Definition:
Dean Leffingwell states “The Architectural Runway consists of the existing code, components, and technical infrastructure needed to implement near-term features without excessive redesign and delay.”
The architectural runway is one of the primary tools used to implement the agile architecture strategy, which provides the necessary technical foundation for developing business initiatives and implementing new Features and/or capabilities. Development of new features and capabilities consumes the architectural runway. Enablers support the activities needed to extend the Architectural Runway to provide future business functionality, which includes exploration, infrastructure, compliance and architecture development.
Architectural Runway is the existing technical infrastructure, code, necessary to support the implementation of upcoming features without excessive, delay-inducing, redesign.
Further Reading:
https://www.scaledagileframework.com/architectural-runway/
https://en.wikipedia.org/wiki/Agile_Architecture
https://www.scaledagileframework.com/enablers/