NetNews Usenet Archive 1993 #3/NN_1993_3.iso/spool/sci/aeronaut/airliner/304

Text File | 1993-01-22 | 3.9 KB | 81 lines

Newsgroups: sci.aeronautics.airliners
Path: sparky!uunet!stanford.edu!unixhub!ditka!ohare!news
From: [e-mail] (Robert Dorsett)
Subject: Re: Domestic Aircraft
X-Submission-Date: Thu, 21 Jan 93 10:01:31 CST
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Date: 22 Jan 93 02:59:46 PST
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In article <[e-mail]> Michael Weiss writes:
>
>In article <[e-mail]> [e-mail] (Karl Swartz) writes:
>>Also, where did this international stuff come from?  United planned
>>to use the 777 to replace the DC-10 on *domestic* routes, with the
>>747-400 and 767 (both -200 and -300) used for long international
>>routes.
>
>This had me wondering something.  Clearly, aircraft with long ranges (such as
>the 767, 747, DC-10, etc., etc.) can be flown directly from the US to any
>nation, so delivery is no more complicated than flying to the appropriate
>country.  What about the shorter-range aircraft, like the 727 and 737?  How
>do they get from the US to, say, the middle east?  Are their ranges just long
>enough to make it from New York to London?

Every class and model of airplane has specific operational guidelines.  EROPS
(extended-range operations) is an acronym that describes the regulatory en-
vironment.  These apply to any airplane, in varying degrees of severity,
regardless of whether it's a 737-500 or a 747-400.  For a twin, for instance,
the major issue is the reliability of the engines: for a trijet or four-
engined jet, a major issue can become the ability of the airplane to withstand
a cargo fire.  The objective is to establish a functional, statistical
"equivalency" of safety among all types operating a given route structure.

Note also that EROPS isn't necessarily concerned with over-water operations:
there are large areas of Asia, for instance, which would not satisfy legal
requirements for an alternate airport, with even a 120 minute alternate
envelope: runway length, quality of instrument approach, weather reporting,
and emergency services must all be considered.

Four-engined airplanes tend to set the "gold standard," for perceived
reliability reasons.  Thus, airplanes like the 747 may fly anywhere within
their legal operational envelope (i.e., source->destination + alternate)
without special aircrew or airplane certification.  Three-engined aircraft
have slightly tighter limitations, but may similarly be flown without special
operational requirements.

Two-engine airplanes have the tightest restrictions of all, requiring very
high, demonstrated engine reliability, and a high degree of systems redun-
dancy, to bring them up to a demonstrated equivalency of established wide-
body aircraft.  Special aircrew and operations-department training is also
required for this type of flying.  Extended-range twin operations is often
referred to as "ETOPS."

Ferry operations, which you refer to, are simply a subset of a generic EROPS
class, minus the unique particulars which might qualify an airplane for max.
range.  Obviously, this changes from airplane to airplane, but, yes, for
long-range delivery flights, there is no alternative but to stage it in
short hops, the length of which is contingent upon the capabilities of the
particular airplane and the crew available to make the flight. There are
plenty of short-hop alternates between Europe and the United States.  Even
light singles can be safely ferried, but extra attention must be paid to
survival equipment, avionics (communications), and weather.  The latter
has been discussed extensively on rec.aviation over the past couple of years,
where a couple of pilots have actually done this.






---
Robert Dorsett
[e-mail]
...cs.utexas.edu!cactus.org!rdd