inadvertent IMC in Bell 407

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Keith Smith
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Joined: Sat Oct 09, 2010 8:38 pm
Location: Pompton Plains, NJ
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inadvertent IMC in Bell 407

Post by Keith Smith »

This happened last night during a quick hop in the 407. I checked the METARs but neglected to check the forecast. While I was enroute, ForeFilght was showing IMC at Ramona, and then at Palomar. The sim eventually caught up so I had to pick up a clearance and shoot my first ILS in a helicopter.

Twitch highlight is here: http://www.twitch.tv/ksmith_pe/v/20939777

Correction to the commentary in the video, once on the glideslope, there wouldn't have been a need for me to have ATC identify WUNUB. Using the altitude on the glideslope would've been ok.
Keith Smith
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Joined: Sat Oct 09, 2010 8:38 pm
Location: Pompton Plains, NJ
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Re: inadvertent IMC in Bell 407

Post by Keith Smith »

And here's an external view of the landing and taxi: http://www.twitch.tv/ksmith_pe/v/20942359

Nothing exciting, but it's taken quite a long time to get to the point where I can land a blender within a given zipcode.
asad112
Posts: 41
Joined: Fri Nov 14, 2014 1:54 pm

Re: inadvertent IMC in Bell 407

Post by asad112 »

Caught the tail-end of that last night, nice work. But one question, do you consider that fun? I usually find the simulator more enjoyable when I don't have to shower afterwards. :)
Keith Smith
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Joined: Sat Oct 09, 2010 8:38 pm
Location: Pompton Plains, NJ
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Re: inadvertent IMC in Bell 407

Post by Keith Smith »

Oh, that absolutely was fun.

Peter and I talked for quite a while about the WUNUB situation. You pretty much have to do the math to work out the altitude of the glideslope at WUNUB (in this case, it's 2720, about 120ft above the stepdown). It would take a pretty massive temperature differential to cause the glideslope to be lower than an indicated altitude of 2600.

Still, it's an interesting gotcha. The title of the approach says "ILS", and they're right, technically speaking you do NOT need anything other than ILS to fly from the FAF onwards. The problem is the step downs outside the FAF aren't represented in the title of the approach.

So, math saves the day, but it's still a strange scenario.

If anyone is wondering why this is a big deal, it's because blindly following the glideslope once you intercept it from any ol' distance can cause you all sorts of problems at a place like LAX where the published stepdown altitude and the altitude of the glideslope are so close together that a significant change in temperature can result in the glideslope being BELOW the stepdown altitudes, resulting in a violation of the procedure if you follow the glideslope too soon. This is why it's important to monitor the stepdowns if you elect to follow the glideslope prior to the FAF. In this case, I didn't have that luxury because I had no way to identify WUNUB.
Kerbo
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Joined: Tue Feb 17, 2015 12:58 pm
Location: St Louis, MO, USA

Re: inadvertent IMC in Bell 407

Post by Kerbo »

Keith Smith wrote:And here's an external view of the landing and taxi: http://www.twitch.tv/ksmith_pe/v/20942359
I've been trying to resist the urge to buy the Dreamfoil 407 because I barely have time to fly what I already have. Your cool videos are not helping. :P

Must. resist. whirly. spinny. thing...
Kerbo on YouTube or Twitch
armchair sim pilot
usual call sign: N1676L
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