|Quoting hivue (Reply 29):|
Thanks for the informative replies. So could it be a valid accusation to say that the crew let the airplane's automation handle situational awareness?
Sort of. Airliners typically get takeoff data by ACARS messaging. You enter the runway (and intersection if applicable), runway condition, and weight. It comes back with your V speeds and single engine T/O procedure (if it isn't standard). From what I gathered above, they entered the incorrect intersection into the ACARS box so it spit back "good numbers" and they took it.
Technology is quirky. If they were sending for new numbers while taxiing, its pretty easy to make a mistake like this. I was once in Newark getting takeoff data but the ACARS system thought we were in Boston. Both have a runway 22R. When it spat out the numbers, they looked good, but upon close examination we saw it said Boston. If it had been in an area with mountainous terrain and you can an engine, the airport likely has a special profile for avoiding "Cumulo Granites" (mountains). If your takeoff data doesn't reflect the procedure, and its at night, you simply wont have the available thrust to climb out of trouble.
Another interesting fact is that your single engine procedure can change depending on the intersection of the SAME runway. Without getting into too much detail, imagine a 3D cone projecting off of the starting point of the takeoff roll. it expands vertically and horizontally the further down the runway you go. any terrain, high structures, or prohibited areas that fall within this cone could trigger a special engine out procedure. Thus starting the roll further down the runway could put something in that cone that wouldn't be there with a full length takeoff and vice versa. Not usually an issue but its another "gotcha" that can sneak up on you if you get too complacent.
Expanding further on what Longhauler said, we almost always do de-rated take offs. It saves wear and tear on the engines. I would imagine (and judging from a post above was correct) that 7,800 feet of available runway simply isn't enough for a 777-300ER...especially if its hot. If it can do it, it will certainly be a "full blow" (max thrust) takeoff or close to it.
That being said, intersection departures are not unheard of. Newark typically uses 22R at W, O'hare uses 28R(?) at T10, etc. I have flown in and out of MIA
a few times and don't recall using an intersection but that was a while ago.
In this case, I looked at the airport charts when i made my earlier post and i looked for the intersection, looked at the available runway, and my gut reaction was "no" just based on ballpark numbers.
The plane is obviously heavy. Why risk a high speed abort on less available runway? Why re-brief and increase your workload (if offered during the taxi out), Why lower the safety margin at all? Someone in that cockpit should have spoken up and they are pretty lucky they aren't all dead.
It is always darkest before the sun comes up.