Challenger disaster AcciMap

5 Whys of the Challenger disaster

Event: Astronauts couldn’t escape from disabled Space Shuttle during launch.

1.       There no Egress system on the shuttle:

2.       Weight / payload thrust limits

3.       Cost of per launch would increase by either smaller payload or bigger rockets

4.       Limited budget, NASA financial pressures

5.       US Government funding

 AcciMap

1 –Event
Astronauts couldn’t escape from disabled Space Shuttle during launch.
2-Organisation
Weight limits for the Shuttle design
3-Company
Cost per kilogram of payload to launch into space.
4-Government
Limited government budget for NASA
5-Societal
Public perception of NASA safety record

Shark Attack

Image from Google Images

On Saturday 31March a fatal shark attack in a diver in Western Australia occurred. The divers’ brother was diving with the deceased diver and recovered what was left of his brother. I couldn’t imagine what it would be like to see your brother killed by a shark and then have the unenviable duty of recovering his body and transporting him back to shore.

After authorities learned of the attack they went looking for the man killer shark. No order was given to kill the shark but the potential was to give the order. The question is why do sharks attack humans?

There is a perception that humans in dive wetsuits would look like seals to sharks under water. Seals are a favoured food source to the Great White shark, so if we looked like a seal then we would also be on the menu.
If we look like seals than why don’t we change the colour of the wetsuits? As light descends into water, the band widths of visible light are absorbed by the water starting with the reds at approximately 10m. At greater depths than ten meters, red disappears and whites appear blue, so changing the colour of wetsuits would not have any effect underwater.

Shark eyesight is said to be very good, indeed they are reported to be able to see extremely well particularly in reduced light. If their eyesight is good then why can’t they distinguish the difference between humans and seals?

Shark tourism could be a factor of shark attack. Cage diving to view Great White sharks is designed to attract sharks. Burly is poured into the water and then the sharks are further attracted by bait. Sharks may be associating divers with a food source due to this practice.
Image from Google Images
This time of year there are more bait fish schools closer to shore, which attract larger predator fish and they are then a food source for sharks. Early morning and late afternoon are predominately feeding times for sharks.

I believe that a possible solution to preventing shark attack on humans is for humans to understand a shark’s environment and behaviours. First we need to stop attracting sharks with food and cage diving. Educate people about the habitat of sharks and the behaviours such as feeding times and food source migrations.

Humans aren’t the sharks primary food source, if we were there would be many more people being taken.

References:

ReefQuest centre for shark research, 2007, Vision and a Carpet of Light, Biology of Sharks and Rays. Viewed 31/03/2012.

http://www.elasmo-research.org/education/white_shark/vision.htm