What do you mean by “to remove that comment”?
The difference between the two sentences I see is the remark about “hierarchically structured”. I don’t know where this difference comes from – it was not a conscious decision and most likely it just happened in the writing process, i.e., there’s no deeper meaning behind it 🙂

What inspired you to create flight levels? I would like to know what the advantages are and if you have a case using flight level, Thanks

Klaus, while I was reading your blog post the SAFe layers (Team, Program, Portfolio) came to my mind. What would you say about the differences between the three flight levels and these three SAFe layers? Thanks!

Unfortunately this link take you to a “403 – forbidden” page.
Winston Royce described the waterfall model as an iterative process

Hi, Steve, thanks for bringing this to my attention. Probably the providers have blocked the link :-/

I really like this, it aligns very well with how I learned to run projects when I first started working in IT. However, in my experience of waterfall we never, ever pulled a whole project in one go. Always phased, maximum quarterly, with reviews and chances to change direction. Not so different from PSIs, for those who’ve worked with SAfE. And actually cross-functional interaction was often much better than now with Scrum (including actual users in my definition of cross-functional). I think younger developers often forget how much we were constrained by hardware and software limitations (talking about the 80s and 90s here). Overnight compilation before you can see if your code has worked and every last bit (yes, bit) being made to do 3 things means you have to get it right first time and you’d better focus first on good design.

Hi Klaus, someone just pointed me to this and although its an old post I could not resist commenting. The idea of different levels is something well explored by Elliott Jaques (Requisite Organization) and Gillian Stamp (BIOSS) (http://www.bioss.com/approach/matrix-of-working-relationships) and of course Staffford Beer’s work on the Viable System Model explains in detail the key systems required for a viable organisation. There is also the most excellent work by Luc Heobeke which brings all three together (http://www.simenvandergoot.nl/media/makingworksystemsbetter.pdf)
I guess my question with regards to this is how you see it as being different or an improvement or perhaps building on the work of the previously mentioned authors.