Rick767 From United Kingdom, joined Jan 2000, 2662 posts, RR: 52 Reply 2, posted (10 years 1 month 3 weeks 1 day 19 hours ago) and read 6647 times:
Non-stop is far more efficient. Like you said, consideration has to be made not only to additional fuel used (which is very high for each take-off and climbout) but also landing and parking fees and other airport handling charges during the transit stop.
At peak times in the UK for example, aircraft are charged for occupying the terminal stand per 7.5 minutes (cost varies with aircraft weight, but it's hundreds of pounds per 7.5 minutes for a 767).
The transit costs alone would probably far outweigh the extra fuel used in the early stages of the non-stop flight, when as you correctly say the aircraft is heavy and burns more fuel flying at a lower level.
If the aircraft has the range (with the desired payload onboard!) then non-stop is always preferable.
I used to love the smell of Jet-A in the morning...
Laxintl From United States of America, joined May 2000, 23466 posts, RR: 50 Reply 4, posted (10 years 1 month 3 weeks 1 day 2 hours ago) and read 6528 times:
Depends on how you define efficient.
It could very well be that a stop between two points is required simply from a marketing or operational point of view.
Here are two examples.
An airline wants to fly between point A and point B. However the traffic total (passenger or cargo) does not warrant the nonstop service on a profitable stand alone basis. However by adding a stop in city C which is located between at city A and B, the airline can capitalise on traffic between, city A-C, A-B and B-C. In otherwords be able to sell each leg to fill a flight that would not work on its own between city A-B.
Another example is that the A-B city is close to the operational limit of an aircraft. By operting nonstop, lets say, the airline is limited in the amount of passengers or cargo it can carry due to weight limitations. By adding a stop, between the two point the, carrier can maximize the payload it can uplift. The added stop can be a pure technical landing for fuel only, or can be a commercial stop as the above example. There are many airport that capitalise on the need of airlines for such fuel stops. A few of the top of my head are Gander Canada and Bangor Maine which are often used by airlines as technical stops operating across the Atlantic.
From the desert to the sea, to all of Southern California
B747skipper From , joined Dec 1969, posts, RR: Reply 5, posted (10 years 1 month 2 weeks 3 days 17 hours ago) and read 6392 times:
To give you a complete answer - there are two considerations...
(1) Operating the airplane for a flight, non-stop, carrying a payload but having to carry a lot of fuel, thereby reducing the payload that can be carried.
(2) Operating the airplane for a flight with 1 tech-stop (to refuel) and operating this aircraft with its maximum payload (limited by the MZFW maximum zero fuel weight) and flying it with less fuel because of that heavy payload...
Generally speaking, for various reasons, in passenger operations, the option "(1)" is better - passengers are attracted by non-stop flights... for cargo operations, I would recommend option "(2)" as the payload increase bring much higher revenue differential.
I only have 747-200/300 "numbers" in my head, in pratical situation, a passenger 200 can operate 12 hours-long sectors with acceptable passenger loads, while such airplanes in cargo configuration, flights with maximum cargo payloads can be operated on flights up to 7 hours long...
Example: Buenos Aires to Madrid, non-stop passenger flight, compared to Buenos Aires to other European destinations, for a cargo aircraft, with a fuel stop in Sal, Cabo Verde Islands... With some cargo airplanes which are not capable of high takeoff weights (i.e. some passenger 747s converted as cargo airplanes), a 2-stop may be required, i.e. tech stops in Recife, Brazil, and Las Palmas, Canarias...
Landing and handling fees, fuel costs, extra crews for longer duty, need to be factored in as well... In this day and age of computer flight planning, planning for maximum revenue or minimum operating costs can be obtained by dispatchers... For planning purpose, we assume that "each passenger" carried is 100 kg average (passenger weight + baggage weight) on long flights. For cargo, obviously, we use actual weights for planning purpose and to derive a "maximum payload available" on certain sectors.
Realize also that number of flights (often the case of passenger flights) we operate with a "redispatch-rerelease" on the way to destination... i.e. on a Buenos Aires to Madrid flight, we initially use a point short of Las Palmas to decide to rerelease and continue to Madrid, provided that Madrid weather is good, and the aircraft still has sufficient fuel at that point, to continue to Madrid, or land in Las Palmas... This permits to increase the payload available by some 5 to 10,000 kg...
Last year, we only had 2 flights that were required to land and refuel in LPA, just because their fuel was marginal to continue to MAD...
S.p.a.s. From Liechtenstein, joined Mar 2001, 957 posts, RR: 3 Reply 6, posted (10 years 1 month 2 weeks 3 days 17 hours ago) and read 6374 times:
On my swissair dispatch days at GRU I used reclearence very often specially as both stations (EZE and SCL) had very good cargo loadings(normally perishables), and so was our case, and during the summer, STD 1405LT and at 2500ft, I had to use all available trick to get the necessary weight.... more than often my loadsheets (I was also responsible for the w/b) came out with underload zero...
The usual PR was over south France using Nice and Marseille, or Toulouse, sometimes Palma de Mallorca or even Barcelona... we had a two hours out rule of thumb...
Btw, when can I expect you here at GRU for a coffee and some nice chat about "don Diego, Boca, etc etc"
B747skipper From , joined Dec 1969, posts, RR: Reply 7, posted (10 years 1 month 2 weeks 3 days 16 hours ago) and read 6371 times:
Oi Renato -
Always a pleasure to read your lines from Brasil...
You and I know that airlines select airplanes by "how far can they carry a maximum payload" rather than maximum range... with ping-pong balls as a payload... The maximum range of airplanes imposes so drastic payload restrictions...
When you see these brochures from Boeing or Airbus, they always stress how far that airplane can fly... with min payload... what a hoax. People who select airplanes look at other numbers as you know...
I take this opportunity to give a salute to Brasil's aviation industry, while both your country and mine have airlines in bad financial shape, Brasil has acquired an outstanding reputation, with Varig, TAM and... Embraer...
At GRU, we stay at Hotel Deville near the airport, who knows we will meet one day there, and as a matter of fact I own a little beach house near Florianopolis SC... love it there, I plan to retire permanently in Floriapo in 5 years and enjoy Caxacas... e podo falar portugues bem, meu esposa tambem. But I have to learn dancar samba, so far I only do tango...
I hope you dont mind, but I dont like Boca, I am for River... "My team" in Brasil is Gremio... because of my wife, she has relatives in Porto Alegre RS... Hope we dont have to meet on the next "Mundial"... if Brasil has a game against Argentina... I might not speak to you...
S.p.a.s. From Liechtenstein, joined Mar 2001, 957 posts, RR: 3 Reply 8, posted (10 years 1 month 2 weeks 3 days 11 hours ago) and read 6338 times:
Amazing! So you are also a Florianopolis addicted? I have no house there yet, but would live there without even thinking about it.... Wonderful place.. I'm always there during the summer, visiting some friends...(not to mention las chicas )
About football, I'm not very into the game so no worries at all.. but living for almost a decade in BAires you probably know about Argentina x Brazil arguments on it ...
Bruce From United States of America, joined May 1999, 5034 posts, RR: 17 Reply 9, posted (10 years 1 month 2 weeks 2 days 21 hours ago) and read 6281 times:
Well I guess that would explain all the cargo stops/refuelings at Anchorage for flights from far east to USA, while passenger planes do it every day non stop such as Northwest from Detroit or MSP. I think you can fly from JFK to say China or Japan non stop in pax config but cargo will stop many times. Makes sense that cargo planes fly heavier.
Bruce Leibowitz - Jackson, MS (KJAN) - Canon 50D/100-400L IS lens
Cloudy From , joined Dec 1969, posts, RR: Reply 11, posted (10 years 1 month 1 week 5 days 6 hours ago) and read 6138 times:
I thought that runway length and conditions also influence the payload/range curve. That is, to get a number for the "Range with Maximum Payload" - you need to assume a number for runway length, temp., and airport altitude as well.
Even "MaxPayloadRange" may not be good enough for comparison shopping unless this range cannot be reached (at least the vast majority of the time) from the airports an airline operates from.
If you compare the 757 and 767 freighters......my guess is the 767 may carry more cargo further when runway length and weather is not an issue, but if you are flying to a "hot and high" airport or an airport with shorter runways the 757 may be better. One of the reason the 757 is used often where one might expect to see either widebodies or the 737 is because of that type's great takeoff performance.
I suspect that what airlines do when aquiring aircraft is pick a large number of routes they plan to fly a new aircraft type. Then they plug in the performance numbers for each candidate considering everything - runway length, climate, aircraft performance, etc. Only when you see customized, route specific performance numbers can a real comparison be made.
I guess when you are talking about aircraft like the 747 - MaxPayloadRange assumes a runway length that would be adequate for most major international airports in most conditions. So it may serve for rough comparisons.