NA From Germany, joined Dec 1999, 9605 posts, RR: 10 Posted (5 years 8 months 1 week 5 days 10 hours ago) and read 1815 times:
I found something strange in the succession of serial-numbers from Boeing aircraft. Why are, in the same fleet, higher (later) numbers used on older aircraft while newer aircraft carry lower numbers?
Very odd is that SFE and SFF seem to be from a later order as the serial-no is much higher (by more than 1500 frames) and the later built SFG and SFJ have low numbers again, SFJ even a number lower than SFA built 6 years earlier. What is the sense behind that?
I noticed the same with Korean Airs 744s, while LHs 744s serial-numbers are linear with age.
Dutchjet From Netherlands, joined Oct 2000, 7864 posts, RR: 58 Reply 1, posted (5 years 8 months 1 week 5 days 9 hours ago) and read 1758 times:
Quoting NA (Thread starter): found something strange in the succession of serial-numbers from Boeing aircraft. Why are, in the same fleet, higher (later) numbers used on older aircraft while newer aircraft carry lower numbers
It depends upon when the aircraft was ordered.......an aircraft ordered in 1995 but delivered in 2000 would carry a lower serial number than an aircraft ordered in 1997 and delivered in 1998.
Thus, with respect to the SQ aircraft that you mentioned, SFE/SFF were probably ordered separately from the other 744Fs that you list.
NA From Germany, joined Dec 1999, 9605 posts, RR: 10 Reply 2, posted (5 years 8 months 1 week 5 days 9 hours ago) and read 1738 times:
There must be a method to the madness, I agree.
That SFE/SFF are from a later order seems clear, but why were they built earlier than -apparently- identical airplanes of the same fleet ordered earlier? Why weren´t the earlier numbers used first? Maybe the specifications of the aircraft are a bit different, SFG/SFJ differing from the others? I can´t think of any other sensemaking reason.
Dutchjet From Netherlands, joined Oct 2000, 7864 posts, RR: 58 Reply 3, posted (5 years 8 months 1 week 5 days 9 hours ago) and read 1724 times:
Quoting NA (Reply 2): That SFE/SFF are from a later order seems clear, but why were they built earlier than -apparently- identical airplanes of the same fleet ordered earlier?
Why were they built earlier? Because thats what customer SQ requested and negotiated. Boeing does not swap serial numbers around.....the numbers for the later delivered airplanes were already assigned.
NA From Germany, joined Dec 1999, 9605 posts, RR: 10 Reply 5, posted (5 years 8 months 1 week 5 days 9 hours ago) and read 1703 times:
You mean, in this example, Boeing had already assigned serial-no.26558 to be line-number 1173 when SIA suddenly wanted more freighters built earlier, so 28263 could become line-no.1094? Didn´t know that Boeing fixes these numbers to line-numbers sometimes already many years before its been built.
Rivet42 From United Kingdom, joined Aug 2005, 817 posts, RR: 1 Reply 6, posted (5 years 8 months 1 week 5 days 9 hours ago) and read 1670 times:
You need to understand that there is no direct relationship between frame numbers and build sequence. Frame numbers are allocated as aircraft are ordered, regardless of when they might be build and delivered. Thus, whilst I don't have the data to hand at present, SQ Cargo most likely added aircraft to their initial order at a later date (or two later dates, judging by the two higher but unrelated frame numbers), but managed to negotiate earlier delivery of those two aircraft - possibly as a result of another 747 customer delaying or cancelling an order thereby freeing up slots on the production line.
Personally, I don't pay much attention to Boeing frame numbers, my records are based on the line number, as this - also unique for each production line - gives a true(r) sequence of build, and, more or less (though not always), delivery. On my database the frame number is merely a reference field, which holds no significance other than to indicate order sequence (which is pretty much meaningless in itself).
Tdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 81 Reply 7, posted (5 years 8 months 1 week 5 days 8 hours ago) and read 1634 times:
Quoting NA (Reply 5): You mean, in this example, Boeing had already assigned serial-no.26558 to be line-number 1173 when SIA suddenly wanted more freighters built earlier, so 28263 could become line-no.1094?
No, I mean they didn't know that S/N 26558 would be L/N 1173 at the time they assigned the S/N. Definition of the airplane (which sets the serial number) is a whole separate process from when it gets built (which sets the line number). An aircraft at Boeing gets a variable number and serial number before it gets a line number.
MEA-707 From Netherlands, joined Nov 1999, 4117 posts, RR: 37 Reply 8, posted (5 years 8 months 1 week 5 days 1 hour ago) and read 1487 times:
Quoting NA (Reply 5): Boeing had already assigned serial-no.26558 to be line-number 1173
Adding to Toms fine explanation; when they assigned serial nr 26558, they put a delivery date (at least something like a month or a quarter) , specifications and finance schemes etc. in the contract.
As monthly production goes up and down overyears, they had no clue it would become 1173 til about a year before delivery BUT they knew they approximate delivery date.
nobody has ever died from hard work, but why take the risk?
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