The Titanic: a simple example

Transcription

1 : a simple example Why did the sink? 1 1

2 : a simple example Why did the bulkheads fill with water? 2 Don t skip the obvious ; if it s a incontrovertible fact, document it; if it s an assumption, test to disprove. 2

3 : a simple example Why did the bulkheads fill with water? 3 An enabling cause the smaller bulkheads filled with water faster than larger bulkheads 3

4 : a simple example How did water enter? 4 4

5 : a simple example Puncture of steel plates 4 possible ways for water to enter Ripping or tearing of steel plates Swamped 5 In order to answer this question, we need specific scientific proof. 5

6 causal system of the sinking of the Why did the seams? 6 Again this question requires specific scientific proof 6

7 causal system of the sinking of the Why did the rivets shear? 7 s found in the debris field were found in great numbers to have been sheared at the rivet head. forces are very easy to identify under metallurgical examination. Eye witness ear witness accounts reported hearing popping noises like ball bearings or marbles hitting the floor at eth time of the impact. 7

8 causal system of the sinking of the Why did the rivets shear? 8 Metallurgical examination revealed the presence of extensive slag in the rivets which is known to weaken the strength of metal. But the rivets didn t shear on their own 8

9 causal system of the sinking of the Condition for Failure Side Swipes Iceberg; shear forceapplied along side of ship Physical Root Cause 9 4 Whys (2 asked twice) to get to causal mechanism. This is the classic strength-stress interaction. We could go further and indentify why slag was in the rivets although this was a scientific/manufacturing constraint at the time. But at this point we have enough specific information about the causal mechanism to develop a viable solution. seams need to be held together by a stronger fastening system. In this case actions to guard against the condition for failure are futile. Any sideswipe can cause the rivets to shear; in fact this is how the Olympia failed.. 9

10 causal system of the sinking of the Why did the titanic hit the iceberg? Side Swipes Iceberg; shear forceapplied along side of ship 10 This is the classic strength-stress interaction. We could go further and indentify why slag was in the rivets although this was a scientific/manufacturing constraint at the time. But at this point we have enough specific information about the causal mechanism to develop a viable solution. seams need to be held together by a stronger fastening system. In this case actions to guard against the condition for failure are futile. Any sideswipe can cause the rivets to shear; in fact this is how the Olympia failed.. 10

11 causal system of the sinking of the Systemic Causes Lookouts See Iceberg too late; swerve to avoid Side Swipes Iceberg; shear forceapplied along side of ship 11 11

12 causal system of the sinking of the Systemic Causes Dark & overcast conditions reduce visibility Lookouts See Iceberg too late; swerve to avoid Side Swipes Iceberg; shear forceapplied along side of ship 12 12

13 causal system of the sinking of the Systemic Causes Dark & overcast conditions reduce visibility Lookouts See Iceberg too late; swerve to avoid Side Swipes Iceberg; shear forceapplied along side of ship sailing too fast for conditions 13 13

14 causal system of the sinking of the Systemic Causes Dark & overcast conditions reduce visibility Lookouts See Iceberg too late; swerve to avoid Side Swipes Iceberg; shear forceapplied along side of ship sailing too fast for conditions Captain ignores iceberg warnings 14 14

15 causal system of the sinking of the Systemic Causes Dark & overcast conditions reduce visibility Lookouts See Iceberg too late; swerve to avoid Side Swipes Iceberg; shear forceapplied along side of ship sailing too fast for conditions Captain ignores iceberg warnings White Star pushes for record crossing time 15 This is a relatively simple example that really didn t require sophisticated experimental structures to answer any of the 5 Why questions. It does show the basic flow of causal mechanism and the separation of systemic, enabling and physical causes. 15