This article is the second in a series on how agile is being adopted in the U.S. defense industry. The first article discussed challenges specific to using agile in the defense industry, and why it is being adopted.
For any effort that uses the agile methodology, deciding "who is on the team" is a key step. The agile manifesto prioritizes individuals and interactions; for most users of agile, those interactions occur within a team. For example, the Scrum Framework is built around the idea of a "Development Team", which is limited to only those people who perform work on the product, and a "Scrum Team", which includes the Development Team plus the "Scrum Master", someone who represents (not manages) the team and removes roadblocks, and the "Product Owner", a single person who helps the team understand the purpose and value of the work the team is doing.
Within the U.S. defense industry, team-based development is widely used with agile, but there are a couple key challenges that lead to compromises. First, while in any team there will be a mix of skills and expertise, in defense programs there is a wide range of different engineering disciplines involved. On an aircraft program, there are engineers who are expert in aerodynamics, aircraft structure, power systems, equipment cooling, antenna placement on the outside of the aircraft (to avoid having antennas interfere with one another), electrical generation, and many others. There are also systems engineers who have responsibility for ensuring the pieces will come together as expected, and hardware engineers who identify off-the-shelf hardware that meets aircraft specifications, or perform custom hardware design. Within software engineering there are distinct skills for developers who create embedded real-time safety-critical software, those who create software for the mission system, and those who handle signal processing or communications systems. While every form of software development has its separations (e.g. "full stack" versus UI, service, and database developers), the distinctions in the defense industry are sharper because of the constraints on each type of software driven by hardware or certification requirements.
One reason for organizing into teams is the desire to build shared purpose and a shared desire for quality. It is important, to create that shared purpose, that the development team consist only of people who are responsible for the work, and who can understand and appreciate the work that each person brings to the team. Ideally, to work most effectively as a team, there should be significant skill overlap in the agile team so that team members can pick up some of the work when another team member is overloaded; otherwise, teams can be stuck waiting on one person, which is bad for efficiency and leads to dissatisfaction both for the people who are waiting and the person who is overloaded. So there is a difficult decision to make in terms of how "cross-functional" a team should be. On the one hand, a cross-functional team is less likely to have errors caused by failure of communication between engineering disciplines. On the other hand, a cross-functional team is probably less able to redistribute the workload to keep everyone busy.
A second challenge to agile team organization in the U.S. defense industry is that, while there are many smaller defense programs, it is common to have programs with dozens or hundreds of engineers working in parallel on the same system. There is a natural limit to the size of a team; as Fred Brooks pointed out in the Mythical Man-Month, increasing the size of the team increases the number of interactions that must occur for progress to continue; eventually this becomes counter-productive. In the Scrum Framework, a maximum size of 9 people is recommended.
This means that within the defense industry, most programs consist of multiple teams that must then coordinate in order to get the entire system built. A "Scrum of Scrums" is often used as a way to get people from different teams together to discuss the whole system. TheScaled Agile Framework (SAFe) creates more structure around the teams, including explicit roles for a system team and for architects. Either way, of course, there is still much less interaction between teams than there is inside teams.
There is an intersection between these two challenges: if it is necessary to divide up into multiple teams, should these teams be divided up by discipline (e.g. one or more teams of software engineers, one or more teams of hardware engineers), or by system function (e.g. one cross-functional team for the avionics, one for off-board communications)? Both approaches are used, but my sense (not backed by data) is that discipline teams are currently more prevalent. I believe there are a few reasons for this. First, it is difficult to create a close-working team when the work that each person is doing is quite different. Second, while ideally we would like to be able to work iteratively, there is a natural ordering to the work, as I discussed in the previous article. For example, the software team needs devices to be selected before work on device drivers can begin. So often different engineering disciplines are needed on a program at different times, making a single cross-functional team difficult to maintain. Third, in my experience software engineers are more likely to advocate agile methodologies, and in some organizations there is resistance to agile outside of software. In some cases this means that "software is doing agile" but other disciplines are using their traditional approaches. This works about as well as you would expect, but deserves its own article.
The key takeaway here is that while some programs in the defense industry keep their single-discipline teams under agile because of different rates of agile adoption, there are other, better reasons to keep single discipline teams. At the same time, I have seen the cross-functional team approach be successful. Without cross-functional teams, engineers have to commit more of their work to paper so that they can communicate it to other teams. This appears "better" to evaluators of the engineering process, because there is a feeling that the system is "well-documented" and therefore "well-engineered". However, this can be false quality, because the documents can be interpreted different ways, can become obsolete, or can be in conflict with each other. These kinds of documentation issues generally only become obvious in retrospect. Also, with single-discipline teams, there tends to be a great deal more up-front planning (e.g. requirements analysis, interface design), which can make the system less able to respond to inevitable changes in requirements or to discovery during implementation. With aircraft development, this often manifests as weight issues, because new functionality is being added to the aircraft, but it is very difficult to go back and remove or rework existing design decisions.
So how to balance these competing priorities? One approach I have seen work well is similar to the idea of the "Scrum of Scrums", but uses a "peer-to-peer" approach rather than a "reporting up" approach. The teams are organized mostly according to disciplines, so that within a team, work can be shared equally. In addition to their regular team role, each person also has a role as "liaison" to another team wherever there is an inter-dependency between teams. Within software, this might mean that one person on the user interface team is a liaison to the database team. The idea is to spread this responsibility out across the members of the team, both to balance the workload and to ensure that all members of the team see it as their responsibility to stay current on what other teams are doing. Where possible, the liaison attends any daily meetings of the other team, and of course serves as the first point of contact when questions arise.
Of course, responding to change is also a key value in agile, so this approach is not one-size-fits-all. Often, programs find their most productive organization by working iteratively to fix communication and efficiency issues, so that the right team structure develops as the program moves forward. The most important thing is to keep in mind the advantages and disadvantages of different ways of organizing large cross-functional teams, so that when problems show up, the cause is understood and they can be fixed.
Next time, I will discuss how iterative development using agile intersects with the traditional mentality of "milestone reviews", and what teams are doing to be more flexible.