Originally posted by Evan
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Pilots Monkeying with CB's
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Originally posted by BoeingBobbyYou can thank ALPA and United airlines for that! No more flight engineers! Remember that most of the engineers started as mechanics. One of the things I missed most when we parked out 200's and I went over to the "glass" airplane, was looking over my right shoulder and asking the engineer, "what's going on" or "what have we got"?
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If pilots are pulling CB's because of nuisance, I think there is a problem with the alerting system, and this isn't really a problem with the pilots. Although I'm dealing with computer systems that run 7/24/365, I am really draconian about nuisance alerts. Either fix them (no false alarms) or shut them off. Whether we like it or not, a nuisance alert almost always results in people being trained to ignore it, or even worse, start ignoring all alerts or responding to them slower because they assume at first it is false.
IMO, I think this is an alerting defect.
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Originally posted by Schwartz View Post.
IMO, I think this is an alerting defect.
Now, look at the approach path for this accident. It's a non-standard approach in IMC over mountainous terrain. Under those circumstance you must live with the minor distraction of an essential line of defense. It also appears that the MSA on the charts is too low. This can happen in remote places. That's why you have to have to have that line of defense.
The first chart below shows the envelope out of landing configuration. If you have a 4000fpm closure rate on a mountain ahead, you can get a TERRAIN TERRAIN warning at 1500ft RA and the repeated PULL UP warnings.
The second chart shows the envelope in landing configuration (or in guarced-switch override). There's a lot more room there before the system starts to annoy you.
Bottom line: if you know how the system works, you can avoid most of these nuisance alerts by maintaining a reasonable separation from terrain and configuring everything appropriately. And, under these conditions, if you have to put up with a few nuisance alerts, live with it. It sure beats die without it.
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Originally posted by Evan View PostIt isn't. The terrain is there. They are flying an approach over mountainous terrain. EGPWS is predictive, so it is looking at closure rates towards terrain ahead as well as below. It doesn't like mountainous terrain, but that is a good thing, as mountaintops tend to be unforgiving to airplanes. There are multiple warning envelopes however (sink rate, closure rate, below glideslope, below miminums, gear not down, etc.). What they were probably getting here were terrain closure alerts for terrain AHEAD and sporadically below due to these mountaintops. But if the aircraft is in landing configuration, that warning envelope is only about 500ft vertical and 2200fpm closure rate. It's not hard to stay out of that envelope and if you are within it, especially in IMC, YOU SHOULD be getting distracted by EGPWS. Now, if you don't want to have full landing flaps out at that point, the envelope increases, but you can inhibit those warnings with a guarded switch on the captain-side panel, as long as the gear is out. If you don't bother to do this, and you are clean or in reduced flap settings, that alert envelope is going to extend up to about 1,700ft vertical depending on your closure rate. That could get bothersome.
Now, look at the approach path for this accident. It's a non-standard approach in IMC over mountainous terrain. Under those circumstance you must live with the minor distraction of an essential line of defense. It also appears that the MSA on the charts is too low. This can happen in remote places. That's why you have to have to have that line of defense.
The first chart below shows the envelope out of landing configuration. If you have a 4000fpm closure rate on a mountain ahead, you can get a TERRAIN TERRAIN warning at 1500ft RA and the repeated PULL UP warnings.
The second chart shows the envelope in landing configuration. There's a lot more room there before the system starts to annoy you.
Bottom line: if you know how the system works, you can avoid most of these nuisance alerts by maintaining a reasonable separation from terrain and configuring everything appropriately. And, under these conditions, if you have to put up with a few nuisance alerts, live with it. It sure beats die without it.
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Originally posted by Schwartz View PostI can show you that becoming aclimatised to nuisance alerts is as fatal as not having them. In some cases worse. If you train yourself not to react to an nuisance alert, you might ignore a similar alert at first that turns out to be fatal. Ignoring "a few nuisance" alerts can become just as deadly.
The thing is, the alerts other pilots at this airline were considering nuisance alerts were also real, valid alerts for the scenario and configuration. These were never nuisance alerts. It was hazardous flying.
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Originally posted by Evan View PostAgreed, if the pilots are not properly trained pilots. Properly trained pilots will know a) how to avoid or minimize nuisance alerts and b) to NEVER ignore them in IMC and c) NEVER to pull the alert CB unless it is seriously and definitely malfunctioning.
The thing is, the alerts other pilots at this airline were considering nuisance alerts were also real, valid alerts for the scenario and configuration. These were never nuisance alerts. It was hazardous flying.
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Originally posted by BoeingBobby View PostCare to back this up by fact? At my old company by the way, you were allowed one reset attempt of a CB.Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.
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Originally posted by 3WE View PostSupreme leader Donald (with your help) has given us the safest year ever in Aviation, nevertheless, you and your friends are reckless cowboys and are not to be trusted with yokes nor autopilots nor circuit breakers.
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Originally posted by BoeingBobby View PostHa! with your help needs to be in blue also!
--- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
--- Defend what you say with arguments, not by imposing your credentials ---
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Originally posted by 3WE View PostSupreme leader Donald (with your help) has given us the safest year ever in Aviation, nevertheless, you and your friends are reckless cowboys and are not to be trusted with yokes nor autopilots nor circuit breakers.
--- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
--- Defend what you say with arguments, not by imposing your credentials ---
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Originally posted by brianw999 View PostContact Breakers, not Cumulo Nimbus !! .....or have you trapped me into biting ?
Happy new year to all my non picture uploading clients !
Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.
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