One Switch, One Bridge Strike: What the NTSB Found on the Mackenzie Rose

The Elizabeth River, Virginia. 15 June 2024. A towboat pushing a loaded barge is transiting toward Chesapeake. The mate is on watch. At some point — the investigation establishes the moment but not the exact reasoning — they switch from autopilot to hand steering. What happens next results in the bow of the barge striking the Norfolk and Portsmouth Belt Line Railroad Bridge, causing significant structural damage. No injuries. No pollution. A complete investigation.

The US National Transportation Safety Board released its findings in May 2026, nearly two years after the incident. The report is worth reading in full, but its core findings are concise enough to understand in minutes — and relevant to anyone who has ever made the same transition the mate made that morning.

The Autopilot-to-Hand-Steering Transition

The NTSB concluded that the mate likely lost control of the tow after switching between autopilot and hand steering. The word "likely" matters here — the investigation reconstructed events from voyage data, bridge recordings, and witness accounts. No single catastrophic failure caused this. What caused it was the interaction between a steering mode change, a vessel already in motion, and — the NTSB's second finding — probable fatigue.

The autopilot-to-hand-steering transition on a tow is not trivial. A towboat pushing a loaded barge has significant momentum and a very different handling characteristic to a vessel operating without a tow. Autopilot systems on inland towing vessels are typically set to manage heading corrections in small increments. Hand steering transfers that workload entirely to the helmsman — who must now actively compensate for current, wind, and the tow's own tendency to push the stern in one direction or another.

Done under optimal conditions, by a rested and experienced officer, this transition is routine. Done at a moment of fatigue — as the NTSB suggests was likely the case — the window between "under control" and "committed to a heading that ends at a bridge structure" can be very short.

Fatigue as a Contributing Factor

The NTSB's fatigue finding is carefully worded. The investigation does not conclude that the mate was impaired or that fatigue was the sole cause. It concludes that fatigue was probably a contributing factor — which in NTSB language means the evidence supports it as a plausible contributor without being able to definitively confirm it.