ARINC 717¶

Flight data acquisition and recording interface commonly associated with DFDAU-to-DFDR streams.

Identity¶

Flight data acquisition and recording interface commonly associated with DFDAU-to-DFDR streams.

What This Protocol Teaches¶

• Some buses are not for control; they are for memory.
• It teaches how to inspect frames/subframes, words per second, sync words without mistaking field extraction for meaning.
• It keeps observer inference separate from system truth.

Operational Context¶

ARINC 717 appears in commercial-aviation, flight-data contexts and is modeled in the atlas at the data-link, recording layer(s). The binder treats it as an inspection surface: what evidence appears, what timing matters, and what outside authority is required before assigning meaning.

draft-structure-only: this is not yet a final-copy binder page. It has an atlas-grounded teaching hook and source notes, but still needs a stronger worked trace, page-specific ambiguity case, and reviewer-validated visual before promotion.

A Concrete Artifact¶

# synthetic flight-data frame shape
subframe=1 word[001]=0x0123 word[002]=0x0456 ...

Synthetic offline sample for explanation; not a real operational trace or live-system instruction.

Worked Decode¶

1. Treat subframe=1 as the boundary of one synthetic flight-data-recording fragment.
2. word[001]=0x0123 and word[002]=0x0456 are position-indexed words, not named measurements.
3. Subframe and word index are the first authority hook: meaning depends on a frame map for the installation.
4. The ellipsis is a deliberate cue that a recorder frame is bigger than this teaching artifact.
5. A passive observer can discuss subframe cadence and missing words without assigning flight parameters.

Field Layout / Anatomy¶

Visual Model¶

Timing And Authority¶

Timing and authority depend on the flight-data-recording-bus role: scheduled, polled, arbitrated, transmitted, or logged evidence should not be read as the same kind of truth. Semantic authority is external to the raw artifact unless the artifact is itself a description or capture format; even then, provenance determines whether the description should be trusted.

Bytes rarely explain themselves. Name the source that defines meaning before naming engineering values: standard metadata, label table, DBC, PGN/SPN definition, object dictionary, register map, DID catalog, LDF, ARXML, channel metadata, or vendor profile.

Failure And Ambiguity¶

• A word index is not a parameter without the frame map.
• Recorder cadence can hide mode-dependent subframes or missing segments.
• A copied frame layout from another aircraft can create plausible false measurements.

Observer Lesson¶

A passive observer can usually infer artifact boundaries, repeated structure, cadence, missingness, and candidate state transitions. The observer usually cannot prove physical truth, application intent, complete system state, or engineering-unit meaning without semantic authority and timing provenance.

Python Model¶

No current runtime example is claimed for this draft page. Keep reader claims at the artifact and source level until a separate implementation plan adds a tested model.

Local Teaching Notes¶

The artifact and diagrams are synthetic teaching material. The page intentionally omits conformance timing tables, electrical design detail, proprietary configuration, and exhaustive standard behavior.

Source Confidence¶

Source confidence is high for scope and terminology, with semantic claims limited to public metadata, public source notes, and synthetic teaching artifacts.

Source Notes¶

References¶

Public Sources¶

• SAE ITC / ARINC
• ARINC 717 Flight Data Acquisition and Recording System — canonical-standard.