Mini lecture notes, class 3
•
Course organization
– got group members? (put group number on hwk)
– got the book?
•
•
•
Lego exercise
Reprise Kegworth
How to read a book, 5.2.3 (PQ4R)
– So, preview preface, and preview conclusions soon
•
Chapter 1
– why study the user?
• risk
• better design
• help you be a team member/user
–
–
–
–
•
ABCS
not covered: emotions, esthetics
when?
How much do you have to study the user?
Chapter 2
– CHI, HCI, HF, cog. Ergonomics, systems, user-centered design
•
Course project reminder
What causes a plane to crash?
• A laundry list is required, or, a swiss cheese
loaf lined up
• A lot, in safety critical systems
Kegworth Air Disaster
• Why?
– Near Ritter,
Baxter &
Churchill
– A lovely example
– Often used
Storyline
• Flight, jan 1989, Heathrow to Belfast, Midland 192
• Experienced pilots, new plane (737)
• Part of one of the safest systems in the world
• Upon take-off, no problems
• Shuddering, fire in an engine at ~10 min.
• Shut off #2 engine, RHS (the good one!)
• This is the pilot error
Hardware and Mischance
badly designed new engine, failure at 3 months, approx.
t=300 h, should be t=500,000 h, not tested at altitude
/unlucky choice of diversion airport
[BMI hub]
Auto throttle problem
poor mental model of plane [system]
(turned off good engine, which disengaged
autothrottle, solving the judder problem)
lack of engine feedback
[interface design]
Vibration Dial 1
vibration dial harder to read [design]
vibration dial not required to fly [regulation]
dial and plane not trained with simulator
technology updated but not announced
Vibration Dial 2
• vibration dial
small [design]
• Without range
marking
[design]
During descent
lots of interruptions
pilots can’t see the engines
no protocol: no checking/confirmation
visually from cabin
• Passengers could see fire but explained it
away, perhaps also flight attendants
diffusion of social responsibilities
Social distance between aircrew and pilots
crash
• 900 m short
• 43+4 out of 118+8 die
+1 in 2012 (PTSD)
At crash
• Not documented: noise abatement hillocks
Afterwards
• If any 13or 3 missing, no loss of life
• What was the pilot error?
• Thus, systems require understanding
people, technology, and systems and
environment
References
• Wikipedia on kegworth
• BBC. (1991). Fatal error: Taking liberties
[television series].
• Youtube has videos as well
1.3 So, when to study the user?
•
•
•
•
•
Fundamental attribution error of design
More usable
$$
Safer
Risk driven
– Not like you
– Lives at risk
– Know enough given cost of knowing more
(satisficing)
The ABCS
• Anthropometrics
• Behavioral
– The senses
– Motivation
• Cognition
• Social
• System
• The system
(pre-HCI)
• The system and user
(early HCI)
• The system and what
we know about the
user
(U-CS)
Another way to organize the user
• The system
(pre-HCI)
• The system and user
(early HCI)
• The system and what
we know about the
user
(U-CS)
Chapter 2
QuickTime™ and a
decompressor
are needed to see this picture.