Maximum Tolerable Outage by Whose Criteria?

Maximum tolerable outage means what it says – the longest time that an organisation can accept that a given service or facility is out of operation. Many enterprises and institutions go to great lengths to predict and calculate MTO, usually because of what’s at stake. Hospitals for example cannot accept IT outages that disrupt critical patient monitoring systems, and stockbrokers can perhaps only tolerate outages of a few minutes. However, and as astonishing as that may seem, some entities involving groups of thousands of people don’t appear to take MTO into account when hit by natural disasters.

Snow can be one of those disasters, when it falls heavily and suddenly enough to block roads and trains. In major cities in countries where this meteorological phenomenon occurs, heavy snow can deny employees access to their place of work, leading to losses sometimes calculated in billions of dollars. More frustrating still is the game of trying to forecast where snow is most likely to fall, so as to have the necessary equipment on hand to clear it as fast as possible. In the UK some years ago, snow ploughs for clearing rail tracks had been mostly located in the north (a logical choice), when freak weather conditions led to heavy precipitation and overruns of maximum tolerable outages in the unprotected south.

By comparison, some towns in Mediterranean countries can reasonably expect that snow will be very rare and typically light if it ever does fall. However, in 2009, there was unexpectedly heavy snow in areas of the south of France, a region known for its sunny and relatively warm weather. The snow fall was enough to render the roads unusable for most people overnight. At least one municipality simply shut down schools in the locality, and most shop-owners did the same. While sanding and salting did go on, the general policy was simply to wait till the snow cleared. Business continuity? Maximum tolerable outage? Not everyone has the same point of view.