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Runway Lengths: PVD Vs. OGG  
User currently offlineBishop1 From , joined Dec 1969, posts, RR:
Posted (13 years 12 months 11 hours ago) and read 1666 times:

Greetings to all,

I have a curiosity question maybe someone could answer.

Living in Rhode Island, at the present time there is alot of controversy about runway length at PVD (whether to extend, approx. 7,800 ft to 9,000 ft). The airlines would like the longer runway to be able to fly coast to coast with a full load. Understandable for safety concerns.

Recently, I noticed, a few of the major carriers are flying or will start to fly 777's and 767-300's from Maui (OGG) to LAX, SFO and even as far as DFW (Dallas). OGG's main runway is no longer than ours at PVD.

If they are so concerned about PVD's main runway being too short for coast to coast flights, why would these same airlines allow the wide bodies to fly out of OGG? One would have to assume when these planes leave OGG that they are full.

Just had to ask.


7 replies: All unread, jump to last
 
User currently offlineJohn From United States of America, joined Sep 1999, 1374 posts, RR: 5
Reply 1, posted (13 years 11 months 3 weeks 4 days 1 hour ago) and read 1609 times:

This is a question that I can never seem to get answered. It just blows my mind! PVD's main runway, 5/23 is 7,166 ft long. SNA's runway is RIDICULOUSLY SHORT, at only 5,700ft! Just look at the range of some of the flights that operate out of there. It just amazes me! If CO can operate SNA-EWR nonstop or US SNA-PIT, UA SNA-ORD..etc. I'm sure UA or AA could operate a daily nonstop 757 PVD-LAX/SFO, no problem, and fill it up, too!Hell, the secondary runway at PVD is longer than the one at SNA, at a mere 6,081ft!As for OGG, this is an airport that has UA 777 service nonstop to LAX and SFO, for gods sake! They supposedly have only 7,000ft of concrete, there. I find this hard to believe. Is there an overrun area or displaced threshhold? Does UA ever take any weight penalties off that runway using 767-300 or 777 equipment?OK, now let's discuss this with the aircraft performance experts! This, I believe, IS a great question! Maybe we can finally get some answers.

User currently offlineOPNLguy From , joined Dec 1969, posts, RR:
Reply 2, posted (13 years 11 months 3 weeks 3 days 13 hours ago) and read 1589 times:

>>>I have a curiosity question maybe someone could answer. Living in Rhode Island, at the present time there is alot of controversy about runway length at PVD (whether to extend, approx. 7,800 ft to 9,000 ft). The airlines would like the longer runway to be able to fly coast to coast with a full load. Understandable for safety concerns.


Like the Hertz commercials say, "not exactly". It's NOT a safety concern, per se. Either a runway is long enough to allow takeoff at a particular weight (which, as you infer, varies with actual passenger load, but also, temp, winds, etc.) or it doesn't. If a flight is too heavy, weight is removed until it's again within max permissible limits. Another option is for the flight to make an additional stop enroute, thus reducing the total amount of fuel aboard, and making the aircraft lighter. A full flight PVD-LAX might have to operate PVD=PIT or PVD-IND first, and will thus require less fuel than the PVD-LAX option. The longer runways at PIT/IND, and the shorted total distance fromthere to LAX, will permit non-stop operation. If the PVD-LAX flight only had 50 folks on it, yeah, you'd be going non-stop.



>>>Recently, I noticed, a few of the major carriers are flying or will start to fly 777's and 767-300's from Maui (OGG) to LAX, SFO and even as far as DFW (Dallas). OGG's main runway is no longer than ours at PVD. If they are so concerned about PVD's main runway being too short for coast to coast flights, why would these same airlines allow the wide bodies to fly out of OGG? One would have to assume when these planes leave OGG that they are full.


This sort of relates to your first question, and yes, the assumption that OGG-LAX/SFO/DFW flights are FULL is just that--an assumption.

Without the benefit of charts here at the house to confirm these details, I'm going to assume that PVD and OGG are essentially at sea level elevations, and that there are no obstacles affecting performance. ((One could have a 10,000 foot runway, but if there are obstructions (terrain, buildings, etc.) within a couple of miles from the departure end of the runway, that long runway is not going to provide optimal weights as an obstacle-free runway would.)) Runway length is important, and the longer the better, but it's just one factor in the context of your question.

Allow me to make a simplistic side-by-side comparison, assuming all the following data:

OGG-XYZ PVD-LAX
3000nm 3000nm (Assumed distance)
460kt 460kt (Assumed 767 true air speed)
+75kt -75kt (Assumed tail/headwind)
535kt 385kt (Resulting groundspeed)
5:36 7:47 (Resulting time enroute)
56,100 78,000 (Resulting 767 fuel burn, @10,000 pph)



It's not just how long the runway at the takeoff point is--it's also *how* the aircraft that uses it will be operated. As you can see from these admittedly crude numbers, there's a difference of 21,900 pounds in fuel burn here on the same assumed 3,000nm trip. (Someone can correct me with the actual PVD-LAX and OGG-XYZ distances, but the principle remains unchanged). That same 21,900 punds equates to about 109 passengers and their bags, which might explain why one could operate OGG-XYZ with a full aircraft, but PVD-LAX could only operate full minus 109 folks. Turning the situation around, one could probably operate eastbound PVD-London with no problem, and have problems westbound OGG-Tokyo.

Lot's of other variables involved, such as aircraft type, engine version, runway condition (dry, wet, snow, slush), altimeter setting, and surface winds, but all of these can either help/hurt the situation depending on how the aircraft is planned to be used.

Hope all this makes sense...



User currently offlineILS 15 From , joined Dec 1969, posts, RR:
Reply 3, posted (13 years 11 months 3 weeks 3 days 4 hours ago) and read 1577 times:

I can't answer this for sure but it may have to do w/ competing w/ other airports in the area. Manchester is lengenthing it's 2 runways, 17/35 goes from 7,000 to 9,000ft. and rwy. 6/24 will be 7,000ft. Just throwing this out there,

Greg


User currently offlineJohn From United States of America, joined Sep 1999, 1374 posts, RR: 5
Reply 4, posted (13 years 11 months 3 weeks 3 days ago) and read 1574 times:

OK, So how do they "perform" these miracles from SNA's 5700ft runway, on a daily basis! The fact is, they probably shouldn't be. I know there are special peformance specifications for this airport, so why not other airports? A DCA-LAX route has been proposed recently. The main runway at DCA is only 6870 ft. TWA plans, I believe, to use a 757, subject to the 1250 mile cap being lifted on flights from DCA. If any aircraft can operate from a short runway, it most certainly is the 757! Now let's compare these statistics. Both trips would be about the same, range wise. PVD has a longer runway, though not much longer, at 7166ft. Now tell me why a 757 could not operate nonstop from PVD to the west coast? And a 777 can operate off a 7000ft. runway from OGG-LAX? Hmmmm..somethings not right here.

User currently offlineMlsrar From United States of America, joined Mar 2000, 1417 posts, RR: 8
Reply 5, posted (13 years 11 months 3 weeks 2 days 15 hours ago) and read 1552 times:

John, if you've ever experienced a takeoff at SNA, you might understand. On AA's SNA-ORD leg, the pilot announces on the PA the procedures he uses both for noise abatement, and the short-rwy procedures. It's not a pleasant trip out of SNA. The traffic out of SNA warrants the routes flown. Perhaps PVD hasn't shown the need yet.


I mean, for the right price I’ll fight a lion. - Mike Tyson
User currently offlineBishop1 From , joined Dec 1969, posts, RR:
Reply 6, posted (13 years 11 months 3 weeks 2 days 7 hours ago) and read 1553 times:

Greetings,


Thank you to all of the folks that answered my question.
I have flown in and out of OGG several times and from the flights that I have been on, arriving into OGG they fly through the valley and the departures go out over the water. Could wind have anything to do with it? It does get windy in the afternoon there and they do take off into the wind. The reason I said "assume" the flights are full is that I don't believe that the airlines would start more flights to the islands with larger planes unless it was called for.

As for PVD, I don't believe there are any immediate height restrictions on buildings in the flight path of any of the runways. Mostly goes in/out over commerical and residental areas. The widebodies do use the airport, mostly chartered and business (i.e. UPS).

As for the airport traffic, the facility expanded in 1997, expanded again in 1999 and they are planning another expansion. I believe we will break 5,000,000 this year in service. I think they are projecting 10,000,000 in a few years, that is why for the future expansion.


User currently offlineOPNLguy From , joined Dec 1969, posts, RR:
Reply 7, posted (13 years 11 months 3 weeks 2 days 5 hours ago) and read 1548 times:

Generally speaking, a certain amount of headwind credit in the takeoff weight calculations can help get some extra weight off the ground, but it's not going to erase the 21,900 pound shortfall in my example earlier.

More simply put (hopefully, I've had a long day), Let's assume that a certain type of airliner can takeoff at an absolute maximum of 120,000 lbs., assuming one of those nice 10,000 ft. runways at sea level, on a cool 60F day. (Call this airport-ABC) Take that same aircraft up the road to PVD, and with the same 60F day, PVD's shorter runway only results in a max weight (for PVD's conditions) of 100,000 lbs. This 100,000 lb weight represents the maximum that can be lifted off the ground. and still meet safe/legal performance requirements.

Let's also assume that the aircraft, all by itself without any payload (pax, bags, freight, mail) or fuel onboard, weighs 55,000 lbs. That leaves you with 45,000 lbs of lift capability, yet to be divided between payload and fuel.

If the total fuel load required for the trip PVD-XYZ is 15,000 lbs, you obviously have room for 30,000 lb. of payload. We'll assume that 30,000 lb. payload equates to a full flight.

If we reversed the situation for a longer PVD-LAX that required a minimum fuel load of 30,000 lbs, we then only have 15,000 lbs. of payload, which means you'll only make it non-stop if you take half the folks.

If that same aircraft was able to takeoff from that nearby ABC airport with the 10,000 ft runway, ABC's maximum 120,000 lb takeoff weight ability would enable the aircraft to operate non-stop ABC-LAX with all the fuel, and all the payload, with 5,000 lbs. to spare.

This is just a "simple" example, since there are a number of variables. The 757, and some other aircraft, have some extra muscle, so they probably won't see weight problems anywhere near as often as other types of aircraft. Sometimes, even the same model aircraft can have radically better/worse takeoff weights due to the engine variant installed. I can guarantee you that a 737-200 ADVanced with -17 engines performs better than a 737-200 Basic with -7 engines, even though they *both* look like "identical" 737s to most folks.

Again, it's not just the runway's length, but how one plans to operationally allocate that *available* weight once the aircraft gets airborne. Obviously, PVD's building a longer runway would enable airlines to operate longer distance flights and still be able to take all the folks that want to go.



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