Bangor Maine - private jet w/8 crash

adk said:
It's pretty apparent that these pilots used the "light snow" category of their holdover table. I assume that they did this because the METAR said "light snow." It's pretty apparent that they were unaware that they should have gone to the separate "Snowfall Intensities as a Function of Prevailing Visibility" chart to figure out that even though the METAR said "light snow" the deicing holdover tables considered it to be Moderate snow based on temperature and visibility.

So, one human factors issue I think would be an easy fix: in the holdover tables, stop using terms to describe the snow that also appear in the METAR but do not directly correlate. In the holdover tables, call it something else. Maybe snowfall intensity 1-4 instead of very light to heavy snow? I don't know. But something. Not knowing that "light snow doesn't always mean light snow" seems like a predictable and preventable error for crews who don't deice often.
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We have a fancy de-ice app now that grabs the local METAR and applies it for us. Now of course, common sense should still apply which the other week in AMS we did a cabin check before departure as the snow was turning more toward pellets.
 
I'm pretty sure most airlines use an app for holdover times now. But let's be real, most part 91 flight departments aren't going to pay for that subscription since there aren't going to be LWE sensors installed at most GA fields. And a part 91 flight department from Texas REALLY isn't going to pay for that app subscription.
 
adk said:
I'm pretty sure most airlines use an app for holdover times now. But let's be real, most part 91 flight departments aren't going to pay for that subscription since there aren't going to be LWE sensors installed at most GA fields. And a part 91 flight department from Texas REALLY isn't going to pay for that app subscription.
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Sadly true, I've spent my entire career in 121 outside of instructing and always cringe/laugh/sigh when I hear how some of the 91/135 world operates.
 
adk said:
It's pretty apparent that these pilots used the "light snow" category of their holdover table. I assume that they did this because the METAR said "light snow." It's pretty apparent that they were unaware that they should have gone to the separate "Snowfall Intensities as a Function of Prevailing Visibility" chart to figure out that even though the METAR said "light snow" the deicing holdover tables considered it to be Moderate snow based on temperature and visibility.

So, one human factors issue I think would be an easy fix: in the holdover tables, stop using terms to describe the snow that also appear in the METAR but do not directly correlate. In the holdover tables, call it something else. Maybe snowfall intensity 1-4 instead of very light to heavy snow? I don't know. But something. Not knowing that "light snow doesn't always mean light snow" seems like a predictable and preventable error for crews who don't deice often.
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If this was the case, then this is a training issue.

Prevailing visibility has driven snowfall intensity for holdover times as long as I've been flying airliners, which is coming up on 20 years.
 
jtrain609 said:
If this was the case, then this is a training issue.

Prevailing visibility has driven snowfall intensity for holdover times as long as I've been flying airliners, which is coming up on 20 years.
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Sure, there were a lot of holes in the Swiss cheese that lined up that night, and improper application of holdover times is probably one of them. . But I don’t think taking the stance of “well they should have understood deicing better and that’s that” is the most optimal way to make things safer going forward. That statement is certainly accurate, but there are several other “holes un the cheese” that we can try to close.
 
bike21 said:
Sadly true, I've spent my entire career in 121 outside of instructing and always cringe/laugh/sigh when I hear how some of the 91/135 world operates.
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Like I said earlier, you’re good at what you do regularly. Airline pilots are great at deicing and operating in complex high volume environments. But just like a 91 department from Houston might not know a ton about deicing…I’d wager most major airline pilots aren’t fantastic at things like nontowered airport ops or flight planning/performance. By and large, I’d guess that 121 training is more consistent, but there are still a lot of good professional departments outside the airlines.
 
adk said:
Sure, there were a lot of holes in the Swiss cheese that lined up that night, and improper application of holdover times is probably one of them. . But I don’t think taking the stance of “well they should have understood deicing better and that’s that” is the most optimal way to make things safer going forward. That statement is certainly accurate, but there are several other “holes un the cheese” that we can try to close.
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Overhaul the ENTIRE deicing procedure.

Canada had a near miss with icing with a DHC8

When CANADA has a problem with icing, in a FRAKKING Dash-8...
It means there is a systemic problem with the entire program.
 
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