Planning

---
name: planning
description: "Use when planning DO-178C software certification for airborne systems or equipment: determine the software level or DAL (A-E) from failure-condition severity, draft the PSAC (Plan for Software Aspects of Certification), and scope planning-phase artifacts such as the PSAC, SDP, SVP, SCM, and SQA plans. Covers ARP4754A FDAL/IDAL allocation and ARP4761A severity-to-DAL propagation, including coverage-depth implications per level: A requires MC/DC, B requires decision coverage, C requires statement coverage, D and E require none. Trigger: DO-178C planning, PSAC, software level determination, DAL assignment, development assurance, certification planning, ARP4754A, ARP4761A, airborne software certification."
license: Apache-2.0
compliance: STANDARDS-REF
standards:
  - id: DO-178C
    reference-only: true
  - id: ARP4754A
    reference-only: true
  - id: ARP4761A
    reference-only: true
gated: false
domain: avionics
pack: avionics
compatibility: "agentskills.io SKILL.md; any SKILL.md host (Claude Code, Hermes, OpenClaw)"
metadata:
  domain: avionics
  subdomain: do178c
  tags: [do-178c, dal, psac, certification, arp4754a, arp4761a, software-levels]
  version: 0.1.0
  author: Aero Agent Skills
---

# DO-178C Planning (avionics/do178c/planning)

Use when the task is DO-178C planning-phase work: drafting a PSAC,
determining the software level (DAL) for a function or item, or scoping
planning-phase artifacts (PSAC, SDP, SVP, SCM, SQA plans).

## Domain quick reference

- Software levels (DO-178C): A = Catastrophic, B = Hazardous, C = Major,
  D = Minor, E = No safety effect.
- ARP4754A splits development assurance: FDAL (function) vs IDAL (item);
  an item's IDAL is the highest FDAL among the functions it implements.
- ARP4761A propagates failure-condition severity to DAL.
- Coverage depth scales with DAL: A = 100% MC/DC, B = 100% decision,
  C = 100% statement, D/E = none required.
- Accepted means of compliance: AC 20-115D (software), AC 20-174 (ARP4754A).

## Workflow

1. Confirm certification basis and applicable standards.
2. Determine failure-condition severity per ARP4761A (FHA/PSSA inputs).
3. Allocate DAL / FDAL / IDAL per ARP4754A + ARP4761A.
4. Map DAL to DO-178C software level and objectives tables.
5. Draft PSAC and planning-phase artifacts.

## Pitfalls

- DAL from severity alone without FDAL/IDAL split.
- Coverage depth mismatched to level (A requires MC/DC, not statement).
- Traceability gaps (no derived requirements).

## Stop gate: human sign-off required

The agent drafts; it does not decide. Stop and hand the draft to a named
human before any of these leave the working folder:

- The software level assigned to each function or item. The agent may
  propose it with the severity rationale, but the level stands only once
  the responsible engineer has agreed it with the safety assessment team.
- The PSAC and the other planning-phase plans submitted to the
  certification authority or its designee.
- Any deviation, alternative method, or reduced objective set.

Mark every such output as a draft, list the open questions for the
reviewer, and end with the line: STOP: human sign-off required before
submission.

## Behavior contract (gate 3)

This skill ships its own contract test, like every skill in the library:
scripts/test_do178c_levels.py against scripts/do178c_levels.py (stdlib
unittest, offline). Run: python3
skills/avionics/do178c/planning/scripts/test_do178c_levels.py

## Compliance

- Standards referenced, not reproduced: DO-178C / ARP4754A / ARP4761A text is
  proprietary (RTCA/SAE); summary-only per standards-map.yaml and brief 06.
- Revision note: ARP4754B (2023) supersedes ARP4754A; this skill keys to
  ARP4754A as the certification-baseline revision (FAA AC 20-174 cites A);
  see standards-map.yaml arp4754a.revision_decision.
- compliance: STANDARDS-REF, gated: false.