Re: Fracturing the Pacific

Date:         27 Aug 97 03:57:54 
From:         kls@ohare.Chicago.COM (Karl Swartz)
Organization: Chicago Software Works, Menlo Park, California
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>There are a large number of airfields in northern Siberia with long runways
>built by the Soviets for their Air Defense Force and fewer but with even
>longer runways built for their Air Force. Unless a large number of alternates
>exist for any point along each flight path, the routes will change daily in
>the winter based on which airfields can be cleared of snow.

Unless I've missed something, with the early 90 minute ETOPS for
trans-Atlantic service, if Sondre Stromfjord was unavailable, there
were no alternates for that portion of the flight and they therefore
were forced to cancel.  O'Hare very rarely closes completely, and I
would bet that the Russians are even more practiced at snow removal
and that they make damned sure their Air Defense Force bases are
not closed for the winter.

>> Flying JFK-HKG via N78 E164 keeps the flight within 180 minutes of
>> either Fairbanks or Magadan (at 757 engine-out speeds, with none of
>> the other alternates mentioned above required) yet adds only 8 miles
>> (0.099%) to the direct distance.

>That's certainly a trivial increase, but what happens on those days when
>Magadan is unavailable and winds are unfavorable?

Same thing as when Sondre Stromfjord was unavailable -- cancel the
flight.  Another reason why having Dikson or a similarly located
alternate would be desireable, even if it's technically possible to
fly without it.  (Non-ETOPS crossings of the North Atlantic in twins
are quite possible.  For a 757, the penalty was calculated as a 13.5%
increase in flight time over a 3- or 4-engined aircraft, a 3,250 kg
greater fuel burn, and cancellations about three times more often
than even 90-minute ETOPS flights.)

>> JFK-SIN does not appear to need any deviation.

>True on days that the alternates are available. I just doubt this would be
>more than, say, 300 days per year, even if the Russian government allows
>military bases to be used as alternates. Again, this is highly speculative.

Yes, highly speculative.  I don't see any basis whatsoever for the
"300 days per year" figure.  I could pick 360 or 180 with similar
confidence.

--
Karl Swartz	|Home	kls@chicago.com
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