Re: Confusion over 777 variants.

From:         "Stefano P. Pagiola" <Spagiola@worldbank.org>
Date:         02 Dec 1997 13:23:31 -0500
Organization: WorldBank
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Karl Swartz wrote:
> ... the first two A300s built (A300B1 models -- add yet another
> to your list!) were 167'2" (50.97m) long.  The A300B2 and A300B4 were
> stretched to 175'11" (53.6m).  The slight difference you mention is from
> these versions to the current -600 models, which have a 21" (0.52m) plug
> aft of the wing along with the A310's rear fuselage and other changes.
> To make it even more confusing, the early versions are often referred
> to as simply an A300B4 (or A300B2) while the current models are called
> A300-600.  Yet the *correct* designation for the current models is
> A300B4-600!
> We could further confuse things by talking about the A300B4-2C, which
> was rechristened A300B4-200, and various other early designations.  To
> really make a mess, how 'bout the A300B10 and A300B11, which developed
> into the A310 and A340, respectively?  :-)


The complicated aspect of the Airbus naming scheme is that they changed it
several times. In the beginning, there were the B1, B2, and B4 models. As
you noted, the B1 is shorter. The B2 and B4 are the same length, but the
B4 has a higher gross weight. Initially, variants were specified with dash
numbers such as -1C or -2C. There was also a B2K-3C. Later, this was
changed to a system of dash numbers based on -yxx where y is the basic
variant, and xx is a code for the engine type. Thus a B4-203 is a B4
model, variant 200, with GE CF6 engines. But the old numbering scheme is
still cited in many places. To complicate things, unlike Boeing aircraft,
the designation of Airbus aircraft does change if the aircraft is
modified. As Karl noted, designations of Boeing aircraft never change once
the aircraft is built. So the 747-451s that United has remain -451s
because they were initially built for Northwest (Boeing customer code 51)
even though right now they have very little in common with other -451s and
much in common with United's own -422s.  Not so on Airbus aircraft. Do the
appropriate mods, and a -103 can become a -203. Airbus has since
standardized on the -yxx scheme, where y now indicates the basic model
(series 100, 200, etc) rather than sub-model, but the logic remains the
same.

> McDonnell-Douglas made it easy with the DC-10.  There are just four
> models:
>    -10   medium-range model
>    -30   long-range model
>    -40   -30 with JT9D engines
>    -15   -10 with high-rated engines from the -30
> Or is it easy?  Two DC-10-30s can be very different indeed, despite
> having the same model designation.

You forgot the DC-10-30ER. And of course, we'll soon be getting
MD-10s. But you're right, the Douglas designations were quite simple. On
the DC-9, the second digit of the dash number indicates the variant,
distinguishing the -31 from the -32 (higher gross weight variant), for
example. And here too, the designation changed if the aircraft was
modified. When they switched to MD-, however, this system got all mucked
up. You're right that two DC-10-30s can be very different (ask ValuJet
about their fleet of DC-9-30s). But so can two 747-451s. If the
designation isn't going to change once the aircraft leaves the factory
door, why not keep it simple?

To my mind, the current Airbus scheme is the most logical and informative
of the current schemes. By looking at an Airbus designation such as
A320-231 I can see both the series (200) and the engine (V2500, and if I
had a better memory I'd be able to say exactly which dash number of the
V2500). Moreover, the dash number tells me about the aircraft's CURRENT
state, not the state it was in when it left the factory. A Boeing
designation such as 747-451 also tells me the basic series (400), but
beyond that it only tells me who the aircraft was originally built for
(Northwest), and there are so many customer codes anyway that keeping
track of them all is near-impossible. It doesn't tell me anything else
about the aircraft. If I had encyclopedic knowledge, I might know which
engine type Northwest specified, and so what engine the aircraft is likely
to have.  Even major post-delivery modifications would not be reflected in
the designation, however, except informally eg 747-123 (F).

And as long as we're expressing opinions, let me add that I personally
dislike the ER and IGW suffixes that seem to be all the rage these days.
Consider a 777-200. There already is a -200IGW (formerly known as -200B).
But what happens if they go ahead with the -200X? That will involve a
further increase in gross weight. What will they call that? And will it
still make sense to call the -200IGW an IGW when there's an even higher
gross weight model around? If Boeing had stuck with -200A, -200B, etc,
then -200C would have been a natural progression. And what of the
767-400ER?  There is no 767-400, just a -400ER. Excuse me, but that's
"extended" compared to what?

Stefano Pagiola
--
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