Part 23 navigation
Part 23 certification basis support for navigation equipment
This support connects a navigation system's evidence to the Part 23 certification basis of the normal-category aircraft it is being installed on. Suppliers and modifiers use it when a receiver, flight-management, or area-navigation unit was designed to a performance standard but the basis for the target aircraft asks for more than the standard alone answers. The work checks sensor input integrity, database and currency handling, the software level claimed, and alignment with the applicable minimum operational performance standards, then reconciles all of it to the named basis paragraphs. You receive a basis map for the navigation function, a list of items the evidence does not yet reach, and an ordered path to close them.
When this review is needed
- A navigation unit built to a performance standard is going into a normal-category aircraft and its evidence has to answer the aircraft's Part 23 basis.
- An operational credit such as an approach capability is being claimed and the basis behind it has to be substantiated, not assumed from the box specification.
- A finding questions whether the database currency and integrity handling meet the intended navigation function.
- The software level asserted for the navigation computation has to be reconciled with the failure effect the basis assigns it.
The problem
Navigation equipment carries a performance case built to a minimum operational performance standard, and that case answers the standard, not the aircraft basis. A normal-category installation adds questions the standard leaves open: how sensor inputs are validated, how a stale or corrupt database is caught, and whether the software level matches the operational credit being claimed. Those threads sit in different documents, and the basis paragraph that ties them together is usually the one nobody has traced.
What gets reviewed
- The Part 23 basis paragraphs the navigation function answers, at the aircraft's amendment level
- Sensor input sources and the validation the receiver applies before the position is used
- Navigation database currency, integrity, and the handling of an out-of-date or corrupt load
- The claimed software level against the failure effect of a misleading navigation output
- Alignment with the applicable minimum operational performance standard for the intended credit
- The gap between demonstrated coverage and coverage the package assumes from the standard
What gets validated
- Each navigation-related basis paragraph has evidence assigned rather than an implicit lean on the performance standard
- Sensor input validation is substantiated for the failure modes a wrong position would create
- Database currency and integrity handling is tested, including the response to a stale or corrupt load
- The software level claimed matches the failure effect of a misleading navigation output for this aircraft
- The operational credit claimed traces to the minimum operational performance standard it depends on
Evidence normally required
- The certification basis for the normal-category aircraft and its amendment level
- The navigation equipment performance and environmental qualification reports
- The software lifecycle summary and the assigned software level
- The navigation database architecture and currency-handling description
- The operational credit being sought and the performance standard behind it
Common discrepancies
- An operational credit claimed with no trace to the performance standard that supports it
- Database integrity handling that is described but never tested against a corrupt load
- A software level asserted below what a misleading navigation output would require
- Sensor input validation assumed from the box specification rather than substantiated for the install
What is at stake
A navigation package that leans on the performance standard alone can pass its own bench tests and still miss the basis items that gate the operational credit. When a finding surfaces a gap in database integrity or software level late, the fix reaches back into the software assurance evidence or the sensor-validation logic, and re-opening either is expensive once the installation is otherwise closed.
Move from findings to resolution
Identify gaps against the means of compliance.
How the work runs
Fix the credit and basis
Establish the operational credit sought and the Part 23 basis paragraphs the navigation function must answer for this aircraft.
Trace inputs and data
Follow sensor validation and database handling into the evidence and mark where the trace to the basis stops.
Check level against effect
Reconcile the claimed software level with the failure effect of a misleading navigation output under this credit.
Order the closure
Prioritize the gaps that gate the credit and deliver a basis map for the matrix.
What the buyer receives
- A basis map linking each relevant Part 23 paragraph to the navigation evidence behind it
- A gap list of basis items the current evidence does not reach, with what each requires
- A closure sequence prioritizing the gaps that gate the operational credit
Who uses the output
- Certification leads building the navigation compliance argument for a normal-category submittal
- Engineering teams reconciling the software level and database handling to the basis
- Compliance managers defending the operational credit against a finding
How the work fits into the transaction or program
The mapping bridges the navigation performance case and the aircraft-level submittal, turning a MOPS-based argument into basis-level compliance for the normal-category aircraft. The gap list steers the remaining software and database work, and the basis map populates the compliance matrix the applicant carries forward.
Start with a single asset
Confirm requirements trace through verification.
Aircraft-specific considerations
The operational credit a normal-category aircraft can carry depends on its equipage and its basis amendment level, so the same navigation unit supports different credits on different types. The mapping is scoped to the credit actually being sought on this aircraft, because a receiver adequate for one approach capability may leave basis items open for a more demanding one.
Jurisdiction-specific considerations
FAA and EASA reference navigation performance standards that mostly align but differ in accepted operational credits and in which advisory material is invoked, so a navigation argument accepted under one basis can need supplement under the other. The mapping flags where the credit and its supporting standard change between authorities.
Regulatory limits
The work reconciles navigation evidence to the basis and marks the shortfalls. It grants no operational credit, makes no compliance finding, and issues no approval. The authority grants the credit and the applicant owns the claim.
What this review does not cover
- Granting or approving any operational credit or navigation authorization
- Running the navigation performance or flight-test campaign itself
- Any airworthiness determination on the installed navigation equipment
Specific to this review
- The operational credit, not the receiver, drives the basis: the same navigation unit answers different Part 23 items depending on the approach or area-navigation capability being claimed.
- Database integrity handling is the item most often described and least often tested, yet a stale or corrupt load is exactly the failure the basis is guarding against.
- A navigation software level set to the box's original program can undershoot the failure effect once an operational credit raises the stakes on a misleading output.
Sources
U.S. Government (eCFR). Type certificates, STCs (Subpart E), TSO authorizations (Subpart O), PMA (Subpart K), and export airworthiness approvals (Subpart L).
Federal Aviation Administration. FAA type certification process, certification basis establishment, and compliance findings.
SAE International. Development assurance process at aircraft and system level, including requirements capture and validation.
Frequently asked questions
The unit meets its MOPS. Why isn't that the whole compliance story?
A MOPS defines minimum performance for the equipment. The Part 23 basis asks how the installed navigation function meets the aircraft's paragraphs and supports the operational credit you are claiming. The mapping shows where meeting the MOPS still leaves basis items open.
Relevant glossary terms
Related pages
Where this fits
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