Mary and Tom talk about lean and 'A tale of two terminals'

A roundup of a talk by Mary Poppendieck

published: 25 May 2011

Thanks to Skillsmatter and the Poppendieck’s for putting on this wonderful free talk up in Farringdon and I look forward to coming to more of these in the future! I feel very lucky to have heard Mary & Tom Poppendieck’s talk this evening.

The talk was based on a blog post/ essay that Mary wrote called “A tale of two terminals” which went viral within a few hours of posting. I won’t repeat the talk as you can read about why the Beijing terminal 3 was such a success and Heathrow terminal 5 struggled so much on or just listen to the whole talk streamed on the Skillsmatter site. (If you skip to 44:00 you can even hear me embarrass myself by asking how to spell “queuing theory”. In my defence I didn’t hear Mary the first time!)

If you ever get the chance to hear Mary and Tom talk, I highly recommend you take the opportunity. They really opened my eyes to what lean is all about as well as some great business insights. It’s these I wanted to share on the blog as well as highlighting a couple of interesting asides Mary did.


Southwest Airlines


Mary talked to us about the story of Southwest Airlines and what made them successful. It all boils down to queuing theory. Southwest airlines run their capacity at closer to 70% instead of the more typical 80%+ of other airlines. Why does less passengers mean more profit for Southwest Airlines? Queuing theory. They know that what makes them money is planes in the air. If you lessen the load a little bit below maximum capacity you can increase the flow through a system.

Just ask anyone who has had to provision the right amount of CPU or RAM for a busy server farm, or dealt with data throughput on a pipe. 100% or anywhere near doesn’t work.

Southwest don’t optimise the size of the plane for each route, instead they only fly one type of plane. That way if a plane is out of action temporarily the next one in can take it’s turn. This maximises flow. This keeps planes in the air.

Southwest allow you to put baggage in the hold for free. This means passengers move on and off the plane more easily. This maximises flow. This keeps planes in the air!

There are always subtle reasons why Queuing theory works, and less than 80% load means the flow is maintained. There are obvious parallels here to lean software development. It’s also a valuable lesson about smart business practices.


Policies or Principles


In company A, how much should we rely on policies and how much do we trust to principles? Mary gave an interesting comparison. Imagine first the army. You command troops organised into small mobile teams. Running around out of reach of central command, having to make decisions on the ground. They naturally have to run with a set of principles they hold to.

Now imagine the Navy. You command an aircraft carrier. Highly technical and if a wrench is left on the flight deck, a plane crash could wipe out half your ship. Naturally you are going to be leaning more heavily on well defined policies.

Now imagine these 2 commanders go out into the real world to lead a company. What companies are they going to successfully run? Probably ones that need a similar style of management. Mary suggested that the Navy commander might be better suited towards running a power station or creating medical devices. Businesses where an awful lot of care and engineering might be required.

Perhaps the Army commander would be better suited towards a software team where small self organising teams thrive. Now we can think about our own businesses and what they really need – policies or principles?


No one wants software


I could go on with more little gems that Mary shared. I will end with this one though. Mary stated that “No one wants software.” They want to accomplish something, and software is always the means to an end. Perhaps not unsurprising to some, but it is an interesting way of thinking to encourage us all to focus on the real goal: Adding value to the business. Making businesses successful. It’s also a great reminder to try and accomplish these goals with the minimum amount of software/systems as possible.

I got so much from Mary’s short talk, these were just some of the highlights. I will definitely be looking around for more of Mary and Tom in the future though.