If the -9ER was such a great idea, Boeing would have built it instead of the -10.
600+ orders show airlines are happy with the MAX-10 as is.
I don't see Boeing making any lineup tweaks for a while.
They are finally getting things going in the right direction.
The MAX9ER of course is not instead of the 10, it is additional. The 10 is perfect for capacity on short/Medium routes (most of the routes). After the 10 has arrived I do not see too many orders for the 9 in the future. A 9ER could cover the route lenghts where the 10 runs out of range. Also Boeing would have something to compete against the A321LR at least. The complexity seems to be manageable, as this 9ER would literally be a MAX10-Shrink.
But you are right, first Boeing of course needs to get the whole MAX right and running. But in the long run it could be worth doing.
There is currently no -9ER. And I would not discount the basic -9 yet. Assuming 100 kg pr pax w bags and full tanks of fuel, the types can carry:
-8 154 pax
-9 195 pax
-10 189 pax
So as a short-mid range peoplemover the -10 fits the bill. Need a descent load and say 5 hours or more range, go for the -9. The -8 is too weight limited.
Not sure what your point is. Given no take off restrictions, the -800 is generally tank volume limited for long sectors. Additional take off weight capacity doesn’t help it. It simply needs additional fuel to fly further. This is the reason why the range penalty gradient is so steep. You’re shedding weight to reduce drag/burn, not take more fuel. For longer range, it needs ACTs to carry the additional fuel. No commercial operator fitted ACT’s into -800’s.
-900ER is mostly the same. For any cabin config targeting long range flights, it needs an ACT. None of the USA carriers spec’d these. The only one I’m aware that did is Turkish.
Moving to the MAX 8, it continue to be fuel volume limited. It’s brochure range is listed at 3550nm and that’s without ACTs. MTOW rating is such that it take can take full tanks and normal cabin load out to that published range. Adding 2T to MTOW doesn’t increase its range.
The MAX 9 is also listed at 3550nm range, but it requires a ACT to get that far. It’s MTOW is such that it allows the ACT and standard cabin. I’m not aware of any carriers that have taken the ACT’s as the baseline version still flies plenty far on the standard tanks (further than a -900ER or -800)
I understand the MAX10 still requires an ACT to reach its’s brochure range (~3200nm).
The seating capacity difference between MAX 8 to MAX 9 is basically the same as between MAX 9 to MAX 10. I don’t have a link handy to the chart im about to reference. However, the take away is that the relative efficiency gain between MAX 8 and MAX 9 is nearly twice that as MAX 9 to MAX 10, meaning the 10’s advantage over the 9 is smaller than the 9’s advantage over the 8. This goes to the early days when the decision was made to size the 900 as it is, rather then further stretch to closer to A321 size. The additional work starts to drive cost up, commonality down, and reduces incremental advantages any bigger than -900.
That said, cost isn’t everything and the revenue advantage of the 10 has spoken relatively loudly. Enough routes need that extra capacity to justify the investment snd reap the slightly smaller CASM advantage as well.
I continue to think a 9 using the 10’s gear may be the new volume sales leader should it launch. It should nearly equal -8’s take off performance, which is the main aspect that’s held the -9 back, and picks up a sizable CASM advantage. The -10 performance is not better than the -9 so it will continue to face these operational challenges which effect sales to ROW.