I am flying melb to Darwin shortly and have noticed Qantas uses 737/800 planes and not the A330 as I'm flying business the A330 would be better especially with the new business sea

I am flying melb to Darwin shortly and have noticed Qantas uses 737/800 planes and not the A330 as I'm flying business the A330 would be better especially with the new business seats .does anyone know why the A330 is not used on such a long trip

This is simply due to the fact that there is insignificant demand for a wide body on the MEL-DRW route compared to say Perth where there are more pax. It also isn't uncommon for 737's to fly routes that long eg. MEL-BME and DPS

Agreed. This is far from the strongest route on the network; VA and JQ fly it just once daily and QF only flies it five times a week.

I am assuming you go via ADL where the flight number and sometimes on the way home aircraft changes where the 738's are used the most.