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Zipline Zipline Service Documentation

    DOWNWARD_SPEED_FAILURE

    published Last Updated: Oct 9, 2026 HW: all
    Applicable alarms (1)
    DOWNWARD_SPEED_FAILURE
    Likely outcomes (6 missions, 10 issues) — click to expand

    Based on 6 missions where this alarm fired in the last 90 days as of 2026-10-13

    Grounding vs discrepancy (of 10 ZERP issues filed on these missions)

    Grounding 0% (0 of 10 issues) Discrepancy 100% (10 of 10 issues)

    Frequently replaced parts

    Part P/N Removals
    BATTERY ASSY, ZIP, P2 27158 48
    NOSECONE ASSY, ZIP, P2 26121 9
    LEFT DOOR ASSY, DROID, P2 21830 8
    RIGHT DOOR ASSY, DROID, P2 21827 8
    PARALAND ASSY, ZIP, P2 18480 7

    Aggregated from fleet operations and refreshed daily. Individual outcomes may vary by site and configuration.

    Background

    Section titled “Background”

    This alarm is triggered when the navigation downward velocity estimate exceeds a set limit. In flight, this will trigger a paraland.

    The underlying reasons could include but is not limited to: control instability, hardware faults, or poor nav state estimates.

    Troubleshooting Steps

    Section titled “Troubleshooting Steps”
    1 escalation
    Escalate to P2 Zip Controls On Call

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    Topic history
    1. 2026-10-07 Susan Minne Bulk/mechanical change
      Replace individual guide ownership with system technical contacts
      Commit dca5a1a
    2. 2026-09-24 Susan Minne Bulk/mechanical change
      chore: backfill aircraft owner identities batch 2
      Commit 6ca6807
    3. 2026-09-23 Susan Minne Bulk/mechanical change
      docs: remove obsolete Confluence metadata
      Commit 2d5374e
    4. 2026-09-13 Susan Minne Bulk/mechanical change
      feat: add MX approval metadata to topics
      Commit 406a785
    5. 2026-06-12 Susan Minne Bulk/mechanical change
      Update troubleshooting topics and escalation paths
      Commit 166da10
    6. 2026-05-28 Susan Minne Bulk/mechanical change
      Remove redundant topic applicability banners
      Commit e561ad0
    7. 2026-05-10 Susan Minne Bulk/mechanical change
      Reviewed migrated topics. Edited as needed. Published.
      Commit 6199e3f
    8. 2026-05-06 Gavin Edwards Bulk/mechanical change
      Remove redundant Engineer Owner table from topic body (#298)
      Commit 1619f07 PR #298
    9. 2026-05-04 Gavin Edwards Bulk/mechanical change
      Add 23 new topics (batch 5) + path-prop fixes on 33 existing topics
      Commit 05b76c0
    10. 2026-04-15 Gavin Edwards Bulk/mechanical change
      Replace topic corpus: 388 LLM-regenerated topics (round 1)
      Commit f950bfa
    11. 2026-04-14 Gavin Edwards Bulk/mechanical change
      Tag all 427 topics draft with DO NOT USE warning admonition
      Commit 1783498
    12. 2026-04-08 Gavin Edwards Bulk/mechanical change
      Refactor: single TopicPage component replaces 5 individual imports
      Commit 49b5720
    13. 2026-04-07 Gavin Edwards Bulk/mechanical change
      Import 19 more topics, add FlowVisualizer to all topics
      Commit b2fafb6
    14. 2026-04-07 Gavin Edwards Bulk/mechanical change
      GitHub source links, homepage revamp, Getting Started guides
      Commit d83c157
    Baseline import
    Initial import into service_docs
    Imported by Gavin Edwards on 2026-04-07
    Organize topics by category, import 10 more, coverage auto-maintenance, AI guardrails
    Commit f5a310c
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