| Recurring |
one_organization |
(a) The software failure incident related to the failure of cabin altitude pressure switches on Boeing 737 series airplanes has happened again within the same organization, Boeing. The article mentions that an operator reported that both pressure switches had failed on-wing functional tests on three different 737 models in September [116427]. This indicates a recurring issue with the pressure switches within Boeing's aircraft.
(b) The software failure incident related to the failure of cabin altitude pressure switches on Boeing 737 series airplanes has not been explicitly mentioned to have occurred at multiple organizations in the provided article. |
| Phase (Design/Operation) |
design, operation |
(a) The software failure incident related to the design phase is evident in the article. The Federal Aviation Administration issued a directive to address possible failures of cabin altitude pressure switches on Boeing 737 series airplanes. The failure of these switches could result in the cabin altitude warning system not activating when the cabin moves past 10,000ft, leading to dangerously low oxygen levels. This issue was identified after an operator reported that both pressure switches had failed on-wing functional tests on three different 737 models in September. Boeing initially reviewed the issue, including the expected failure rate of the switches, and found it did not pose a safety issue. However, subsequent investigation and analysis revealed that the failure rate of both switches was much higher than initially estimated, indicating a design failure in the system [116427].
(b) The software failure incident related to the operation phase is also highlighted in the article. The Federal Aviation Administration mandated all Boeing 737 airplanes to utilize two cabin altitude pressure switches to provide redundancy in case of one switch's failure. The directive required operators to conduct repetitive tests of the switches and replace them if needed. The FAA also specified that tests must be conducted within a certain timeframe or flight hours to ensure the proper operation of the cabin altitude pressure switches. This indicates that the failure incident was also influenced by factors related to the operation or maintenance of the system [116427]. |
| Boundary (Internal/External) |
within_system |
(a) within_system: The software failure incident related to the cabin altitude pressure switches on Boeing 737 airplanes was within the system. The failure of the pressure switches could result in the cabin altitude warning system not activating when the cabin moves past 10,000ft, leading to dangerously low oxygen levels. The FAA directive mandated inspections and replacements of the switches due to a much higher failure rate than initially estimated, indicating an internal system issue [116427].
(b) outside_system: There is no information in the articles suggesting that the software failure incident related to the cabin altitude pressure switches on Boeing 737 airplanes was due to contributing factors originating from outside the system. |
| Nature (Human/Non-human) |
non-human_actions |
(a) The software failure incident occurring due to non-human actions:
- The article reports that the Federal Aviation Administration issued a directive to address possible failures of cabin altitude pressure switches on Boeing 737 series airplanes [116427].
- The failure of the switches could result in the cabin altitude warning system not activating when the cabin moves past 10,000ft, which could lead to dangerously low oxygen levels [116427].
- Boeing initially reviewed the issue and found that the expected failure rate of the switches did not pose a safety issue. However, subsequent investigation revealed that the failure rate of both switches was much higher than initially estimated, indicating a safety issue [116427].
- The FAA mentioned that it does not yet have sufficient information to determine the cause of the unexpectedly high failure rate of the switches [116427].
(b) The software failure incident occurring due to human actions:
- The article does not specifically mention any human actions contributing to the software failure incident. |
| Dimension (Hardware/Software) |
hardware |
(a) The software failure incident occurring due to hardware:
- The article mentions that the Federal Aviation Administration issued a directive to address possible failures of cabin altitude pressure switches on Boeing 737 series airplanes [116427].
- The failure of the pressure switches could result in the cabin altitude warning system not activating when the cabin moves past 10,000ft, which is a critical safety concern as oxygen levels become dangerously low at higher altitudes [116427].
- Boeing initially reviewed the issue, including the expected failure rate of the switches, and found it did not pose a safety issue. However, subsequent investigation and analysis revealed that the failure rate of both switches was much higher than initially estimated, leading to safety concerns [116427].
(b) The software failure incident occurring due to software:
- The article does not specifically mention any software-related contributing factors that originated in software for the failure of the cabin altitude pressure switches on Boeing 737 series airplanes [116427].
- The focus of the article is primarily on the hardware aspect of the pressure switches and the safety implications of their failure, rather than on any software-related issues leading to the failure incident [116427].
Therefore, based on the information provided in the article, the software failure incident is primarily attributed to hardware-related factors rather than software-related factors. |
| Objective (Malicious/Non-malicious) |
non-malicious |
(a) The software failure incident related to the cabin altitude pressure switches on Boeing 737 airplanes was non-malicious. The failure was due to a high failure rate of the switches, which was initially underestimated by Boeing and later determined to pose a safety issue by the FAA. The failure of the switches could result in the cabin altitude warning system not activating when needed, potentially leading to dangerous situations for cabin crew and pilots [116427]. |
| Intent (Poor/Accidental Decisions) |
unknown |
The software failure incident related to the cabin altitude pressure switches on Boeing 737 airplanes was not directly attributed to poor decisions or accidental decisions. The failure was primarily due to the unexpected high failure rate of the switches, which was initially underestimated by Boeing and the FAA. The incident led to the directive for inspections and replacements to address the safety issue of the switches not activating the cabin altitude warning system when oxygen levels become dangerously low [116427]. |
| Capability (Incompetence/Accidental) |
development_incompetence |
(a) The software failure incident related to development incompetence is evident in the article as Boeing initially reviewed the issue, including the expected failure rate of the cabin altitude pressure switches, and found that it did not pose a safety issue. However, subsequent investigation and analysis revealed that the failure rate of both switches was much higher than initially estimated, indicating a lack of accurate assessment or understanding of the potential risks involved [116427].
(b) The software failure incident related to accidental factors is highlighted in the article when it mentions that the FAA stated it does not yet have sufficient information to determine what caused the unexpectedly high failure rate of the cabin altitude pressure switches. This lack of understanding or knowledge about the root cause of the issue points to accidental factors contributing to the software failure incident [116427]. |
| Duration |
temporary |
The software failure incident related to the cabin altitude pressure switches on Boeing 737 airplanes can be categorized as a temporary failure. The failure of the switches was initially believed not to pose a safety issue by Boeing, but subsequent investigation and analysis revealed that the failure rate was much higher than initially estimated, leading to the determination that it does pose a safety issue [116427]. This indicates that the failure was temporary in nature, as it was not immediately recognized as a significant problem but was later identified as a safety issue after further investigation. |
| Behaviour |
crash, omission, value, other |
(a) crash: The software failure incident in this case can be categorized as a crash. The failure of the cabin altitude pressure switches could result in the cabin altitude warning system not activating when the cabin moves past 10,000ft, potentially leading to dangerously low oxygen levels and incapacitating cabin crew and pilots [116427].
(b) omission: The software failure incident can also be categorized as an omission. The failure of the pressure switches to activate the cabin altitude warning system at the appropriate altitude can be seen as an omission of performing its intended function [116427].
(c) timing: The timing of the software failure incident is not explicitly mentioned in the articles.
(d) value: The software failure incident can be categorized as a value failure. The failure of the switches results in the altitude warning system not activating correctly when oxygen levels become dangerously low in the cabin, indicating an incorrect performance of the intended function [116427].
(e) byzantine: The software failure incident does not exhibit characteristics of a byzantine failure.
(f) other: The software failure incident can be categorized as a failure due to a system losing state and not performing any of its intended functions (a crash) and also as a failure due to the system performing its intended functions incorrectly (value). |