FMCSR 393.78A-WS: Defective Windshield – Driver Q&A

No — virtually never. Across 69,791 all-time citations in our inspection records, only 9 vehicles were placed out of service under 393.78A-WS, producing an effective OOS rate of 0.0%. Compare that to the all-FMCSR average OOS rate of 31.4% and it's clear inspectors rarely pull a truck for this violation alone. You'll almost certainly be allowed to drive away, but the citation still goes on your record and feeds your CSA score, so don't treat it as harmless.

4 severity points are assigned to 393.78A-WS under the CSA scoring system. Those 4 points are then multiplied based on how recently the inspection occurred — violations in the last 6 months carry the heaviest weight, with a time multiplier applied on a rolling basis (inspections within 6 months are multiplied by 3, 6–12 months by 2, beyond 12 months by 1). Because our records show 43,716 citations in the last 12 months alone, enforcement is active and fresh violations are hitting carrier scores hard. The citation stays in the CSA window for 3 years.

Act on it the same day. Here's a practical sequence:

1. Document the windshield condition with photos before any repair — you'll need this if you contest the citation.
2. Schedule windshield repair or replacement immediately. The violation signals an impaired field of view; that's a safety issue regardless of OOS status.
3. Check your full inspection report for co-occurring violations. Our inspection data shows that in the last 90 days, 393.78A-WS appeared alongside 396.17C-PI (no periodic inspection proof) in 1,717 shared inspections and 393.9A-LIL (inoperable lamps) in 1,269 shared inspections — those carry their own CSA hits.
4. Notify your fleet manager so the repair is logged in your maintenance records before your next inspection.

Less severe than most peers on OOS risk, but still a high-volume code. Our inspection records rank 393.78A-WS #37 out of 3,036 FMCSR codes by citation volume — that's top 2% nationwide. Within its peer category, codes like 396.3(a)(1) carry a 45.3% OOS rate and 393.9(a) carries a 15.4% OOS rate, while 393.78A-WS sits at 0.0%. So it won't park your truck, but with 43,716 citations recorded in just the last 12 months, inspectors are actively looking for it. A 4-point CSA severity weight also means repeated citations can meaningfully degrade a carrier's Vehicle Maintenance BASIC score.

Yes, you can file a DataQs Request for Data Review (RDR), and an equipment-condition citation like 393.78A-WS can sometimes be successfully challenged. Strong grounds include: the inspector's description of the defect doesn't match the vehicle's actual condition (supported by your photos), the citation was entered with incorrect vehicle or carrier information, or the windshield was repaired and re-inspected before the record was finalized. Because this is an observed equipment finding rather than a missing document, you'll need physical evidence — photos, repair invoices, or a clearance inspection — to support the challenge. File through the FMCSA DataQs portal and track the RDR status; the reviewing state agency typically responds within 60 days.

Arizona, Florida, and Alabama are the three busiest enforcement states for this violation in our database. Over the last 180 days, Arizona logged 2,271 citations, Florida recorded 1,466, and Alabama came in at 1,420. The national total for that same period was 2,547 citations coded to a general US jurisdiction, with New York (1,127), Maryland (655), and Washington (637) rounding out the top tier. All of these states show a 0.0% OOS rate for this code, consistent with the national pattern — citations are issued but trucks are not parked.

Urgently — don't wait for your next scheduled PM. Our inspection records show 393.78A-WS citations are accelerating: the code generated 7,743 citations in just the last 90 days and peaked at 4,592 citations in a single month (July 2025). Enforcement is clearly elevated, meaning the odds of a follow-up inspection catching an unrepaired windshield are real. While the OOS rate is 0.0% historically, a second citation compounds your CSA score with another 4 severity points. Repair the windshield, retain the invoice, and update your driver vehicle inspection report (DVIR) to document the corrective action.

Both are affected, but in different ways. In the FMCSA CSA system, vehicle maintenance violations like 393.78A-WS are attributed to the carrier's Vehicle Maintenance BASIC score, since the carrier is responsible for keeping the equipment in safe operating condition. The driver's record is also associated with the inspection event, which can be visible to carriers during pre-employment screening through the Pre-Employment Screening Program (PSP). Our records show FEDERAL EXPRESS CORPORATION (USDOT 86876) leads all carriers with 147 all-time citations under this code, illustrating how repeated equipment violations accumulate against a carrier's safety profile regardless of which driver was behind the wheel.