Nobody knows....
I do know personally one of the pilots and he is top notch, which leads me to discount some of the dumber theories.
There was mention about oil pressure? If they shut down an engine and it was slippery/icy then as mentioned controllability may have been an issue as well as being prohibited by company policy to do a single engine taxi if contaminated.
Prior to 777 I've only flown turboprops and 3 or 4 engine jets, but all were much easier to taxi with an engine shut down
Last edited by casablanca; 24th Nov 2015 at 16:57.