Re: What's in a model number? (MD-95 Structural Specs)

From: (Larry Stone)
Organization: DECUServe
Date:         18 Dec 95 15:26:09 
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In article <airliners.1995.1857@ohare.Chicago.COM>, Don Stokes <> writes:

> I don't have much of a problem with the Boeing numbering.  As I understand
> it, a 757-222 is:
> 	Model:	757	Specifies engine size, number of engines,
> 			gross airframe configuration
> 	Series:	200	Specifies major variations from basic model in
> 			range, length, finer airframe configuration
> 		 22	Specifies airline-specific configuration, engines
> 			(type within range specified for model/series)
> 			cabin configuration etc (is there a name for this
> 			part of the number?).

But that isn't true. To expand on Karl's excellent example of the UA
747-400s, we have 24 of them of which 22 are 747-422s and 2 are
747-451s. Of the 22 747-422s, 6 have one cabin configuration
(36/123/142) while the 22 are 18/80/320, the same as the 2 747-451s. So
the airline part of the model is telling us nothing about the cabin

I believe (but am not all sure) that each configuration requires an STC
(supplemental type certificate) which does, in a very techinical sense,
make the planes different models but the Boeing model number is not
affected by the issuance of an STC.

At least for United, you can tell something about the plane's
configuration from the "nose number" (which is also on the tail now).
The nose number is a 4 digit number where the first digit indicates the
major fleet (747, DC-10, etc.), the second is the sub-fleet (different
configurations), and the last two match the last two digits of the
plane's registration number. The two 747-451s and the 16 747-422s with
the 18/80/320 seating all have the same first two digits (81).

Larry Stone                             | United Airlines
VAX and HP-UX Systems Administrator     | Maintenance Operations Center                | San Francisco, CA  415-634-4725
All opinions are mine, not United's.