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Zipline Zipline Service Documentation

    ZipNav Watchdog General Troubleshooting

    published Last Updated: Oct 9, 2026 HW: all
    Applicable alarms (1)
    ZIPNAV_WATCHDOG
    Likely outcomes (0 missions) — click to expand

    Based on 0 missions where this alarm fired in the last 90 days as of 2026-10-13

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

    Section titled “Related Search Phrases”

    This issue may also be described as “Watchdog(s) Inactive: ZipNav”

    Background

    Section titled “Background”

    This watchdog fires when navigation is not publishing necessary information on Compute A or B. This is usually due to required services (like GNSS, IMU, etc) not providing required information to navigation.

    Troubleshooting Steps

    Section titled “Troubleshooting Steps”

    Can we see satellites with both receivers?

    Section titled “Can we see satellites with both receivers?”

    Check gnss_residuals.cn0 from the debug.gpsins topic, along with num_satellites_used from fusion_engine.gnss_info topic, from Compute A and B.

    Is there a clear drop in cn0 values?

    Steps

    There is likely a source of interference nearby, or an electrical/antenna issue.

    Refer to troubleshooting steps in this guide: GNSS_A_DEGRADED and GNSS_B_DEGRADED | Troubleshooting Steps

    Example investigation

    This plot shows a clear loss of signal for the Compute B receiver, indicating an issue with it’s antenna.

    newplot (12).png

    If not, continue to the next section.

    GPSINS Checks

    Section titled “GPSINS Checks”

    Examine debug.gpsins.update_flags from Compute A and B.

    Is HAS_PIM_FOR_EVERY_EPOCH false?

    Steps

    The IMU on the corresponding compute is likely misbehaving.

    If the IMU_TIMESTAMP_ERROR_HIGH alarm is set, follow IMU_TIMESTAMP_ERROR_HIGH.

    Otherwise, escalate to Linux Embedded.

    Is HAS_ALL_SIGNALS_ON_STARTUP and/or HAS_ALL_SIGNALS_ON_STARTUP_SECONDARY true?

    Steps

    There is an issue with one or more GNSS receiver.

    Determining which receiver(s)

    HAS_ALL_SIGNALS_ON_STARTUP points to the receiver local to the compute the message is from. HAS_ALL_SIGNALS_ON_STARTUP_SECONDARY points to the other compute’s receiver.

    • /compute_a.debug.gpsins.update_flags
      • HAS_ALL_SIGNALS_ON_STARTUP: Compute A’s GNSS receiver
      • HAS_ALL_SIGNALS_ON_STARTUP_SECONDARY: Compute B’s GNSS receiver
    • /compute_b.debug.gpsins.update_flags
      • HAS_ALL_SIGNALS_ON_STARTUP: Compute B’s GNSS receiver
      • HAS_ALL_SIGNALS_ON_STARTUP_SECONDARY: Compute A’s GNSS receiver

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    Topic history
    1. 2026-10-07 Susan Minne Bulk/mechanical change
      Replace individual guide ownership with system technical contacts
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    2. 2026-09-24 Susan Minne Bulk/mechanical change
      chore: backfill aircraft owner identities batch 4
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    3. 2026-09-23 Susan Minne Bulk/mechanical change
      docs: remove obsolete Confluence metadata
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    4. 2026-09-13 Susan Minne Bulk/mechanical change
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      Review of migrated topics and changed to published
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    6. 2026-05-06 Gavin Edwards Bulk/mechanical change
      Remove redundant Engineer Owner table from topic body (#298)
      Commit 1619f07 PR #298
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      Apply post-process script fixes to batch topics + procedures
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