SIDE_B_MISSED_COOPERATIVE_AIRCRAFT
Viewing this guide for
Applicable alarms (1)
SIDE_B_MISSED_COOPERATIVE_AIRCRAFT
Likely outcomes — click to expand
Based on 82 missions where this alarm fired in the last 90 days as of 2026-10-13
Grounding vs discrepancy (of 3 ZERP issues filed on these missions)
Frequently replaced parts
| Part | P/N | Removals |
|---|---|---|
| FLIGHT COMPUTER ASSY, ZIP, P2 | 20994 | 8 |
Frequently co-occurring alarms (% of the 82 missions above)
Aggregated from fleet operations and refreshed daily. Individual outcomes may vary by site and configuration.
Background
Section titled “Background”This is a DAA related detection performance alarm. The DAA Tracker uses the detections from the ADSB devices in each compute. This alarm gets activated when the ADSB device in compute B does not get position detections that compute A sees during a minute of flight (or data streaming when docked) inside of the safety puck 5 km radius laterally and 2.5 km half height. This indicates degradation in either the device or the antennas. Compute B is considered the secondary source of detections.
During preflight it will block launch; during flight it will command a DockAsap so the cooperative DAA system avoids working with degraded hardware.
Troubleshooting Steps
Section titled “Troubleshooting Steps”graph TD
does-this-alarm-occur-during-preflight{"<small><b>Step 1</b></small><br/>Question: Does this alarm occur during prefligh..."}
preflight-wait-for-two-2-minutes["<small><b>Step 2</b></small><br/>Action: Wait for two 2 minutes."]
preflight-has-the-alarm-cleared{"<small><b>Step 3</b></small><br/>Question: Has the alarm cleared?"}
preflight-yes-aircraft-may-return-to-se("<small><b>Step 4</b></small><br/>Reference: The Aircraft may return to service.")
check-the-alarm-report-is-the-missed-ai{"<small><b>Step 5</b></small><br/>Question: Check the alarm report. Is the missed..."}
yes-wait-until-the-aircraft-has-left-the["<small><b>Step 6</b></small><br/>Action: Wait until the Aircraft has left the ..."]
no-continue-with-the-next-step-preflight["<small><b>Step 7</b></small><br/>Action: Continue with the next step."]
preflight-no-wait-for-two-2-minutes["<small><b>Step 8</b></small><br/>Action: Wait for two 2 minutes."]
preflight-no-has-the-alarm-cleared{"<small><b>Step 9</b></small><br/>Question: Has the alarm cleared?"}
preflight-no-yes-aircraft-may-return("<small><b>Step 10</b></small><br/>Reference: The Aircraft may return to service.")
preflight-no-no-power-cycle-the-aircraf{"<small><b>Step 11</b></small><br/>Question: Power cycle the Aircraft. See Power ..."}
preflight-power-cycle-yes-return("<small><b>Step 12</b></small><br/>Reference: The Aircraft may return to service.")
preflight-power-cycle-no-escalate{{"<small><b>Step 13</b></small><br/>Escalation: Escalate to P2 Zip DAA Tracker On Call."}}
flight-did-alarm-clear-during-the-retur{"<small><b>Step 14</b></small><br/>Question: Did alarm clear during the return fli..."}
flight-yes-continue-to-the-next-step["<small><b>Step 15</b></small><br/>Action: Continue to the next step."]
flight-no-power-cycle-the-aircraft["<small><b>Step 16</b></small><br/>Action: Power cycle the Aircraft. See Power ..."]
flight-no-did-the-alarm-clear{"<small><b>Step 17</b></small><br/>Question: Did the alarm clear?"}
flight-no-yes-continue-to-the-next-step["<small><b>Step 18</b></small><br/>Action: Continue to the next step."]
flight-no-no-escalate-to-daa-tracker{{"<small><b>Step 19</b></small><br/>Escalation: Escalate to P2 Zip DAA Tracker On Call."}}
is-this-the-first-occurrence-of-the-ala{"<small><b>Step 20</b></small><br/>Question: Is this the first occurrence of the a..."}
first-occurrence-yes-check-detections{"<small><b>Step 21</b></small><br/>Question: In the alarm report Aircraft/Droid ..."}
detections-eq-zero-disposition["<small><b>Step 22</b></small><br/>Action: sum_total_detections_compute_b == ..."]
detections-gt-zero-disposition["<small><b>Step 23</b></small><br/>Action: sum_total_detections_compute_b 0..."]
first-occurrence-no-commercial-ops["<small><b>Step 24</b></small><br/>Action: **Commercial Operations**: 1. Contact..."]
does-this-alarm-occur-during-preflight -->|Preflight| preflight-wait-for-two-2-minutes
does-this-alarm-occur-during-preflight -->|Flight| flight-did-alarm-clear-during-the-retur
preflight-wait-for-two-2-minutes --> preflight-has-the-alarm-cleared
preflight-has-the-alarm-cleared -->|Yes| preflight-yes-aircraft-may-return-to-se
preflight-has-the-alarm-cleared -->|No| check-the-alarm-report-is-the-missed-ai
check-the-alarm-report-is-the-missed-ai -->|YES| yes-wait-until-the-aircraft-has-left-the
check-the-alarm-report-is-the-missed-ai -->|NO| no-continue-with-the-next-step-preflight
yes-wait-until-the-aircraft-has-left-the --> preflight-no-wait-for-two-2-minutes
no-continue-with-the-next-step-preflight --> preflight-no-wait-for-two-2-minutes
preflight-no-wait-for-two-2-minutes --> preflight-no-has-the-alarm-cleared
preflight-no-has-the-alarm-cleared -->|YES| preflight-no-yes-aircraft-may-return
preflight-no-has-the-alarm-cleared -->|NO| preflight-no-no-power-cycle-the-aircraf
preflight-no-no-power-cycle-the-aircraf -->|YES| preflight-power-cycle-yes-return
preflight-no-no-power-cycle-the-aircraf -->|NO| preflight-power-cycle-no-escalate
flight-did-alarm-clear-during-the-retur -->|Yes| flight-yes-continue-to-the-next-step
flight-did-alarm-clear-during-the-retur -->|No| flight-no-power-cycle-the-aircraft
flight-yes-continue-to-the-next-step --> is-this-the-first-occurrence-of-the-ala
flight-no-power-cycle-the-aircraft --> flight-no-did-the-alarm-clear
flight-no-did-the-alarm-clear -->|YES| flight-no-yes-continue-to-the-next-step
flight-no-did-the-alarm-clear -->|NO| flight-no-no-escalate-to-daa-tracker
flight-no-yes-continue-to-the-next-step --> is-this-the-first-occurrence-of-the-ala
is-this-the-first-occurrence-of-the-ala -->|Yes| first-occurrence-yes-check-detections
is-this-the-first-occurrence-of-the-ala -->|No| first-occurrence-no-commercial-ops
first-occurrence-yes-check-detections -->|sum_total_detections_compu...| detections-eq-zero-disposition
first-occurrence-yes-check-detections -->|sum_total_detections_compu...| detections-gt-zero-disposition
style does-this-alarm-occur-during-preflight fill:#dbeafe,stroke:#3b82f6,color:#1e3a5f
style preflight-wait-for-two-2-minutes fill:#dcfce7,stroke:#22c55e,color:#14532d
style preflight-has-the-alarm-cleared fill:#dbeafe,stroke:#3b82f6,color:#1e3a5f
style preflight-yes-aircraft-may-return-to-se fill:#f3e8ff,stroke:#a855f7,color:#581c87
style check-the-alarm-report-is-the-missed-ai fill:#dbeafe,stroke:#3b82f6,color:#1e3a5f
style yes-wait-until-the-aircraft-has-left-the fill:#dcfce7,stroke:#22c55e,color:#14532d
style no-continue-with-the-next-step-preflight fill:#dcfce7,stroke:#22c55e,color:#14532d
style preflight-no-wait-for-two-2-minutes fill:#dcfce7,stroke:#22c55e,color:#14532d
style preflight-no-has-the-alarm-cleared fill:#dbeafe,stroke:#3b82f6,color:#1e3a5f
style preflight-no-yes-aircraft-may-return fill:#f3e8ff,stroke:#a855f7,color:#581c87
style preflight-no-no-power-cycle-the-aircraf fill:#dbeafe,stroke:#3b82f6,color:#1e3a5f
style preflight-power-cycle-yes-return fill:#f3e8ff,stroke:#a855f7,color:#581c87
style preflight-power-cycle-no-escalate fill:#fef3c7,stroke:#f59e0b,color:#78350f
style flight-did-alarm-clear-during-the-retur fill:#dbeafe,stroke:#3b82f6,color:#1e3a5f
style flight-yes-continue-to-the-next-step fill:#dcfce7,stroke:#22c55e,color:#14532d
style flight-no-power-cycle-the-aircraft fill:#dcfce7,stroke:#22c55e,color:#14532d
style flight-no-did-the-alarm-clear fill:#dbeafe,stroke:#3b82f6,color:#1e3a5f
style flight-no-yes-continue-to-the-next-step fill:#dcfce7,stroke:#22c55e,color:#14532d
style flight-no-no-escalate-to-daa-tracker fill:#fef3c7,stroke:#f59e0b,color:#78350f
style is-this-the-first-occurrence-of-the-ala fill:#dbeafe,stroke:#3b82f6,color:#1e3a5f
style first-occurrence-yes-check-detections fill:#dbeafe,stroke:#3b82f6,color:#1e3a5f
style detections-eq-zero-disposition fill:#dcfce7,stroke:#22c55e,color:#14532d
style detections-gt-zero-disposition fill:#dcfce7,stroke:#22c55e,color:#14532d
style first-occurrence-no-commercial-ops fill:#dcfce7,stroke:#22c55e,color:#14532d Hover or focus a block to preview it. Select the block to keep the preview open.
1 question
Does this alarm occur during preflight or flight?
2 action
Wait for two (2) minutes.
3 question
Has the alarm cleared?
4 reference
The Aircraft may return to service.
5 question
Check the alarm report. Is the missed Aircraft ICAO (transform it from integer to hex) still in the vicinity in the Fleet View?
6 action
Wait until the Aircraft has left the vicinity and then continue with the next step.
7 action
Continue with the next step.
8 action
Wait for two (2) minutes.
9 question
Has the alarm cleared?
10 reference
The Aircraft may return to service.
11 question
Power cycle the Aircraft. See Power Cycle Aircraft. Has the alarm cleared?
12 reference
The Aircraft may return to service.
13 escalation
Escalate to P2 Zip DAA Tracker On Call.
14 question
Did alarm clear during the return flight?
15 action
Continue to the next step.
16 action
Power cycle the Aircraft. See Power Cycle Aircraft.
17 question
Did the alarm clear?
18 action
Continue to the next step.
19 escalation
Escalate to P2 Zip DAA Tracker On Call.
20 question
Is this the first occurrence of the alarm for this Aircraft in the past 24 hours?
21 question
In the alarm report (Aircraft/Droid Alarm Report), is
sum_total_detections_compute_b set to ==0 or >0? 22 action
sum_total_detections_compute_b == 0:- Commercial Operations: The Aircraft can return to service. The alarm is likely to reoccur in subsequent flights.
- Test Operations not relying on ADS-B DAA: The Aircraft may return to service. DAA is not assumed to add safety.
23 action
sum_total_detections_compute_b > 0:- Commercial Operations: The Aircraft may return to service. Note a possible reduction in safety.
- Test Operations not relying on ADS-B DAA: The Aircraft may return to service. DAA is not assumed to add safety.
24 action
Commercial Operations:
1. Contact p2-avionics-on-call and ask them to run the diagnostic script to determine whether this is a compute fault or degraded aircraft performance.
2. Was a sign-off to resume operations given, or was the instruction to change the compute assembly?
- Resume operation: The Aircraft can return to service.
- Replace compute board: Replace the compute board and then the Aircraft may return to service.
- UMM: Remove Flight Compute Assembly
- UMM: Install Flight Compute Assembly
Test Operations not relying on ADS-B DAA: The Aircraft may return to service. DAA is not assumed to add safety.
1. Contact p2-avionics-on-call and ask them to run the diagnostic script to determine whether this is a compute fault or degraded aircraft performance.
2. Was a sign-off to resume operations given, or was the instruction to change the compute assembly?
- Resume operation: The Aircraft can return to service.
- Replace compute board: Replace the compute board and then the Aircraft may return to service.
- UMM: Remove Flight Compute Assembly
- UMM: Install Flight Compute Assembly
Test Operations not relying on ADS-B DAA: The Aircraft may return to service. DAA is not assumed to add safety.
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.