate.
Compare also 393.78 (the broader windshield condition code across all inspection types), which has accumulated 157,894 citations all-time but only a 0.3% OOS rate—suggesting that when windshield issues are detected in routine inspections, they're usually correctable minor issues, whereas the 393.78-WOOS specific violation (typically flagged at roadside) tends to be more severe and more likely to trigger other violations.
How to avoid it
Prevention starts before you roll out each morning.
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Do a thorough pre-trip windshield walk-around. Look at the entire glass surface—front, sides, corners—from multiple angles in daylight. Check for cracks, crazing, laminate separation, or loose glass. If you see anything that might impair sight lines, replace or repair the windshield before departure.
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Clean your windshield and windows completely. Road grime, bug splatter, salt spray, or mud reduce your effective vision. Carry cleaning supplies and use them daily. Dirty glass can be flagged if it materially impairs your view.
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Inspect wipers and washer fluid. Defective wipers worsen visibility in rain or snow. Verify your washers work and fluid is full. These aren't directly 393.78-WOOS violations, but our data shows 392.2 (Operating a CMV while ill or fatigued) co-occurs 11 times in the past 90 days—fatigued drivers are more likely to miss windshield defects and operate in poor visibility.
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Monitor your vehicle's age and history. Our top cited vehicle makes include Freightliners, International trucks, Peterbilts, and Kenworths. These are common workhorses, but older units or high-mileage trucks are more prone to glass failure from road vibration and temperature cycling. If your truck has significant mileage, windshield inspection should be more frequent.
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Check inspection and maintenance records. Our data shows 396.17C-PI (No proof of periodic inspection) co-occurs 14 times with windshield defects in the past 90 days. Keep documentation of any windshield service or replacement. A repair receipt proves due diligence and may support your defense if the citation is challenged.
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Address windshield damage immediately when discovered. Small cracks grow fast under road vibration and temperature stress. A $200 repair now beats a citation and potential out-of-service placement later.
Your windshield is safety equipment, not cosmetic. Treat defects as urgent maintenance, not something to postpone.