Safety System Alarms ([SquibControlAlarm])
Viewing this guide for
Applicable alarms (46)
CONTROL_FAILURECOMMUNICATION_FAILURETIMED_OUT_WAITING_FOR_POWER_FAILUREDRIVER_UNEXPECTED_SYSTEM_STATE_FAILUREDRIVER_UNEXPECTED_FEN_STATE_FAILUREBACKUP_POWER_FAILUREDRIVER_FAULT_STATUS_BIT_ASSERTEDDRIVER_POWER_FAILUREDRIVER_CLOCK_FAILUREDRIVER_OTP_CRC_FAILUREDIAGNOSTIC_TEST_FAILUREDIAGNOSTIC_TEST_TIMEOUT_FAILUREVRCM_TEST_FAILURELEAKAGE_TEST_FAILURESHORT_BETWEEN_LOOPS_TEST_FAILURECONTINUITY_CHECK_FAILUREFET_TEST_FAILURERESISTANCE_OUT_OF_RANGE_FAILURESQUIB_PORT_DEPLOYEDSQUIB_PORT_FAILUREUNEXPECTED_SQUIB_CONNECTIONWINCH_CUTTER_DEPLOYEDWINCH_CUTTER_DEPLOY_FAILUREwinch_cutter_state_changed0x0010028AZIP_EXECUTIVE_V4_WINCH_CUTTER_IN_TERMINAL_STATEREEFING_CUTTER_DEPLOY_FAILUREPARACHUTE_DEPLOY_FAILUREPARACHUTE_DEPLOYEDZIP_EXECUTIVE_CODE_PARACHUTE_STATE_NOT_AVAILABLEZIP_EXECUTIVE_CODE_PARACHUTE_STATE_NOT_DISABLEDZIP_EXECUTIVE_CODE_PARACHUTE_STATE_FAILEDZIP_EXECUTIVE_CODE_PARACHUTE_STATE_UNHANDLEDZIP_EXECUTIVE_V4_PARACHUTE_STATE_NOT_DISABLEDZIP_EXECUTIVE_V4_PARACHUTE_STATE_FAILEDZIP_EXECUTIVE_V4_PARACHUTE_STATE_DEPLOY_FAILEDZIP_EXECUTIVE_V4_PARACHUTE_STATE_CUTTING_FAILEDZIP_EXECUTIVE_V4_PARACHUTE_STATE_SUCCESSZIP_EXECUTIVE_V4_PARACHUTE_STATE_DEPLOYINGZIP_EXECUTIVE_V4_PARACHUTE_STATE_NOT_AVAILABLEZIP_EXECUTIVE_V4_PARACHUTE_STATE_UNHANDLEDREEFING_CUTTER_CONTROL_FAILUREWINCH_CUTTER_CONTROL_FAILUREPARACHUTE_CONTROL_FAILURERESISTANCE_OUT_OF_RANGECRITICAL_WORKFLOW_ERROR
Likely outcomes — click to expand
Based on 1,040 missions where this alarm fired in the last
90 days
(for WINCH_CUTTER_DEPLOYED) as of 2026-10-13
Grounding vs discrepancy (of 2,377 ZERP issues filed on these missions)
Top work orders
- EV2: Inspect Aircraft after Droid Left Behind (DLB) · MAINTENANCE_ACTION 626
- Inspect Droid after Droid Left Behind (DLB) · MAINTENANCE_ACTION 428
- EV3: Inspect Aircraft after Droid Left Behind (DLB) · MAINTENANCE_ACTION 337
- Reset Droid after DLB · REPAIR 291
- V4 Zipping Point: Inspect Zipping Point after Droid Left Behind (DLB) - Ranger · MAINTENANCE_ACTION 157
Frequently replaced parts
| Part | P/N | Removals |
|---|---|---|
| ASSY, SPOOL AND LINE, DOCKING FIN, AIRCRAFT, P2 | 48477 | 1,201 |
| WINCH, ASSY, ZIP, P2 | 24078 | 304 |
| DOCKING FIN WINCH ASSY, ZIP, P2 | 24084 | 165 |
| PARALAND ASSY, DROID, P2 | 18427 | 126 |
| LEFT DOOR ASSY, DROID, P2 | 21830 | 105 |
Frequently co-occurring alarms (% of the 1,040 missions above)
Aggregated from fleet operations and refreshed daily. Individual outcomes may vary by site and configuration.
Applicable to all hardware versions
Background
Section titled “Background”Use this guide when a safety-system squib-control alarm, deployed state, or related CRITICAL_WORKFLOW_ERROR alarm report points to the Paraland, MGG, reefing cutter, winch cutter, distro, or squib driver.
We have generic alarms like CONTROL_FAILURE which are then paired with more specific information within the alarm reports of specific alarms such as RESISTANCE_OUT_OF_RANGE. Issues with the safety system are critical to root cause properly since this system ensures that our aircraft is able to safely deploy the parachute.
Troubleshooting Steps
Section titled “Troubleshooting Steps”graph TD
check-deploy-state-alarms{"<small><b>Step 1</b></small><br/>Question: Which deployment signal is present? I..."}
verify-winch-cutter-deployed["<small><b>Step 2</b></small><br/>Telemetry: Enter the mission identifier from the..."]
check-winch-cutter-deployment-signals{"<small><b>Step 3</b></small><br/>Question: Check the WINCH_CUTTER_DEPLOYED ala..."}
create-dlb-work-order["<small><b>Step 4</b></small><br/>Action: Create the DLB work order. For post-D..."]
failed-dlb-escalate-aircraft-structures{{"<small><b>Step 5</b></small><br/>Escalation: Escalate to Aircraft Structures & Me..."}}
escalate-safety-deploy-failure{{"<small><b>Step 6</b></small><br/>Escalation: WINCH_CUTTER_DEPLOY_FAILURE, REEFI..."}}
verify-chute-mgg-deployed["<small><b>Step 7</b></small><br/>Telemetry: Check the alarm report and mission te..."]
create-paraland-work-order["<small><b>Step 8</b></small><br/>Action: Create the Paraland work order. For p..."]
failed-paraland-escalate-aircraft-structures{{"<small><b>Step 9</b></small><br/>Escalation: Chute MGG deployment could not be con..."}}
check-driver-diagnostic-alarms{"<small><b>Step 10</b></small><br/>Question: Please inspect the Zerp alarm table, ..."}
escalate-powertrain-distro{{"<small><b>Step 11</b></small><br/>Escalation: Escalate to Powertrain On Call."}}
check-unexpected-squib-connection{"<small><b>Step 12</b></small><br/>Question: Is UNEXPECTED_SQUIB_CONNECTION active?"}
check-reefing-cutter-control{"<small><b>Step 13</b></small><br/>Question: Is REEFING_CUTTER_CONTROL_FAILURE a..."}
check-paraland-bom-004{"<small><b>Step 14</b></small><br/>Question: Is a -004 or earlier Paraland tube ..."}
upgrade-old-paraland-work-order["<small><b>Step 15</b></small><br/>Action: Create a work order to upgrade to a f..."]
reset-paraland-type-work-order["<small><b>Step 16</b></small><br/>Action: Create the Reset paraland type work o..."]
check-winch-cutter-control{"<small><b>Step 17</b></small><br/>Question: Is WINCH_CUTTER_CONTROL_FAILURE act..."}
check-winch-cutter-port-alarms{"<small><b>Step 18</b></small><br/>Question: Please inspect the alarm report of W..."}
inspect-replace-winch-cutter["<small><b>Step 19</b></small><br/>Action: Create the Inspect and Replace Winch ..."]
check-parachute-control{"<small><b>Step 20</b></small><br/>Question: Is PARACHUTE_CONTROL_FAILURE active?"}
check-parachute-port-alarms{"<small><b>Step 21</b></small><br/>Question: Please inspect the alarm report of P..."}
swap-paraland-fixed-wing-work-order["<small><b>Step 22</b></small><br/>Action: Create a work order to swap the paral..."]
check-auto-issue-report{"<small><b>Step 23</b></small><br/>Question: Is this an auto issue with CRITICAL_..."}
swap-paraland-work-order-auto["<small><b>Step 24</b></small><br/>Action: Create a work order to swap the paral..."]
escalate-firmware-safety{{"<small><b>Step 25</b></small><br/>Escalation: Escalate to P2 Firmware Safety On Call."}}
check-deploy-state-alarms -->|Winch cutter: WINCH_CUTTER...| verify-winch-cutter-deployed
check-deploy-state-alarms -->|PARACHUTE_DEPLOYED or PA...| verify-chute-mgg-deployed
check-deploy-state-alarms -->|WINCH_CUTTER_DEPLOY_FAILUR...| escalate-safety-deploy-failure
check-deploy-state-alarms -->|No, none of these alarms ar...| check-driver-diagnostic-alarms
verify-winch-cutter-deployed -->|Yes| create-dlb-work-order
verify-winch-cutter-deployed -->|No| check-winch-cutter-deployment-signals
check-winch-cutter-deployment-signals -->|Yes| create-dlb-work-order
check-winch-cutter-deployment-signals -->|No| failed-dlb-escalate-aircraft-structures
verify-chute-mgg-deployed -->|Yes, both states show deplo...| create-paraland-work-order
verify-chute-mgg-deployed -->|No, states conflict or are ...| failed-paraland-escalate-aircraft-structures
check-driver-diagnostic-alarms -->|Yes| escalate-powertrain-distro
check-driver-diagnostic-alarms -->|No| check-unexpected-squib-connection
check-unexpected-squib-connection -->|Yes| check-paraland-bom-004
check-unexpected-squib-connection -->|No| check-reefing-cutter-control
check-reefing-cutter-control -->|Yes| check-paraland-bom-004
check-reefing-cutter-control -->|No| check-winch-cutter-control
check-paraland-bom-004 -->|Yes| upgrade-old-paraland-work-order
check-paraland-bom-004 -->|No| reset-paraland-type-work-order
upgrade-old-paraland-work-order --> check-winch-cutter-control
reset-paraland-type-work-order --> check-winch-cutter-control
check-winch-cutter-control -->|Yes| check-winch-cutter-port-alarms
check-winch-cutter-control -->|No| check-parachute-control
check-winch-cutter-port-alarms -->|Yes| inspect-replace-winch-cutter
check-winch-cutter-port-alarms -->|No| escalate-firmware-safety
inspect-replace-winch-cutter --> check-parachute-control
check-parachute-control -->|Yes| check-parachute-port-alarms
check-parachute-control -->|No| check-auto-issue-report
check-parachute-port-alarms -->|Yes| swap-paraland-fixed-wing-work-order
check-parachute-port-alarms -->|No| escalate-firmware-safety
check-auto-issue-report -->|Yes| swap-paraland-work-order-auto
check-auto-issue-report -->|No| escalate-firmware-safety
style check-deploy-state-alarms fill:#dbeafe,stroke:#3b82f6,color:#1e3a5f
style check-winch-cutter-deployment-signals fill:#dbeafe,stroke:#3b82f6,color:#1e3a5f
style create-dlb-work-order fill:#dcfce7,stroke:#22c55e,color:#14532d
style failed-dlb-escalate-aircraft-structures fill:#fef3c7,stroke:#f59e0b,color:#78350f
style escalate-safety-deploy-failure fill:#fef3c7,stroke:#f59e0b,color:#78350f
style create-paraland-work-order fill:#dcfce7,stroke:#22c55e,color:#14532d
style failed-paraland-escalate-aircraft-structures fill:#fef3c7,stroke:#f59e0b,color:#78350f
style check-driver-diagnostic-alarms fill:#dbeafe,stroke:#3b82f6,color:#1e3a5f
style escalate-powertrain-distro fill:#fef3c7,stroke:#f59e0b,color:#78350f
style check-unexpected-squib-connection fill:#dbeafe,stroke:#3b82f6,color:#1e3a5f
style check-reefing-cutter-control fill:#dbeafe,stroke:#3b82f6,color:#1e3a5f
style check-paraland-bom-004 fill:#dbeafe,stroke:#3b82f6,color:#1e3a5f
style upgrade-old-paraland-work-order fill:#dcfce7,stroke:#22c55e,color:#14532d
style reset-paraland-type-work-order fill:#dcfce7,stroke:#22c55e,color:#14532d
style check-winch-cutter-control fill:#dbeafe,stroke:#3b82f6,color:#1e3a5f
style check-winch-cutter-port-alarms fill:#dbeafe,stroke:#3b82f6,color:#1e3a5f
style inspect-replace-winch-cutter fill:#dcfce7,stroke:#22c55e,color:#14532d
style check-parachute-control fill:#dbeafe,stroke:#3b82f6,color:#1e3a5f
style check-parachute-port-alarms fill:#dbeafe,stroke:#3b82f6,color:#1e3a5f
style swap-paraland-fixed-wing-work-order fill:#dcfce7,stroke:#22c55e,color:#14532d
style check-auto-issue-report fill:#dbeafe,stroke:#3b82f6,color:#1e3a5f
style swap-paraland-work-order-auto fill:#dcfce7,stroke:#22c55e,color:#14532d
style escalate-firmware-safety fill:#fef3c7,stroke:#f59e0b,color:#78350f Hover or focus a block to preview it. Select the block to keep the preview open.
1 question
Which deployment signal is present? If
winch_cutter_state_changed or ZIP_EXECUTIVE_V4_WINCH_CUTTER_IN_TERMINAL_STATE (0x0010028A) is the grounding signal, check the reported new state: it can indicate deployment or deploy failure. 2 telemetry
Enter the mission identifier from the alarm report. Check the mission's squib alarm report at or after the cutter event.
Enter the mission identifier above to load the mission in Baraza.
Does SQUIB_PORT_DEPLOYED name WINCH_CUTTER for this mission?
3 question
Check the
WINCH_CUTTER_DEPLOYED alarm and the winch_cutter_state_changed event for this mission. The event's new state must be WINCH_CUTTER_STATE_DEPLOYED.Do both report cutter deployment?
4 action
Create the DLB work order. For post-DLB work, use the applicable UMM: EV2 — 5.5.1.e Reset Zip After Droid Left Behind or EV3 — Service Aircraft after Droid Left Behind.
5 escalation
Escalate to Aircraft Structures & Mechanisms On Call.
6 escalation
WINCH_CUTTER_DEPLOY_FAILURE, REEFING_CUTTER_DEPLOY_FAILURE, and PARACHUTE_DEPLOY_FAILURE trigger when the safety control system has attempted to deploy part of the safety system, but detected an anomaly with the deployment sequence. A reported WINCH_CUTTER_STATE_DEPLOY_FAILED state change follows this same escalation path. As a result, the system is not certain whether the commanded deployment completed correctly.These alarms block further deliveries or flights until resolved. They generally latch even if the failure condition is resolved, unless the aircraft is power cycled. This ensures temporary failures are investigated and verified before the aircraft is allowed back in service.
This condition is expected to be extremely rare and should always be escalated to P2 Firmware Safety on Call. Escalate to P2 Firmware Safety On Call.
7 telemetry
Check the alarm report and mission telemetry at the parachute event:
- Confirm
PARACHUTE_DEPLOYEDorparachute_state=SUCCESS. - Confirm
squib_chute_port_statereachesDEPLOYEDfor the same event. - Inspect
resistance_port0in the embeddedDistro A Squib Resistanceplot. It may read 0 after deployment. IfSQUIB_PORT_DEPLOYEDappears, verify the alarm report names the parachute squib.
resistance_port0 is physical port 0 on EV2 and EV3. Select Yes only when both the parachute state and squib-port state show deployment. If either is missing or conflicts, select No and escalate. The resistance trace and SQUIB_PORT_DEPLOYED are supporting signals. Enter the mission identifier above to load the plot.
Do both the parachute state and squib-chute port state show deployment?
8 action
Create the Paraland work order. For post-paraland work, see UMM: 5.5.1.a Zip Post-Incident Inspection.
9 escalation
Chute MGG deployment could not be confirmed from the reported state and available telemetry. Escalate to Aircraft Structures & Mechanisms On Call. Missing continuity or resistance failure alarms after a deployment do not establish a failed paraland.
10 question
Please inspect the Zerp alarm table, as well as the alarm report of the
Are any of these SquibControlAlarm values active?
-
-
-
-
-
-
-
-
-
-
-
-
-
-
CONTROL_FAILURE (if present).Are any of these SquibControlAlarm values active?
-
COMMUNICATION_FAILURE-
TIMED_OUT_WAITING_FOR_POWER_FAILURE-
DRIVER_UNEXPECTED_SYSTEM_STATE_FAILURE-
DRIVER_UNEXPECTED_FEN_STATE_FAILURE-
BACKUP_POWER_FAILURE-
DRIVER_FAULT_STATUS_BIT_ASSERTED-
DRIVER_POWER_FAILURE-
DRIVER_CLOCK_FAILURE-
DRIVER_OTP_CRC_FAILURE-
DIAGNOSTIC_TEST_FAILURE-
DIAGNOSTIC_TEST_TIMEOUT_FAILURE-
VRCM_TEST_FAILURE-
SHORT_BETWEEN_LOOPS_TEST_FAILURE-
FET_TEST_FAILURE 11 escalation
Escalate to Powertrain On Call.
12 question
Is
UNEXPECTED_SQUIB_CONNECTION active? 13 question
Is
REEFING_CUTTER_CONTROL_FAILURE active? 14 question
Is a
-004 or earlier Paraland tube installed? 15 action
Create a work order to upgrade to a fixed wing capable paraland:
1. Remove the
2. Install the fixed wing capable paraland. For steps, see UMM: 90.1.1.d Install Paraland Tube.
3. Scrap the removed paraland tube.
1. Remove the
-004 paraland. For steps, see UMM: 90.1.1.c Remove Paraland Tube.2. Install the fixed wing capable paraland. For steps, see UMM: 90.1.1.d Install Paraland Tube.
3. Scrap the removed paraland tube.
16 action
Create the Reset paraland type work order. For steps, see UMM: 90.1.1.e Perform Set Paraland Type Configuration.
17 question
Is
WINCH_CUTTER_CONTROL_FAILURE active? 18 question
Please inspect the alarm report of
Are
WINCH_CUTTER_CONTROL_FAILURE as well as the validator results.Are
LEAKAGE_TEST_FAILURE, CONTINUITY_CHECK_FAILURE, or RESISTANCE_OUT_OF_RANGE_FAILURE present or does the validator mention a "Winch cutter control failure"? 19 action
Create the Inspect and Replace Winch Cutter work order:
1. Remove the winch cutter. For steps, see UMM: 32.3.5.b Remove Winch Line Cutter.
2. Return the winch cutter to P2 Droid On Call.
3. Install the new winch line cutter. For steps, see UMM: 32.3.5.c Install Winch Line Cutter.
1. Remove the winch cutter. For steps, see UMM: 32.3.5.b Remove Winch Line Cutter.
2. Return the winch cutter to P2 Droid On Call.
3. Install the new winch line cutter. For steps, see UMM: 32.3.5.c Install Winch Line Cutter.
20 question
Is
PARACHUTE_CONTROL_FAILURE active? 21 question
Please inspect the alarm report of
Are
PARACHUTE_CONTROL_FAILURE as well as the validator results.Are
LEAKAGE_TEST_FAILURE, CONTINUITY_CHECK_FAILURE, or RESISTANCE_OUT_OF_RANGE_FAILURE present or does the validator mention a "Parachute control failure"? 22 action
Create a work order to swap the paraland:
1. Remove the existing paraland tube. For steps, see UMM: 90.1.1.c Remove Paraland Tube.
2. Install the fixed wing capable paraland. For steps, see UMM: 90.1.1.d Install Paraland Tube.
3. Transfer the removed paraland tube to MX holding and open a discrepancy against the removed paraland for
1. Remove the existing paraland tube. For steps, see UMM: 90.1.1.c Remove Paraland Tube.
2. Install the fixed wing capable paraland. For steps, see UMM: 90.1.1.d Install Paraland Tube.
3. Transfer the removed paraland tube to MX holding and open a discrepancy against the removed paraland for
wire harness resistance issue present, swap MGG harness to resolve. 23 question
Is this an auto issue with
CRITICAL_WORKFLOW_ERROR and squib_resistance/chute_mgg present? 24 action
Create a work order to swap the paraland:
1. Remove the existing paraland tube. For steps, see UMM: 90.1.1.c Remove Paraland Tube.
2. Install the fixed wing capable paraland. For steps, see UMM: 90.1.1.d Install Paraland Tube.
3. Transfer the removed paraland tube to MX holding and open a discrepancy against the removed paraland for
1. Remove the existing paraland tube. For steps, see UMM: 90.1.1.c Remove Paraland Tube.
2. Install the fixed wing capable paraland. For steps, see UMM: 90.1.1.d Install Paraland Tube.
3. Transfer the removed paraland tube to MX holding and open a discrepancy against the removed paraland for
wire harness resistance issue present, swap MGG harness to resolve. 25 escalation
Escalate to P2 Firmware Safety On Call.
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.
SquibControlAlarm Reference
Section titled “SquibControlAlarm Reference”| Value | Meaning |
|---|---|
CONTROL_FAILURE |
The squib subsystem is unhealthy and cannot be trusted. |
COMMUNICATION_FAILURE |
Cannot communicate with the squib driver IC. |
TIMED_OUT_WAITING_FOR_POWER_FAILURE |
Timed out waiting for power to be ready. |
DRIVER_UNEXPECTED_SYSTEM_STATE_FAILURE |
The squib driver reports unexpected system state. |
DRIVER_UNEXPECTED_FEN_STATE_FAILURE |
The squib driver reports unexpected arming inputs, also known as FET Enable pins, state. |
BACKUP_POWER_FAILURE |
Backup power or supercap failure. |
DRIVER_FAULT_STATUS_BIT_ASSERTED |
The squib driver reports fault status bit asserted. |
DRIVER_POWER_FAILURE |
The squib driver reports power failure. |
DRIVER_CLOCK_FAILURE |
The squib driver reports clock failure. |
DRIVER_OTP_CRC_FAILURE |
The squib driver reports OTP CRC failure. |
DIAGNOSTIC_TEST_FAILURE |
Diagnostic test failed for any reason. |
DIAGNOSTIC_TEST_TIMEOUT_FAILURE |
Diagnostic test is taking too long. |
VRCM_TEST_FAILURE |
Voltage Regulator Current Monitor test failure. |
LEAKAGE_TEST_FAILURE |
Leakage test failure. |
SHORT_BETWEEN_LOOPS_TEST_FAILURE |
The test for short between loops failed. |
CONTINUITY_CHECK_FAILURE |
Resistance on a squib channel is above 200 Ohm. |
FET_TEST_FAILURE |
FET test failure. |
RESISTANCE_OUT_OF_RANGE_FAILURE |
Measured resistance is out of range. Current firmware uses SQUIB_PORT_DEPLOYED instead when the port is marked deployed. |
SQUIB_PORT_DEPLOYED |
Post-deployment continuity or resistance diagnostics indicate a port marked deployed; the alarm report names the squib channel. |
SQUIB_PORT_FAILURE |
There is a fault on at least one of the squib ports. |
UNEXPECTED_SQUIB_CONNECTION |
SPI failure during diagnostic setup or results. |
Did this guide help you get unblocked?