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SFO 28L/28R  
User currently offlinelegacyins From United States of America, joined Aug 2003, 2022 posts, RR: 0
Posted (2 years 10 months 4 weeks 14 hours ago) and read 3356 times:

Most, if not all long haul flights to Asia/Europe depart from 28L / 28R at SFO. 28L is approximately 10, 600 ft and 28R is 11,500 ft. Sometimes I hear a particular flight request 28R for departure. I assume this is because it is heavy with paxs/fuel ect. While watching the flight depart, I usually noitce the flight rotate shortly after passing the intersecting runways of 1L/1R. Similarly, a heavy departing on 28L, usually departs shortly after passing the intersecting runways.

My question is, why do some aircraft request 28R for departure when they could use 28L, a shorter runway, witrh the same results?


John@SFO
12 replies: All unread, jump to last
 
User currently offlinewilco737 From Greenland, joined Jun 2004, 8904 posts, RR: 76
Reply 1, posted (2 years 10 months 4 weeks 14 hours ago) and read 3343 times:
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Quoting legacyins (Thread starter):
My question is, why do some aircraft request 28R for departure when they could use 28L, a shorter runway, witrh the same results?

The longer the runway the better. You should image the case that you have a problem and have to abort the take off. Then the longer the better. For the 'go' case the shorter runway is no problem as well, but the 'stop' case could get more restrictive and maybe you can carry less payload or less fuel.
We requested 28R for departure from SFO to FRA as well. Full PAX and a lot of fuel on the flight back, so we haven't had any restrictions on 28R and the 28L would've been possible as well, but a take off which didn't had a lot of margins. These safety margins were given on 28R, so we requested it and got it for take off.

wilco737
  



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User currently offlinefr8mech From United States of America, joined Sep 2005, 5098 posts, RR: 12
Reply 2, posted (2 years 10 months 4 weeks 14 hours ago) and read 3340 times:

Because runway behind you (or in this case, to your left) is like the airspace above you: useless in an emergency. The flight crews of heavily loaded aircraft should prefer a longer runway in order to provide that added cushion in case something goes wrong.


When seconds count...the police are minutes away. Never leave your cave without your club.
User currently onlinevikkyvik From United States of America, joined Jul 2003, 9399 posts, RR: 27
Reply 3, posted (2 years 10 months 4 weeks 14 hours ago) and read 3339 times:
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Quoting legacyins (Thread starter):

My question is, why do some aircraft request 28R for departure when they could use 28L, a shorter runway, witrh the same results?

I don't know the specific answer for SFO, but just because an airplane takes off at near the same spot doesn't mean it could use the other runway.

One answer could be the runway length that the airplane requires to reject the takeoff from V1. All other things being equal, a heavier aircraft will need more runway in which to stop. So using the longer runway could be predicated on that.

Far as I know there is data that airlines use for every aircraft type on every runway at every airport to which they fly. This will basically tell you how much weight you can put on an airplane for a specific runway, taking into account runway length, wind, weather, runway condition (dry, wet, icy, etc.), required climb gradients with an engine out, etc.

So it's not as straightforward as saying, oh they only used half the runway; they should have used the shorter one.  



"Two and a Half Men" was filmed in front of a live ostrich.
User currently offlineInnocuousFox From United States of America, joined Dec 2003, 2805 posts, RR: 15
Reply 4, posted (2 years 10 months 4 weeks 7 hours ago) and read 3284 times:

Remember that 28 L/R start at the same spot. Therefore, if they rotate at identical places (i.e. the 1's) the only difference is the runway remaining. Since, as you noted, the right side is longer than the left, the entirety of that distance is what is remaining.

To change gears for a second, ask yourself this... if the a/c are off the ground in 6000', why would they not be able to use a 6000' runway? Obviously, the answer has to do with the question, "what happens if I decide NOT to rotate?" It's all about the braking distance at that point. If you get to the 6000' mark and have to abort, it's going to take you a little while to slow down. The extra 1000' at the end might be the difference.



Dave Mark - Intrinsic Algorithm - Reducing the world to mathematical equations!
User currently offline26point2 From United States of America, joined Mar 2010, 786 posts, RR: 0
Reply 5, posted (2 years 10 months 4 weeks ago) and read 3214 times:

Also, for efficiency perhaps SFO prefers 28L for landing aircraft as the terminal is on the left side of the runway. This way aircraft aren't landing on the right and having to wait for aircraft to takeoff on the left before crossing. I've been a sitting duck a few times waiting there...not fun.

Just a wild ass guess really.

Fun fact: embedded runway centerline lights are not actually on the centerline but just to one side or the other. Which side is determined by which direction the plane will turn off the runway after landing to avoid the nose wheel thumping along over them. Check it out.


User currently onlinevikkyvik From United States of America, joined Jul 2003, 9399 posts, RR: 27
Reply 6, posted (2 years 10 months 3 weeks 6 days 23 hours ago) and read 3189 times:
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Quoting 26point2 (Reply 5):
Also, for efficiency perhaps SFO prefers 28L for landing aircraft as the terminal is on the left side of the runway. This way aircraft aren't landing on the right and having to wait for aircraft to takeoff on the left before crossing. I've been a sitting duck a few times waiting there...not fun.

Don't know about SFO, but other airports with parallel runways seem to typically use the closer runway for takeoffs, and the far runway for landings.

Examples would be BOS and LAX off the top of my head.

Of course there are exceptions - the cross-country flights I've been on from BOS have generally used 4R/22L for takeoff instead of 4L/22R (I assume that's a runway length thing). And the cargo aircraft from LAX seem to use 25L for takeoff instead of 25R (I assume that's because the cargo areas are located on that side of the runways).

Don't know or can't remember about other airports, but I wouldn't be surprised to find a similar setup at, say, DFW, PHX, etc.



"Two and a Half Men" was filmed in front of a live ostrich.
User currently offlineInnocuousFox From United States of America, joined Dec 2003, 2805 posts, RR: 15
Reply 7, posted (2 years 10 months 3 weeks 6 days 21 hours ago) and read 3146 times:

He's talking about pilot requests for the longer runways... not operational issues.


Dave Mark - Intrinsic Algorithm - Reducing the world to mathematical equations!
User currently offlinetimz From United States of America, joined Sep 1999, 6708 posts, RR: 7
Reply 8, posted (2 years 10 months 3 weeks 6 days 20 hours ago) and read 3140 times:

Quoting 26point2 (Reply 5):
perhaps SFO prefers 28L for landing aircraft
Quoting vikkyvik (Reply 6):
other airports with parallel runways seem to typically use the closer runway for takeoffs

At SFO 90%+ (?) of arrivals from the south land on 28L, 90%+ (?) of arrivals from the east land on 28R. Arrivals from the north might do their downwind NE or SW of the final, presumably based on which arrival stream has room for them at the time.

By the way-- nonstops to Europe off 1R aren't exactly common, but they're not real rare either.


User currently offlineBellerophon From United Kingdom, joined May 2002, 583 posts, RR: 59
Reply 9, posted (2 years 10 months 3 weeks 6 days 20 hours ago) and read 3137 times:

timz

...By the way-- nonstops to Europe off 1R aren't exactly common, but they're not real rare either...


True, however, I did once take-off from 19L in a B747 for a non-stop to Europe, and that is rare!


Best Regards

Bellerophon


User currently offlineAaron747 From Japan, joined Aug 2003, 7951 posts, RR: 26
Reply 10, posted (2 years 10 months 3 weeks 4 days 20 hours ago) and read 2913 times:

Quoting legacyins (Thread starter):
My question is, why do some aircraft request 28R for departure when they could use 28L, a shorter runway, witrh the same results?

For all the answer you'll ever need, I refer you to the story of Pan Am 845 in 1971:

http://en.wikipedia.org/wiki/Pan_Am_Flight_845



If you need someone to blame / throw a rock in the air / you'll hit someone guilty
User currently offlineapodino From United States of America, joined Apr 2005, 4124 posts, RR: 6
Reply 11, posted (2 years 10 months 2 weeks 1 day 14 hours ago) and read 2530 times:

Quoting vikkyvik (Reply 6):

Examples would be BOS and LAX off the top of my head.

Of course there are exceptions - the cross-country flights I've been on from BOS have generally used 4R/22L for takeoff instead of 4L/22R (I assume that's a runway length thing). And the cargo aircraft from LAX seem to use 25L for takeoff instead of 25R (I assume that's because the cargo areas are located on that side of the runways).

The biggest noteable exception is PHL, where in the West config, which is more common than East, 27L, the runway further from the terminals, is the primary departure runway with 27R being the main arrival runway.

I can elaborate a bit on BOS. 4L can not be used by Jets for departure for noise abatement reasons (even though 4R has a very simlar flight path and its used quite often), but even so runway 9 is the primary departure runway, but its only 7000 feet long, so the planes that are fueled up more (West Coast and Europre), will use 4R more, especially in the summer time.

22R is a very odd runway. I work for a regional airline that flies into BOS often. Runway 22R returns some very low MTOW's due to what Aerodata terms an Obstacle off the runway. Since the end of the field is the harbor, I don't know what obstacle there is. But strangely enough, on a hot day, the Takeoff performance numbers in BOS often tell me that we are too heavy to use runway 22R and we have to request 22L, in a CRJ. And this is just for flights to places like PIT or BUF. This has never made much sense to me here. But that is why you see 22L used often for BOS.


User currently onlinevikkyvik From United States of America, joined Jul 2003, 9399 posts, RR: 27
Reply 12, posted (2 years 10 months 2 weeks 1 day ago) and read 2449 times:
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Quoting apodino (Reply 11):
22R is a very odd runway. I work for a regional airline that flies into BOS often. Runway 22R returns some very low MTOW's due to what Aerodata terms an Obstacle off the runway. Since the end of the field is the harbor, I don't know what obstacle there is. But strangely enough, on a hot day, the Takeoff performance numbers in BOS often tell me that we are too heavy to use runway 22R and we have to request 22L, in a CRJ. And this is just for flights to places like PIT or BUF. This has never made much sense to me here. But that is why you see 22L used often for BOS.

My guess is the clearance required for ships in the channel between the airport and the Black Falcon shipping terminal. Or the cranes at the terminal.

Airnav says:

Obstructions:44 ft. boat, 670 ft. from runway, 10:1 slope to clear

But I'm not sure if that is talking about the approach end of 22R or the departure end.

http://www.airnav.com/airport/KBOS



"Two and a Half Men" was filmed in front of a live ostrich.
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