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Date: Fri, 12 Nov 2010 07:29:29 -0500
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From: Hamid Wasti <hwasti@lm50.com>
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Subject: Re: [LML] Re: iPad use in the cockpit
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The altitude and thermal specs are linked. At higher altitude, you have=20
less air molecules to take away the heat. Because of this, a device that =

will heat up to a certain temperature at sea level will heat up to a=20
higher temperature at 10,000 feet and an even higher temperature at=20
15,000 feet, assuming all else is equal. Put the other way, a device=20
that will function up to a certain ambient temperature at sea level will =

only operate to a lower ambient temperature at 10,000 feet and an even=20
lower ambient temperature at 15,000 feet.

I do not own an iPad, so I have no personal experience. However, there=20
have been a lot of reports about the iPad getting too hot and shutting=20
down when exposed to direct sunlight. These are reports at ground level=20
and some are claiming that it takes a little as 10 minutes. A Google=20
search reveals million+ hits, including the following from cNet and=20
Applr's own discussion forum:

http://reviews.cnet.com/8301-31747_7-20001749-243.html
http://discussions.info.apple.com/thread.jspa?threadID=3D2396808&start=3D=
0&tstart=3D0

Quite predictably, this has led to a good ol lawsuit. Here's a news=20
article and the actual filing:

http://www.bloomberg.com/news/2010-07-26/apple-sued-over-claims-ipad-tabl=
et-overheats-in-sunlight-warm-conditions.html
http://www.docstoc.com/docs/document-preview.aspx?doc_id=3D48234124

The following link, claiming to answering on behalf of iPad users,=20
acknowledges the existence of the problem and mocks people for being=20
unreasonable for trying to use the iPad in situations where these=20
problems can reasonably be expected to occur (their opinion of what is=20
"reasonable"):

http://www.theipadguide.com/content/books-have-better-heat-tolerance-ipad=
/7174901

I do not know if any of these reports are true, if the problems are=20
endemic or experienced by a few outliers. What I can tell you is that=20
whatever the experience at sea level, the thermal performance will be=20
worse at 8,000 feet in a IV-P and worse still at 15,000 ft in a Legacy=20
-- that is basic physics.

It is your call how much credence you want to put in these reports.=20
Whatever you decide, I would strongly urge you to thoroughly test=20
whatever hardware/software you want to use and push it to the limit in a =

realistic environment before you actually put it in service. The cockpit =

is no place for surprises!

Regards,

Hamid

Chris Zavatson wrote:
> Thanks for all the replies.
> One more question.  The apple specs show maximum operating altitude of =

> 10,000 feet.  If there is a good technical reason for this, it would=20
> seem rather limiting for our en-route use.  The operating temperature=20
> is also kind of pushing the upper limit when on the ground on hot=20
> summer days.  The temperature issue can be somewhat controlled, but=20
> the altitude exposure not so much.  Is this a CYA or other generic limi=
t?
>
>
>       Environmental requirements
>
>     * Operating temperature: 32=B0 to 95=B0 F (0=B0 to 35=B0 C)
>     * Nonoperating temperature: -4=B0 to 113=B0 F (-20=B0 to 45=B0 C)
>     * Relative humidity: 5% to 95% noncondensing
>     * Maximum operating altitude: 10,000 feet (3000 m)
>
>
> Chris Zavatson
>