Procedural drift and the sandbar

On 3 January 2015, the large ship MV Hoegh Osaka left the British port of Southhampton. An hour later she made a turn to port, then began listing markedly to one side. Soon enough the rudder and propellor were out the water. In flying terms, ‘departure from controlled float’ we could say. Fifteen minutes after the turn she was grounded on the Bramble Bank sandbar off the Isle of Wight. Settling down with a list that would eventually reach 52°. The ship was about half full, loaded with 1,200 Jaguar and Land Rover vehicles worth over $45 million.


Now, this accident isn’t as serious as the Titanic (which also left from Southhampton), as here everybody lived. But this was just last year. A Japanese-built modern ship. Auto-everything. Good weather, certainly no icebergs. Ship under the control of a Southampton pilot. Leaving a busy international port that has over two thousand years of continuious use, a traditional hub of British sea power and commerce.

The pilot wasn’t drunk. There was no terrorist plot. No failure of machine or computer. No rogue wave. So how did this happen?

The respected British Marine Accident Investigation Branch (MAIB) released their report this month. Their key finding is:

“No departure stability calculation had been carried out on completion of cargo operations and before Hoegh Osaka sailed. Witness and anecdotal evidence suggests that this practice extends to the car carrier sector in general. The fundamental requirements for establishing before departure that a ship has a suitable margin of stability for the intended voyage had been eroded on board Hoegh Osaka such that unsafe practices had become the norm.”

In flying terms, the weight and balance calculations were not done. (Mass and balance is the more correct term, I was a physics major, but I digress.) The ship was not stable in a tight turn. It turned, and listed, and could not recover. If it ‘departed controlled flight’ we might say.

This was not a one-time slip or error or mistake. This was apparently common industry practice. It was so common that unsafe practices had become the norm.

Hoegh Osaka

We call this procedural drift; it’s the unintended, systematic adaptation of routine practice from written procedure. We saw it in the Space Shuttle Challenger accident, the friendly fire shoot-down of two US Black Hawk helicopters, the Deepwater Horizon drilling rig, and many other events. In The Field Guide to Understanding Human Error Prof. Sidney Dekker lists several potential reasons for procedural drift:

  • Rules or procedures are over-designed and do not match up with the way work is really done.
  • There are conflicting priorities which make it confusing about which procedure is most important.
  • Past success (in deviating from the norm) is taken as a guarantee for safety. It becomes self-reinforcing.
  • Departures from the routine become routine. Violations become compliant behavior with local norms.

Over time we deviate a little from written standard operating procedures, and nothing bad happens. Until it does.

“Witness and anecdotal evidence suggests that the practice of not calculating the actual stability condition on completion of cargo operations but before the ship sails extends to the PCC/PCTC sector in general. For reasons of efficiency, what is a fundamental principle of seamanship appears to have been allowed to drift, giving rise to potential unsafe practices.”

We’ve all seen it. We’ve all done it. But we are repeatedly amazed when an incident happens. This week Lloyds List Intelligence said about the accident:

“Two things are infinite: the universe and human error.”

I’m not sure about the physics of the first part, but it does make for a good headline! The potential danger of these kind of errors should be well-known as stability incidents have happened before on sea-going car carriers, such as the Cougar AceTricolor and Baltic Ace. Lloyds continued to say:

“The report found shortcomings in training, procedure and crew attitude that suggest the myriad contributory factors to this casualty have occurred individually on many other sailings.”

“Rather than a freak occurrence from a catastrophic failure, the incident looks to be a statistical inevitability. When small risks are occasionally or routinely accepted in multiple areas, there will eventually come a time when those risks all conspire to become something much more significant.”

The sands of time ran out for the MV Hoegh Osaka on the Bramble Bank sandbar. So, is the clock ticking on your weight and balance calculations? Do you ever takeoff ‘just 10 pounds’ overweight? Or skip some takeoff performance because you’ve safely done it just like this a hundred times before?

Is it time to check the drift?

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