rampart
Topic Author
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Clear Ice In My Yard, From An Airplane?

Sun Dec 12, 2010 3:03 pm

I know there was a thread on blue toilet ice a few weeks ago. Not the case here.

Yesterday morning, In my backyard and on my house roof (I was installing Christmas lights!), I found chunks of cylindrical shaped, clear ice. Some was about 2cm in diamater, none longer than 5cm, but it was evident that there might have been pieces of what was a longer chunk of ice. It had what I would describe as streamline, teardrop (airfoil?) shape in cross-section. Some chunks had linear, molded grooves around the circumference, I doubt of natural form.

Here's what it could NOT have been:
Hail. Would have been enormous if so. Clear skies, no thunderstorms previous night. Temps in the low 20s.
Icecicle off the house. No melting to produce an icicle, not enough rain or snow in previous days to produce large icecicles. No icicles anywhere nearby, or on neighbors' houses.
Blue ice. It was clear ice, like ice cube ice from the freezer.

So, I'm guessing it came off an airplane as some sort of icing on the structures of the plane. Could someone confirm this, or correct me? My house in Morris County is directly under approaches for either EWR or MMU, so plenty of traffic. Since the sky was clear all morning, I don't know that there would have been icing conditions anywhere in the atmosphere, but could ice remain on a plane coming from a different destination?

-Rampart
 
goboeing
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RE: Clear Ice In My Yard, From An Airplane?

Sun Dec 12, 2010 5:45 pm

Sure, it has to fall off somewhere. Either it melts if it's on a surface that is heated (wing, engines, etc.) or it stays on for quite a while after the ice is done accumulating if it's cold enough. Depends on where it is and how good it's stuck on there.

The horizontal stabilizer on the E-170 series is not heated. This is an example of an area that can accumulate ice and it will stay there for a while. Often it is still there at the gate on arrival, but it could slide off anywhere between the source and the gate.
 
Northwest727
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RE: Clear Ice In My Yard, From An Airplane?

Sun Dec 12, 2010 6:00 pm

Quoting GoBoeing (Reply 1):
The horizontal stabilizer on the E-170 series is not heated. This is an example of an area that can accumulate ice and it will stay there for a while. Often it is still there at the gate on arrival, but it could slide off anywhere between the source and the gate.

Any reason as to why it is not heated? I would think the airplane would be at high risk of stalling the horizontal stabilizer in icing conditions...
 
tdscanuck
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RE: Clear Ice In My Yard, From An Airplane?

Sun Dec 12, 2010 6:08 pm

Quoting Northwest727 (Reply 2):
Any reason as to why it is not heated?

No need to...I'm not aware of any airliner that has anti-ice/de-ice on the empennage.

Quoting Northwest727 (Reply 2):
I would think the airplane would be at high risk of stalling the horizontal stabilizer in icing conditions...

The horizontal stab doesn't operate anywhere close to stalling within the normal operating envelope. You do have to prove, via icing testing during certification, that you can get ice accumulation on all the non-protected surfaces (usually horizontal tail and outer wings) and still maintain adequate control.

Tom.
 
rampart
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RE: Clear Ice In My Yard, From An Airplane?

Sun Dec 12, 2010 6:47 pm

Quoting GoBoeing (Reply 1):
Sure, it has to fall off somewhere.

Interesting. From what reports we hear, "blue ice" is somewhat uncommon (or at least falling into populated areas). I assume structure icing is more common, so ice does have to fall off somewhere, yet I've never heard of this causing a problem. One would think this sort of hazard becomes an issue under airport approaches, and one more concern for "nimbies". Or is it pretty rare, too?

-Rampart
 
Northwest727
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Joined: Sat Jul 30, 2005 10:38 am

RE: Clear Ice In My Yard, From An Airplane?

Sun Dec 12, 2010 9:48 pm

Quoting tdscanuck (Reply 3):
No need to...I'm not aware of any airliner that has anti-ice/de-ice on the empennage.

I know the Dash 8 and Avro RJ85 has deice boots/anti-ice surfaces of the horizontal stabilizer, but you are right about other jet aircraft. Huh...I always thought the "silverish part" on the leading edges of the horizontal stabilizers were the anti-ice, I guess not. Learn something new every day.

Quoting tdscanuck (Reply 3):

The horizontal stab doesn't operate anywhere close to stalling within the normal operating envelope. You do have to prove, via icing testing during certification, that you can get ice accumulation on all the non-protected surfaces (usually horizontal tail and outer wings) and still maintain adequate control.

Thanks for the info.
 
goboeing
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Joined: Mon Jun 05, 2000 5:31 am

RE: Clear Ice In My Yard, From An Airplane?

Mon Dec 13, 2010 12:45 am

Quoting rampart (Reply 4):
I assume structure icing is more common, so ice does have to fall off somewhere, yet I've never heard of this causing a problem. One would think this sort of hazard becomes an issue under airport approaches, and one more concern for "nimbies". Or is it pretty rare, too?

It's probably fairly rare as it only falls off in a large piece under certain conditions.

Some conditions it melts off. Other conditions it is cold enough that it just stays there for the approach and landing and taxi in and the entire time on the ground until it gets sprayed off on the next taxi for takeoff.

You may also find this interesting. Take a look at approach plates for Tokyo Narita and you'll see this message to pilots:

Gear down operation on approach to Rwy 34L / Rwy 34R - Unless the safety of the flight will be compromised, aircraft on approach to Rwy 34L / Rwy 34R from the seashore are required to complete gear down and locked prior to IYQ 12.3 DME (NRE 14 DME) for Rwy 34L and ITJ 13.6 DME (HKE 15 DME) for Rwy 34R. This requirement is intended to prevent ice blocks from falling to the ground from the aircraft.

www.fly-sea.com/charts/RJAA.pdf and go to page 29, page 20-9L under the arrival section.
 
tdscanuck
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RE: Clear Ice In My Yard, From An Airplane?

Mon Dec 13, 2010 1:28 am

Quoting Northwest727 (Reply 5):
Huh...I always thought the "silverish part" on the leading edges of the horizontal stabilizers were the anti-ice, I guess not.

The "silverish part" is still bare metal, just like the leading edges of the wings, so they're visually identical. But, on the non-anti-iced surfaces, it's done that way for erosion mitigation rather than anti-ice heating.

Tom.
 
rjsampson
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RE: Clear Ice In My Yard, From An Airplane?

Mon Dec 13, 2010 1:49 am

I kind of doubt it came from an airplane.

Since you found multiple chunks, it's unlikely that ice falling from an aircraft wouldn't scatter considerably; you wouldn't see them grouped like that. If, on the other hand, these chunks fit together in some way, that would be a different story.
 
rampart
Topic Author
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RE: Clear Ice In My Yard, From An Airplane?

Mon Dec 13, 2010 12:22 pm

Quoting RJSampson (Reply 8):
I kind of doubt it came from an airplane.

Since you found multiple chunks, it's unlikely that ice falling from an aircraft wouldn't scatter considerably; you wouldn't see them grouped like that. If, on the other hand, these chunks fit together in some way, that would be a different story.


I take your point, but would have a very hard time envisioning any other cause for the ice, as I mentioned above.

I suspect it did come as one piece and shattered on impact. Since I found a piece on my roof, that's where it may have hit first. Other pieces were scattered on my deck and patio (near the roof), and a few out on the lawn, a bit farther but perhaps bounced? All the larger pieces had that similar cross-section shape, sort of tear-drop shaped. I think they were melted too much to be able to fit them back together definitively. I did save one piece, it's in the freezer in a ziploc bag.  

-Rampart
 
Northwest727
Posts: 379
Joined: Sat Jul 30, 2005 10:38 am

RE: Clear Ice In My Yard, From An Airplane?

Mon Dec 13, 2010 1:39 pm

Quoting tdscanuck (Reply 7):
The "silverish part" is still bare metal, just like the leading edges of the wings, so they're visually identical. But, on the non-anti-iced surfaces, it's done that way for erosion mitigation rather than anti-ice heating.

That makes sense, thanks!

Quoting rampart (Reply 9):
I did save one piece, it's in the freezer in a ziploc bag.

Take pictures of it and upload it to this thread before it someday melts!

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