On November 7, 2007, the Hong Kong-registered, 901-foot-long containership M/V Cosco Busan allided with the fendering system at the base of the Delta tower of the San Francisco–Oakland Bay Bridge. Contact with the bridge tower created a 212-foot-long by 10-foot-high by 8-foot-deep gash in the forward port side of the ship and breached the Nos. 3 and 4 port fuel tanks and the No. 2 port ballast tank. As a result of the breached fuel tanks, about 53,500 gallons of fuel oil were released into San Francisco Bay.
1 | Incident snapshot
| Impact time (LT) | 08:30 |
| Visibility | < 0.25 nm (heavy fog) |
| Speed on impact | ≈ 10 kn |
| Key human factor | Pilot mis-identified two lateral buoys as mid-span and remained on a diverging heading |
| Cognitive backdrop | NTSB found the pilot’s performance was degraded by multiple prescription drugs (modafinil, lorazepam, hydrocodone, sertraline, …) that can diminish alertness and judgment |
| Consequences | 212 ft × 32 ft hull gash, ≈ 53 000 gal HFO spill, > USD 70 m direct cost |
2 | Human-factor timeline
| Time | Bridge dialogue / action | Issue surfacing |
|---|---|---|
| 08:22 | Pilot: “This is the centre of the bridge, right?” – Master: “Yes.” | First sign of loss of awareness |
| 08:25 | Orders full-ahead + starboard 20° while track already diverging | Growing confusion |
| 08:27 | VTS: “COG 235°.” – Pilot: “I’m steering 280°” (actual 262°) | Confusion confirmed |
| Helm commands flip hard-STBD → mid → STBD 20 → hard-STBD; voice pitch climbs | Erratic decisions | |
| 08:30 | Port bow strikes bridge fender | — |
The pilot’s reduced cognitive margin—linked to his medication regimen—meant these escalating cues went unrecognized in real time.
3 | Alternate sequence with HOM active
| Time | HOM cue | Likely crew action | Outcome |
|---|---|---|---|
| 08:22:05 | Clear on‑screen mismatch advisory appears | Master re-checks alignment; pilot realises buoys ≠ centreline | Course corrected early |
| 08:27:45 | Clear on‑screen mismatch advisory appears; short attention tone | Master slows to half-ahead, takes con, orders port 10° | Track re-aligned mid-span |
| 08:29:30 | Banner clears as awareness score recovers | — | Vessel passes safely beneath span |
| 08:30 | (Impact in reality) | — | Allision averted |
4 | Benefit at a glance
- Several minutes of intervention window between first advisory and would‑be impact.
- Slowing to 8 kn and correcting heading restores > 60 m clearance.
- Avoids > USD 70 m damage, oil-spill clean-up, legal penalties.
5 | Why two simple cues are enough
- Progressive prompting — cues escalate as needed; delivery minimises distraction.
- Plain language — advisory only; never forces acknowledgements or takes control.
- Bridge remains in command — cues support bridge resource management.
- Logged to voyage data — preserves when steering input or feedback ceased.
Take-home message
The close‑quarters transit was already demanding; a concise mismatch advisory would have surfaced the problem, buying the bridge team precious minutes to slow down, verify, and steer clear.
