I do not know your aviation knowledge background, so I use simple words to explain. Hope you do not mind that I use the 747-200, as I am more familiar with that aircraft than the 717... and give you speeds that make sense.
Suppose I am at JFK
, 150 passengers only, and the airline tells me to stop in MIA
, to take another 200 passengers bound for EZE
. I will probably be given runway 31L, because of the LH
turn on departure and heading South.
My plane is obviously very light, few passengers, enough fuel to make MIA
+ reserves, as you said, the 15,000 feet-long runway is an "overkill"... Say my weight is only 500,000 lbs. My speed V1 would be 120... I could do with a short 7,000 feet long runway (half the length of that runway length available).
Despite the fact that I have tremendous "excess of concrete" in front of me, if an engine failed at say, 125 knots... I would continue the takeoff, because that is THE procedure... Yet I know, that 15,000 feet long runway could accommodate a takeoff at 833,000 lbs, which would have a V1 speed of 170 knots. I could abort for an engine failure at 165, and still "stop the plane"...
Even though it is strange to you maybe, yet, standardization and procedures require me to take my decision go/no-go at 120 knots, for my takeoff with the light airplane going to MIA
... That is what "the book" says...
Is that sufficient explanation...?
Happy contrails -
[Edited 2003-11-12 02:04:12]
[Edited 2003-11-12 02:07:10]