Design and development planning is needed to ensure that the design process is appropriately controlled and that device quality objectives are met. The plans must be consistent with the remainder of the design control requirements. The following elements would typically be addressed in the design and development plan or plans:
- Description of the goals and objectives of the design and development program; i.e., what is to be developed
- Delineation of organizational responsibilities with respect to assuring quality during the design and development phase to include interface with any contractors Identification of the major tasks to be undertaken, deliverables for each task, and individual or organizational responsibilities (staff and resources) for completing each task
- Scheduling of major tasks to meet overall program time constraints
- Identification of major reviews and decision points
- Selection of reviewers, the composition of review teams and procedures to be followed by reviewers
- Controls for design documentation
- Notification activities
Planning enables management to exercise greater control over the design and development process by clearly communicating policies, procedures and goals to members of the design and development team. Planning also provides a basis for measuring conformance to quality system objectives.
Design activities should be specified at the level of detail necessary for carrying out the design process. The extent of design and development planning is dependent on the size of the developing organization and the size and complexity of the product to be developed. Some manufacturers may have documented policies and procedures which apply to all design and development activities. For each specific development program, such manufacturers may also prepare a plan which spells out the project-dependent elements in detail and incorporates the general policies and procedures by reference. Other manufacturers may develop a comprehensive design and development plan which is specifically tailored to each individual project.
In summary, the form and organization of the planning documents are less important than their content. The following paragraphs discuss the key elements of design and development planning.
The management responsibility section of the quality system requirements requires management to establish a quality policy and implement an organizational structure to ensure quality. These are typically documented in a quality manual or similarly named document. In some cases, however, the design and development plan rather than the quality manual is the best vehicle for describing organizational responsibilities relative to design and development activities. The importance of defining responsibilities with clarity and without ambiguity should be recognized. When input to the design is from a variety of sources, their interrelationships and interfaces (as well as the pertinent responsibilities and authorities) should be defined, documented, coordinated and controlled. This might be the case, for example, if a multidisciplinary product development team is assembled for a specific project, or if the team includes suppliers, contract manufacturers, users, outside consultants or independent auditors.
The plan establishes, to the extent possible:
- The major tasks required to develop the product
- The time involved for each major task
- The resources and personnel required
- The allocation of responsibilities for completing each major task
- The prerequisite information necessary to start each major task and the interrelationship between tasks
- The form of each task output or deliverable
- Constraints, such as applicable codes, standards, and regulations
Tasks for all significant design activities, including verification and validation tasks, should be included in the design and development plan. For example, if clinical trials are anticipated, there may be tasks associated with appropriate regulatory requirements.
For complex projects, rough estimates may be provided initially, with the details left for the responsible organizations to develop. As development proceeds, the plan should evolve to incorporate more and better information.
The relationships between tasks should be presented in such a way that they are easily understood. It should be clear which tasks depend on others, and which tasks need to be performed concurrently. Planning should reflect the degree of perceived development risk; for example, tasks involving new technology or processes should be spelled out in greater detail, and perhaps be subjected to more reviews and checks, than tasks which are perceived as routine or straightforward.
The design and development plan may include a schedule showing starting and completion dates for each major task, project milestone or key decision points. The method chosen and the detail will vary depending on the complexity of the project and the level of risk associated with the device. For small projects, the plan may consist of only a simple flow diagram or computer spreadsheet. For larger projects, there are a number of project management tools that are used to develop plans. Three of the most commonly used are the Program Evaluation and Review Technique (PERT), the Critical Path Method (CPM), and the Gantt chart. Software is available in many forms for these methods. When selecting these tools, be careful to choose one that best fits the needs of the project. Some of the software programs are far more complex than may be necessary.
Unless a manufacturer has experience with the same type of device, the plan will initially be limited in scope and detail. As work proceeds, the plan is refined. Lack of experience in planning often leads to optimistic schedules, but slippage may also occur for reasons beyond the control of planners. Some examples include personnel turnover, materiel shortage or unexpected problems with a design element or process. Sometimes the schedule can be compressed by using additional resources, such as diverting staff or equipment from another project, hiring a contractor or leasing equipment.
It is important that the schedule be updated to reflect current knowledge. At all times, the plan should be specified at a level of detail enabling management to make informed decisions and provide confidence in meeting overall schedule and performance objectives. This is important because scheduling pressures have historically been a contributing factor in many design defects which caused injury. To the extent that good planning can prevent schedule pressures, the potential for design errors is reduced.
However, no amount of planning can eliminate all development risk. There is inherent conflict between the desire to maximize performance and the need to meet business objectives, including development deadlines. In some corporate cultures, impending deadlines create enormous pressure to cut corners. Planning helps to combat this dilemma by ensuring management awareness of pressure points. With awareness, decisions are more likely to be made with appropriate oversight and consideration of all relevant factors. Thus, when concessions to the clock must be made, they can be justified and supported.