© 2010 David Gustafsson

Blue Mountains is on fire

Today the sky in Sydney has been red, or at least the sun. This happened for about 4 months ago when there was a sandstorm in the outback. This time the rumour says that there has been a fire in Blue Mountains. Whenever you go out you can feel the smell of fire. I went for a run but aborted half way through due to the smell and a sticky feeling in my sensitive throat.


The following can be read from NSW Rural Fire Service web page:

Smoke in the Blue Mountains

Posted: 11/05/2010
National Parks and Wildlife Service are conducting a hazard reduction in the Massif Ridge (Blue Labyrinth) area of the Blue Mountains. NSW Rural Fire Service is providing assistance.

It seams like the fire/smoke is only due to a controlled exercise for reducing the fire risk. There is therefore nothing to worry about and hopefully the sun will be visible in Sydney tomorrow again! Currently the fire danger in the area is between very high and severe which has started the hazard reduction.

Recently I made an assignment in the course Management of Risk on the topic “hazard reduction for fire”. The task involved looking at the best measure to decrease the probability of the whole forest burning down. A utility curve as constructed for different percentages of forest burning down. In the end it actually turned out that burning 5% of the forest to decrease the probability of the rest of the forest burning down was the best option. This is exactly what I think is done at the moment so the numbers where actually somewhat related to reality.

Another example that management of risk professors love to discuss is related to redundancy. A reason for having more than one engine on an air-plane is that if one fails there is still enough power in the other engines to land the plane. In some cases this way of thinking is OK if the assumption is made that the engines fail independent of each other. However this is not always the case.

In 1982, all four engines on a British Airways Plc Boeing Co. 747 flying to Perth, Australia, shut down as the aircraft encountered ash spewed from Mt. Galunggung in Indonesia. The plane fell for almost four miles before the pilot was able to restart three engines and make an emergency landing in Jakarta. (Business week, 2010-04-15).

The ash was a common failure mode causing all the engines to die. You should always be aware of common failure modes when you try to use redundancy to increase the reliability of your system…

On volcanic ash:

Why cant planes fly through volcanic ash?