VFS Regulatory Readiness Level Calculator
The Vertical Flight Society (VFS) is pleased to make the RRL Calculator available as a free resource to the vertical flight and broader aviation community.
The RRL Calculator is a downloadable Excel-based self-assessment tool designed to help organizations understand the challenge and evaluate their progress toward Type Certification and Operational Approval using the Regulatory Readiness Level (RRL) framework.
What “RRL” means (and what it covers)
Regulatory Readiness Level (RRL) is an assessment framework aligned to civil aviation authorities (e.g., FAA, EASA) and to defined operational concepts (e.g., FAA Part 135 operations). RRL isn’t “how mature is the technology,” it’s “how ready is the program for the regulatory path and the intended operation.”
RRL is applicable across the full aircraft landscape:
- VTOL, STOL and CTOL Aircraft
- Electric, hybrid, turbine, and internal combustion
- New aircraft and legacy aircraft (including aircraft in long-running certification efforts)
- Type Certification and, over time, Supplemental Type Certificates (STCs)
The RRL Checklist and the RRL Calculator (how they relate)
The RRL Checklist is the foundational reference, and the RRL Calculator is a working tool developed to help teams apply the checklist consistently, discuss inputs, and visualize results in a structured way.
Because the Calculator is based on the Checklist, improvements to one will be coordinated with the other to maintain alignment.
The original RRL Checklist was developed by Honeywell Aerospace as part of the early development of the Regulatory Readiness Level framework. The VFS RRL Calculator is not a Honeywell product or tool. The Calculator is provided by VFS as an independent community resource to support discussion and understanding of regulatory readiness.
Useful resources:
- Honeywell RRL Checklist
- FAA Supplemental Type Certificates (STC) overview
- hover.vtol.org (discussion and feedback)
What the RRL Calculator is (and is not)
The RRL Calculator is:
- A downloadable Excel workbook
- A structured self-assessment and internal discussion tool
- Designed to be revisited over time as a program progresses (and sometimes backtracks)
The RRL Calculator is not:
- A regulatory decision tool
- A substitute for direct engagement with FAA/EASA (or other authorities)
- A guarantee of certification outcome or timeline
The value is often in the debate it forces: teams must confront the full scope of regulatory work and document where they truly stand.
How to Use It
Many organizations will maintain separate files for multiple programs and update them as evidence changes.
Vision and where this goes next
The long-term vision is for RRL to expand beyond today’s initial alignment to support:
- Additional authorities (e.g., UK CAA, China CAAC, Transport Canada, ANAC, UAE GCAA, and others)
- Broader operational constructs (beyond the initial focus areas)
- UAS certification/operational pathways
- More explicit extensions for STCs and modifications to existing aircraft
Feedback, questions, and discussion (VFS Hover)
VFS welcomes technical feedback, suggested refinements, and lessons learned from real program use. Please join the discussion on the VFS Hover Community (login required).
This is the preferred place to ask questions, propose improvements, and help drive consensus as the framework matures.
A Community Tool
The RRL Calculator represents a collaborative effort among certification experts, industry leaders, and VFS technical volunteers. It is intended as a practical aid to improve transparency, discipline, and shared understanding in certification readiness discussions.
VFS is proud to make this tool available to both members and non-members in support of advancing vertical flight.