Boeing revises ranges of their aircraft

I already wrote back in 2012 that there is something not adding up in Boeing's range esimations for the B737MAX. Now Boeing officially revised the range numbers for all Boeing aircraft.
Boeing says this has to do with revised assumptions for pax, bags and seat weights. We don't know how Boeing revised those numbers, but as I wrote back then something did not add up from the beginning when comparing the range of the B737NG with the B737MAX.

With a range 4% shorter now for the B737MAX-8 than before the comparison to the old number for the B737NG would make sense, but the new range for the B737-800NG dropped by almost 5%. So it still does not make sense when directly comparing  the numbers...
UPDATE: Aviation Week reports that the extra weight per pax/bags and seat is 15lbs. Let's have a look at some numbers:
  • The B737MAX-7 "looses" 500nm with 126 pax and therefore a payload that is higher by 1890lbs than before (126pax*15lbs/pax).
  • The B737MAX-8 "looses" only 145nm, although payload is higher by 2430lbs (162pax * 15lbs/pax)
  • The MAX200 "looses" 645nm. Payload is higher by 3000lbs (200pax*15lbs/pax)
Comparing the -MAX7 and the -MAX8 makes me wonder why the MAX-8 only looses 0.06nm/lbs. The -MAX7 looses 0.26nm/lbs.
Comparing the -MAX8 and the -MAX200 us even more intriguing. It is almost the same aircraft, but the -MAX8 looses 0.06nm/lbs and the -MAX200 looses 0.215nm/lbs.

This looks weird to me and Boeing should explain these differences more in detail.

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