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.

What the investigation does establish is that the mate's duty pattern in the period preceding the incident was consistent with accumulated sleep debt. Inland waterway towing operations often involve watch schedules that don't align with circadian rhythms, and vessels operating in port-to-port turnaround cycles don't always offer the recovery time that longer ocean passages do.

What Watch Officers Should Take From This

The practical lessons from the Mackenzie Rose investigation apply well beyond towboat operations:

• Steering mode transitions require active attention, not passive switching. The moment of changeover is a moment of increased vulnerability — both because vessel behaviour changes and because cognitive load briefly spikes.
• Fatigue and routine are a dangerous combination. Familiar waterways breed familiarity, and familiarity reduces the mental alertness that dangerous waterways demand. The Elizabeth River is not an unfamiliar transit — which is exactly why the mate's attention may have been elsewhere.
• Voyage data recorders are not the enemy of a fair investigation. The NTSB's ability to reconstruct this incident relied on recorded data. Understanding your vessel's voyage data systems and what they capture is part of modern professional competence.

The NTSB's full report on the Mackenzie Rose is publicly available. For any seafarer involved in towing operations, inland waterways, or constrained channel transits — it's worth an hour of your time.