Sorry Cactus, but your appreciation of TODR vs ASDA is scant to say the least. Firstly you are using apples vs oranges. Even if you said TODA vs ASDA, your so called 'balanced field' definition is wrong.
Lets pretend, for a moment, that you meant ASDR = TODR, I may buy into that...briefly, but thats only a definition of a Balanced Field, and operationally not all that common or desired. For instance, if you had a runway with obstacles in the 2nd, 3rd or final, and a subsequently reduced TOW for the grad., then why the hell would you want a balanced field? A long rwy like Sydney 16R for instance will bring you into a Brake Energy limit before you get to your other limits, and MTOW becomes the operational limit. Again your Balanced Field theory is devoid of reason. If you want to screw with your V1 / VR ratio to achieve this, other factors will prevent you from doing so. May I quote my boeing AFM.......
"The takeoff distances for this airplane are unbalanced because the V1 for a balanced field would normally exceed VR with anti-skid operating"
Now, 'wet' rwys can be a little more tricky, but watch your definition of 'wet' on groved rwys.
Further, and all Required / Available lengths aside, to judge the reasoning for departures from other than full length you must know all the factors effecting the performance of the airplane at the time.
What was its Actual TOW?
.....its limiting TOW - and its always nice to know if its RWY, brake temp or Obs related.
....and the margin.
So, and I hope I haven't bored you too much, the answer to why DJ did what they did is quite as simple as the ol' "Why does a dog lick its nuts?"
cheers
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