ECAM 警告是 FWS 提供的，而如果两部 FWS 故障了，CDS 可以提供一个 FWS FWS 1+2 FAULT 的警告，基本上就是让机组保持监控 SD 页面和顶板，并注明一些不可用的功能。
2部 FWS 安装在 CPIOM J1 上：
而如果同时还有其他 CPIOM 故障，则 CDS 会提供 FWS FWS 1+2 & CPIOM FAULT 警告。由于 CDS 仅能显示固定的页面，无法根据具体故障灵活排版。
如上图所示，这个警告的每一行对应一个 CPIOM 故障会出现的内容，而如果某个 CPIOM 没有故障，则相应行不显示内容，空出来。我的疑问是，题图是所有 CPIOM 都故障的示意，然而仍然有一行是空出来的（红框所示）。
空客的回复中是这样解释的：失去两部 FWS 有两种可能，一是 CPIOM 软件故障了，二是为其供电的 DC EMER 1 bus bar 和 DC 2 bus bar 故障了。而如果是供电故障，则那一行会有显示。
具体请参考 TechRequest 原文：
Q: FWS FWS 1+2 & CPIOM FAULT
As the note:
Each line of text of the procedure is assigned to an action or information that results from the failure of a specific CPIOM. "The following illustration illustrates the entire alert display, in the case of the failure of CPIOM group J1 combined with all other CPIOM groups."
Why there's still a line gap?
A:
The FWS FWS 1+2 & CPIOM FAULT ECAM alert is displayed when both FWS and CPIOM are faulty.
The title of this alert is associated with the Flight Warning System (FWS) but this alert is fully managed and displayed by the Control and Display System (CDS).
The loss of both FWS may be due to the:
- Loss of CPIOM J11 and J12, which respectively host the FWS 1 and the FWS 2, or
- Loss of DC EMER 1 bus bar and DC 2 bus bar, which respectively supply the CPIOM J11 and the CPIOM J12.
Due to the loss of both FWS and/or the loss of bus bars, the CDS has a limited capability to manage the order of ECAM lines. Therefore, this blank line within this alert is a normal behavior of the CDS.
If the loss of both FWS is due to the loss of bus bars, another ECAM alert will be displayed and the blank line you indicated will be filled by procedure lines.