B747-400 VNAV PTH Descent Speed
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Thanks for the reply. I agree that it would probably be a rare day where VNAV accelerates even close to VMO-11 to hold the path prior to the first speed constraint. I can't come up with a scenario where this would actually occur.
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Happened to a JAL 747 a few years back as detailed in an incident report. Their Econ speed was very high at Mach .86 and during descent they entered a jet stream leading to a rapid speed increase. At first the automatics went to VNAV SPD at Mmo-11 knots but the speed still increased to redline.
It became a reportable incident due to the captain pulling on the controls with the autopilot still engaged and when the autopilot became disengaged there was one of those positive followed by negative g things that injured people. Sensitive controls up high was a factor.
Can be found on the Japanese accident investigation website.
It became a reportable incident due to the captain pulling on the controls with the autopilot still engaged and when the autopilot became disengaged there was one of those positive followed by negative g things that injured people. Sensitive controls up high was a factor.
Can be found on the Japanese accident investigation website.
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Wow. I guess that's one of the scenarios where you could see it, even if you had uplinked the descent wind forecast. Thanks for sharing this information.
[ADDENDUM] Here's the JAL accident report mentioned above by JammedStab. http://www.mlit.go.jp/jtsb/eng-air_report/JA8903.pdf
[ADDENDUM] Here's the JAL accident report mentioned above by JammedStab. http://www.mlit.go.jp/jtsb/eng-air_report/JA8903.pdf
Last edited by cf6-80c2b5f; 3rd Oct 2015 at 07:52.
