Definition
An area navigation (RNAV) system that the FAA has determined meets the accuracy, integrity, and functional requirements needed to be used in place of conventional ground-based navigation aids for a given phase of flight or specific procedure. A suitable RNAV system can be used to navigate on conventional routes and procedures, including substituting for an out-of-service ground-based navaid, identifying named fixes, and flying course reversals or holding patterns, provided the operation is permitted by the aircraft's certification and operating rules.
Plain English
An onboard navigation system that the FAA accepts as good enough to take the place of traditional ground stations like VORs and NDBs for certain tasks. If your RNAV system qualifies as 'suitable,' you can use it to fly the route, find the fixes, and shoot the approach even when the older ground equipment isn't available.
Context Anchor
You will see this term when deciding whether the aircraft’s navigation equipment may be used for a route, arrival, departure, or approach that requires RNAV capability.
Derivation
Suitable' here is the everyday word, but the FAA uses it in a specific regulatory sense -- meaning 'meets the published criteria.' It is not a casual judgment by the pilot; it is a defined status based on equipment certification and operational approval.
Why Pilots Care
Using a system that does not qualify can cause navigation errors, failed approaches, or violations during IFR or oceanic operations.
Intuition Check
“Suitable” does not just mean “available” or “nice to have.” In this context it means approved, working, and capable of meeting the requirements for that specific operation.
Example Sentence 1
Because the aircraft was equipped with a suitable RNAV system, the pilot was able to identify the intersection even though the cross-radial VOR was out of service.
Example Sentence 2
For the oceanic crossing, dispatch confirmed the aircraft carried a suitable RNAV system capable of the required accuracy.