Yup, it's optional:
- Capture.PNG (206.88 KiB) Viewed 1808 times
Full source (warning, 389 page PDF):
http://www.smartcockpit.com/docs/a350-9 ... pilots.pdfMy best guess is that airlines decide whether or not to equip the system based on the longest routes they use the aircraft on. The longer the routes, the more fuel they have onboard upon takeoff, the greater the need for a nozzle, should SHTF right after takeoff.
Finnair might have decided that their A359 would be able to sustain an overweight landing, in case they need to return straight away.
IIRC, BA don't have a jettison system on their A350-1000 either.
Ideology: The mistaken belief that your beliefs are neither beliefs nor mistaken.