Printable View
I am sure this question could be best answered here =] but I would like to know why most international departures us 31L ? does it have certain requirements for international destinations or anything else?. Maps would also be appreciated =] FYI TWA-Flt 800 used 31L on that faitful July night.
It's not that internationals use it, most flights in general use it, as it's usually the active runway.
Actually it is not soo much that but you have to kind of look at it from an operational standpoint. Having been an opp.'s agent before the longer the runway obviously the more weight you can take on and in the summer this makes a huge diffrence for example when Northwest had the 744 to Tokyo it was routinely the heaviest flight out of JFK . Winds and such defineately do play a factor but for example w ith the Continental 737 flight 1410 SRQ-EWR we would do the load plan for it etc... and above a certain tempature that being if memory serves correct after 89 degrees every degree F you deduct almost 400 pounds off of the max allowable departure weight. Some passengers once had to be pulled along with bags to go and people were pissed when out of ten thousand feet of runway she used 4400 feet to get off but you have ot calculate engine out performance etc etc etc.... And there is also the slope of the runways departing off of 32 there is a half degree dowward slope which greatly helps. There is a whole massive explaination I could actually go into but I will save all the boredom and tell you that it is primaraly wind and length as well as the fact they can split arrivals to the shorter one making it much easier to keep atc workload down
a take off is not as simple a procedure as just mashing the throttles into the eicas and praying you rotate before the end. to do it safely and legally you need a certain amount of runway to accelerate the airplane to Vr and then another distance to be able to stop the airplane should something happen before V1. it's called stopway and clearway. maybe later on i'll dig out the textbooks and look it up for you.
airplanes are heavy as you know, and a 744 full of fuel, pax, and cargo takes a good distace to get going. it also takes a good distance to stop it should they lose an engine or such... bottom line, JFK isn't going to use 31R for departures when they have the full length of 31L. 31R departures would limit the amount of payload airplanes can safely get into the air.
They will use 31R for some light departures (RJ's, light loaded 757/767's) but it does not make sense for the A340's / B747's/ B777's that are fully loaded. You have to remember all the hotels off the end of that runway and they need to have adequate clearance, not just get the wheels over the building.Quote:
Originally Posted by cancidas
Occasionally you will see a heavy go off of right though I have seen it several times and also seen pics online someplace. Generally lenghtn is the prohibiting factor try to use the longest available runway for a departure for a multitude of reasons some expressed above. Common logic thats all.