CELL_SIM_UNPLUGGED (Zip)
Applicable alarms (1)
Likely outcomes — click to expand
Based on 10 missions where this alarm fired in the last 90 days as of 2026-10-13
Grounding vs discrepancy (of 4 ZERP issues filed on these missions)
Frequently co-occurring alarms (% of the 10 missions above)
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 cellular SIM card is not detected in an aircraft compute board.
Troubleshooting Steps
Section titled “Troubleshooting Steps”graph TD
power-cycle-the-aircraft-power-cycle-ai["<small><b>Step 1</b></small><br/>Action: Power cycle the aircraft: Power Cycl..."]
perform-preflight["<small><b>Step 2</b></small><br/>Action: Perform preflight."]
has-the-alarm-cleared{"<small><b>Step 3</b></small><br/>Question: Has the alarm cleared?"}
return-the-aircraft-to-service("<small><b>Step 4</b></small><br/>Reference: Return the Aircraft to service")
replace-the-compute-board["<small><b>Step 5</b></small><br/>Action: Replace the compute board UMM: Remove..."]
did-this-remedy-the-issue{"<small><b>Step 6</b></small><br/>Question: Did this remedy the issue?"}
return-the-aircraft-to-service-2("<small><b>Step 7</b></small><br/>Reference: Return the Aircraft to service")
escalate-to-embedded-linux-on-call{{"<small><b>Step 8</b></small><br/>Escalation: Escalate to P2 Embedded Linux On Call"}}
power-cycle-the-aircraft-power-cycle-ai --> perform-preflight
perform-preflight --> has-the-alarm-cleared
has-the-alarm-cleared -->|Yes| return-the-aircraft-to-service
has-the-alarm-cleared -->|No| replace-the-compute-board
replace-the-compute-board --> did-this-remedy-the-issue
did-this-remedy-the-issue -->|Yes| return-the-aircraft-to-service-2
did-this-remedy-the-issue -->|No| escalate-to-embedded-linux-on-call
style power-cycle-the-aircraft-power-cycle-ai fill:#dcfce7,stroke:#22c55e,color:#14532d
style perform-preflight fill:#dcfce7,stroke:#22c55e,color:#14532d
style has-the-alarm-cleared fill:#dbeafe,stroke:#3b82f6,color:#1e3a5f
style return-the-aircraft-to-service fill:#f3e8ff,stroke:#a855f7,color:#581c87
style replace-the-compute-board fill:#dcfce7,stroke:#22c55e,color:#14532d
style did-this-remedy-the-issue fill:#dbeafe,stroke:#3b82f6,color:#1e3a5f
style return-the-aircraft-to-service-2 fill:#f3e8ff,stroke:#a855f7,color:#581c87
style escalate-to-embedded-linux-on-call fill:#fef3c7,stroke:#f59e0b,color:#78350f Hover or focus a block to preview it. Select the block to keep the preview open.
UMM: Remove Flight Compute Assembly
UMM: Install Flight Compute Assembly
Resolution note
This plaintext block is ready to paste into the Resolution Note field on the ZERP issue you're working. The permalink below gives engineering review access to the full step-by-step timeline including any back-navigation; share it if the case needs a deeper look.
Permalink:
Session is too large to fit in a URL. Use Download session JSON to share the timeline out-of-band.
Did this guide help you get unblocked?
Open suggestions
There are no open suggestions.
Open pull requests
There are no open pull requests.