Sunday, October 30, 2011

Spec review: Airbags?

One of the many skills a Project Manager needs, is the ability to review functional specifications.


A Project Manager needs to be able to run a spec-review meeting and follow up the action items and document the changes resulting from the meeting.


Another required skill is the ability to persuade people that everything needs a spec and a review.


Why is that? Let's take a non-programming example, for a change; since I've been getting complaints that my blog is very programming oriented.


In 1971 GM added airbags to the driver's side. Since the airbag worked well for the driver, why not install it on the passenger's side also. Source: Wikipedia: Airbags.


Sounds simple enough: Here's what the MRD (Marketing Requirement Document) may have said: "Take existing design of airbag and add it to the passenger side."


Hardly needs a design, functional spec and review, does it? Seems that implementing it will be trivial; what could possibly go wrong?


If anything, it's way more complicated to add it to the driver's side, since the steering wheel is in the way.


Fortunately they did a spec review, and here's some of the issues that were revealed:


  • What happens of an infant is in the passenger seat? Won't the airbag serous injure / kill it?
    • Solution: Put a weight sensor. Do not deploy if weight less that 3 year old child. 
    • Action item: Find out minimum weight from medical dept.
    • Action item: Inform legal that a new "anti-infant" clause needs to be added to standard car contract.
  • What happens if the infant is in a car seat? it will be heavy enough to be detected as an adult... yet the result could be fatal...
    • Add switch to manually override the airbag.
      • Where should we place this switch? passenger side? drivers' side? in between?
        • Since it's to protect infants, needs to be on driver's side.
        • Needs to be far enough away from passenger that kids don't play with it during travel.
      • Does it reset when ignition is turned off, or does it remember its state?
        • Could be fatal if it resets; better if it remembers state.
      • Add a warning beep to sound when airbag is turned off.
      • Add a warning beep if passenger is too light and airbag is turned on.
      • How can we prevent it being turned off accidentally?
        • Maybe it should require car-key to flip on/off.
        • Decisions: try both options and track customer feedback.
    • Add light to dashboard to indicate that airbag on passenger side is deactivated.
    • Action item: Design relevant icon - graphics dept.
  • How will drivers know when to turn the airbag off, and what all the icons and beeping mean?
    • Action item: Get stickers made to explain the infant-hazard; get wording from legal, design from graphics dept.
  • Should airbag always deploy?
    • Maybe it should only deploy if the seat-belt is buckled? This way it won't unnecessarily if only groceries are in the passenger seat.
    • On the other hand, the airbag is most useful when the passenger is not wearing their seat-belt.
      • Decision: Deploy independently of seat-belt being buckled.
As we can see, this trivial, easy to implement feature has become a project involving the following departments: legal, graphics and medical.

It requires a redesign of the buttons sections and the icon on the dashboard. It also requires a new type of switch that gets turned by the key.

We now know why the first passenger-side airbags didn't appear until 1973.

Finally, we also have plenty information in order to create a full-length functional specification, which everybody will understand why it's needed, and many people from various departments will be required to review.  

So now we know!

- Danny Schoemann

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