Originally Posted by
Old Ag
The warnings were unrelated to an actual pressurization problem. The warning was an "Auto Fail" warning with an "ALTN" annunciation light. This means there was an error in the primary pressurization controller that the alternate pressure controller did not experience, so control of the pressurization automatically switched to the alternate controller (there are two controllers that operate simultaneously with one active and and one operating as an alternate controller in a stand by mode). Every flight they automatically alternate primary and alternate roles. So
in each case, the issue was resolved by the controllers automatically switching roles and throwing the warning. The NTSB has also discounted the Auto Fail being related to the loss of the plug. One more point, on the Jan 4th flight, the light came on after landing, further discrediting an actual pressurization issue.
Here is just one of the articles on the NTBS's statement on the topic:
https://www.webcenterfairbanks.com/2...outputType=amp
Bottom line is the histrionics about the "warning lights" should be discounted and the "warning lights" can't be used as evidence that the WiFi installation was related to the event. It doesn't mean the WiFi installation was not related to the event, it is just that the pressurization system warnings do not support that theory.
Respectfully, I think you are over-reaching with what is known. On the 8th the NTSB
had not yet established a correlation and this article is just parroting the same news conference we all watched, one hour later. NTSB clearly said they are still investigating. I don't believe anybody from the investigation ruled out a correlation, they just said they had not established a correlation after 2 days of looking (at mostly other things).
"The NTSB will go back and look at cabin pressure data from the flight data recorder to decipher what caused the de-pressurization, as well as seek the expertise of a pressure control system specialist from Boeing."
Furthermore, your statement that "the issue was resolved by the controllers automatically switching" is demonstrably false because "the issue" returned after the first switchover. The fact that the ALTN system didn't flag tells us less than you think, especially for an intermittent problem. In fact the aircraft was restricted from ETOPS because from Alaska Airlines' perspective the issue had not been resolved. Whether or not it was correlated to the incident remains to be seen. Definitely not "histrionics" to leave it on the table at this point.