CELL_MODEM_NOT_CONNECTED
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Applicable alarms (1)
CELL_MODEM_NOT_CONNECTED
Likely outcomes — click to expand
Based on 122,443 missions where this alarm fired in the last 90 days as of 2026-10-13
Grounding vs discrepancy (of 1,238 ZERP issues filed on these missions)
Top work orders
- EV3: Inspect Aircraft after Droid Left Behind (DLB) · MAINTENANCE_ACTION 117
- Inspect Droid after Droid Left Behind (DLB) · MAINTENANCE_ACTION 78
- Reset Droid after DLB · REPAIR 63
- Offload Droid Logs after DLB · ADMINISTRATIVE 33
- V4 Zipping Point: Inspect Zipping Point after Droid Left Behind (DLB) - Ranger · MAINTENANCE_ACTION 29
Frequently replaced parts
| Part | P/N | Removals |
|---|---|---|
| ASSY, SPOOL AND LINE, DOCKING FIN | 48477 | 417 |
| SERVO, ASSY, UNIVERSAL, P2 | 20398 | 197 |
| CW/CCW HOVER MOTOR ASSY, ZIP, P2 | 19607 | 174 |
| PREPPED HOVER HARNESSING, STBD, ZIP, P2 | 0117583 | 152 |
| WING ASM FULL, TRIAX, NO DAA, PORT(LH), ZIP, P2 | 24762 | 150 |
Frequently co-occurring alarms (% of the 122,443 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 cell modem on the Aircraft is not connected to the cellular network.
Excerpt include: “Cellular network caveats” from CORRECTIONS_REDUNDANCY_FAILURE
Troubleshooting Steps
Section titled “Troubleshooting Steps”graph TD
is-cell-sim-unplugged-asserted{"<small><b>Step 1</b></small><br/>Question: Is CELL_SIM_UNPLUGGED asserted on t..."}
follow-cell-sim-unplugged-guide["<small><b>Step 2</b></small><br/>Action: Resolve CELL_SIM_UNPLUGGED using C..."]
is-the-alarm-affecting-the-fleet-or-gen{"<small><b>Step 3</b></small><br/>Question: Is the alarm affecting the fleet, or ..."}
there-maybe-a-transient-issue-with-the["<small><b>Step 4</b></small><br/>Action: There maybe a transient issue with th..."]
did-the-issue-resolve-after-waiting-10{"<small><b>Step 5</b></small><br/>Question: Did the issue resolve?"}
return-the-aircraft-to-service("<small><b>Step 6</b></small><br/>Reference: Return the Aircraft to service")
escalate-to-embedded-linux-on-call{{"<small><b>Step 7</b></small><br/>Escalation: Escalate to P2 Embedded Linux On Call"}}
power-cycle-the-aircraft-power-cycle-ai["<small><b>Step 8</b></small><br/>Action: Power cycle the Aircraft Power Cycle..."]
perform-preflight["<small><b>Step 9</b></small><br/>Action: Perform preflight."]
has-the-alarm-cleared{"<small><b>Step 10</b></small><br/>Question: Has the alarm cleared?"}
return-the-aircraft-to-service-2("<small><b>Step 11</b></small><br/>Reference: Return the Aircraft to service")
escalate-to-embedded-linux-on-call-2{{"<small><b>Step 12</b></small><br/>Escalation: Escalate to P2 Embedded Linux On Call"}}
is-cell-sim-unplugged-asserted -->|Yes| follow-cell-sim-unplugged-guide
is-cell-sim-unplugged-asserted -->|No| is-the-alarm-affecting-the-fleet-or-gen
follow-cell-sim-unplugged-guide --> is-the-alarm-affecting-the-fleet-or-gen
is-the-alarm-affecting-the-fleet-or-gen -->|Yes| there-maybe-a-transient-issue-with-the
is-the-alarm-affecting-the-fleet-or-gen -->|No| power-cycle-the-aircraft-power-cycle-ai
there-maybe-a-transient-issue-with-the --> did-the-issue-resolve-after-waiting-10
did-the-issue-resolve-after-waiting-10 -->|Yes| return-the-aircraft-to-service
did-the-issue-resolve-after-waiting-10 -->|No| escalate-to-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-2
has-the-alarm-cleared -->|No| escalate-to-embedded-linux-on-call-2
style is-cell-sim-unplugged-asserted fill:#dbeafe,stroke:#3b82f6,color:#1e3a5f
style follow-cell-sim-unplugged-guide fill:#dcfce7,stroke:#22c55e,color:#14532d
style is-the-alarm-affecting-the-fleet-or-gen fill:#dbeafe,stroke:#3b82f6,color:#1e3a5f
style there-maybe-a-transient-issue-with-the fill:#dcfce7,stroke:#22c55e,color:#14532d
style did-the-issue-resolve-after-waiting-10 fill:#dbeafe,stroke:#3b82f6,color:#1e3a5f
style return-the-aircraft-to-service fill:#f3e8ff,stroke:#a855f7,color:#581c87
style escalate-to-embedded-linux-on-call fill:#fef3c7,stroke:#f59e0b,color:#78350f
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-2 fill:#f3e8ff,stroke:#a855f7,color:#581c87
style escalate-to-embedded-linux-on-call-2 fill:#fef3c7,stroke:#f59e0b,color:#78350f Hover or focus a block to preview it. Select the block to keep the preview open.
1 question
Is
CELL_SIM_UNPLUGGED asserted on the affected compute? Check this alarm before troubleshooting the cellular connection. 2 action
Resolve
CELL_SIM_UNPLUGGED using CELL_SIM_UNPLUGGED (Zip) first. If the cellular connection issue persists after the SIM alarm is resolved, continue this guide. 3 question
Is the alarm affecting the fleet, or generally more than a single vehicle at the same time?
4 action
There maybe a transient issue with the cell network.
Wait 10 minutes and then resend the mission. Did the issue resolve?
Wait 10 minutes and then resend the mission. Did the issue resolve?
5 question
Did the issue resolve?
6 reference
Return the Aircraft to service
7 escalation
Escalate to P2 Embedded Linux On Call
8 action
Power cycle the Aircraft Power Cycle Aircraft.
9 action
Perform preflight.
10 question
Has the alarm cleared?
11 reference
Return the Aircraft to service
12 escalation
Escalate to P2 Embedded Linux On Call
Resolution note
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