747 vs 777 HAMI route
Thread Starter
Join Date: May 2009
Location: netherlands
Age: 38
Posts: 7
Likes: 0
Received 0 Likes
on
0 Posts
747 vs 777 HAMI route
I was wondering why airliners use a B777-200ER for flights from MNL to AMS. This is an ETOPS flight on the HAMI route which makes it " dangerous" flight if one engine fails. Why won't they use a B747-400 instead? It has 4 engines a higher capacity, sure its less fuel efficient but doesnt they payload cover it enough?
Or is the 747 restricted due to N-1 or N-2 (i have no clue which situation they must plan for) at DP2 (Near DOREX) in the himalaya?
I know the 777-200ER is restricted due to the DP2 on the Hami route.
Im looking forward to all the suggestions/answers
Or is the 747 restricted due to N-1 or N-2 (i have no clue which situation they must plan for) at DP2 (Near DOREX) in the himalaya?
I know the 777-200ER is restricted due to the DP2 on the Hami route.
Im looking forward to all the suggestions/answers
Join Date: Jun 2001
Location: UTC +8
Posts: 2,626
Likes: 0
Received 0 Likes
on
0 Posts
The highest peak of the Tian Shan mountain range tops only at 24,500' and the route is neither critical nor "dangerous" for a B744, which upon reaching the sector between REVKI and KCA [highest MEA], will already have burned enough fuel to easily maintain FL315 [9,600m] on 3 engines.
I'm not familiar with B772 single engine performance, but the higher peaks of this mountain range [which is not part of the Himalayas] is fairly narrow. In case of an ETOPS engine failure, an immediate turn off the airway to lower terrain could be achieved within 10 minutes during gradual "driftdown" [opeartated at MCT on the remaining engine]. Keep in mind that airplanes originating at MNL, HKG, PVG or PEK will already have burned off several hours fuel before reaching these peaks, so the airplane would not be struggling at max gross weight with an inoperative engine. And if maintaining sufficient engine-out altitude were a problem, then fuel could be dumped immediately and the airplane could be diverted to a designated ETOPS en route alternate airport.
I'm not familiar with B772 single engine performance, but the higher peaks of this mountain range [which is not part of the Himalayas] is fairly narrow. In case of an ETOPS engine failure, an immediate turn off the airway to lower terrain could be achieved within 10 minutes during gradual "driftdown" [opeartated at MCT on the remaining engine]. Keep in mind that airplanes originating at MNL, HKG, PVG or PEK will already have burned off several hours fuel before reaching these peaks, so the airplane would not be struggling at max gross weight with an inoperative engine. And if maintaining sufficient engine-out altitude were a problem, then fuel could be dumped immediately and the airplane could be diverted to a designated ETOPS en route alternate airport.
Thread Starter
Join Date: May 2009
Location: netherlands
Age: 38
Posts: 7
Likes: 0
Received 0 Likes
on
0 Posts
Hey Glueball Thanks for your reply! The thing is the highest peak might be near Revki which is called DP1 (decision point) but when flying from MNL you will have a larger gross weight at DP2 (DOREX) with a MEA of 17500. So dp2 is more critical then the revki point due to the fuel burn that youve explained.
I have a flight planning and performance manual from KLM about the B772 and the maximum gross weight at that point is 256000kg. Sadly i dont have a manual for the B744 to compare it with.
My question is: Why do airlines use a B772 for the HAMI route when a 744 can carry way more? (flightplanning occurs for 50% of engine loss so an N-2 for the B744) Is the B744 weight restricted at the same point as the B772?
I have a flight planning and performance manual from KLM about the B772 and the maximum gross weight at that point is 256000kg. Sadly i dont have a manual for the B744 to compare it with.
My question is: Why do airlines use a B772 for the HAMI route when a 744 can carry way more? (flightplanning occurs for 50% of engine loss so an N-2 for the B744) Is the B744 weight restricted at the same point as the B772?
Join Date: Jun 2001
Location: UTC +8
Posts: 2,626
Likes: 0
Received 0 Likes
on
0 Posts
Not every airline has B744s, and otherwise B777s might be justified for the traffic load. In any case, I doubt that the overpowered B772 would have a problem maintaining MEA of FL175 at DOREX with one engine inoperative. Perhaps a B777 driver can tell you the engine-out max FL at max gross weight.
Join Date: Jul 2002
Location: London
Posts: 171
Likes: 0
Received 0 Likes
on
0 Posts
Took off out of SIN recently on one of our 772's at 285T, and the ENG OUT altitude when we reached ToC was FL175.
On routes over high terrain where you may be struggling to maintain MSA on one engine, or after a decompression, then we have escape routes published for that very reason.
On routes over high terrain where you may be struggling to maintain MSA on one engine, or after a decompression, then we have escape routes published for that very reason.
Thread Starter
Join Date: May 2009
Location: netherlands
Age: 38
Posts: 7
Likes: 0
Received 0 Likes
on
0 Posts
Heh ye KLM gave out an A/D few years ago that the MTOM departing from Chengdu (near Dorex) was 285T
Anyone have experiences planning a flight for a B744? Id like to know the advantages/disadvantages between those two.
Anyone have experiences planning a flight for a B744? Id like to know the advantages/disadvantages between those two.
Join Date: Jun 2004
Location: Australia
Posts: 1,843
Likes: 0
Received 0 Likes
on
0 Posts
From a lot of the foregoing it seems that few are concerned with the depressurisation case, which applies if your aircraft has 2 or 10 engines.
Those operators who consider F/L315 a safe operation where the terrain reaches 24,500 feet must be carrying a prodigious amount of passenger oxygen, or are these aircraft depressurisation-proof?
Regards,
Old Smokey
Those operators who consider F/L315 a safe operation where the terrain reaches 24,500 feet must be carrying a prodigious amount of passenger oxygen, or are these aircraft depressurisation-proof?
Regards,
Old Smokey
Join Date: Oct 2007
Location: sh!# hole
Posts: 175
Likes: 0
Received 0 Likes
on
0 Posts
Well we fly our B777-300ERs over the Himalayas where the safety height is around 28 000ft. I wouldn't call it dangerous but you got to know where (direction) you are going to go if an engine fails.
Thread Starter
Join Date: May 2009
Location: netherlands
Age: 38
Posts: 7
Likes: 0
Received 0 Likes
on
0 Posts
Its still weird though... ETOPS was designed to being able to travel over oceans... and now its being used in mountanious areas where you are drift down limited (oxygen supply can easily be expanded) When flying 1200nm with N-1 on a B777 and drifiting down... seems impossible to me
Join Date: Aug 2000
Location: EU
Posts: 262
Likes: 0
Received 0 Likes
on
0 Posts
Lars, you assumptions is curious. There are special procedures in place to deal with contingencies. Some deal with an N-1 situation, others deal with decompression (these are specifically designed to not run out of passenger oxygen). It is the raison d’etre for the HAMI route. The more direct routing for many of the flights being mentioned is L888, this posses such severe restrictions mostly due to insufficient oxygen for the passengers that at my airline we can only plan freighter aircraft along this route. The oxygen for crew is more than sufficient.
You last posts mentions that ETOPS was designed to be able to fly across oceans. It was not, it was an instrument to allow twin engined aircraft to operate more than 60 minutes flying time (in still air conditions) from an adequate aerodrome. It is true that it allowed twin engine aircraft to operate across the oceans, and was one of the drivers behind ETOPS. Maybe do a search on LROPS, both the Europeans and Americans are looking into this issue, and it will apply to any aircraft flying Long range operations, regardless of engine numbers.
As for a 1200 NM diversion on one engine, this is a highly unlikely scenario. At any point along the HAMI route there are enough alternates. Ranging from Astana, Almaty, and Urumqi on the west side, to Irkutsk, Lanzhou, Beijing, Xian, or Chengdu on the eastern side.
With a maximum take-off weight of around 297,500 kilograms on the Boeing 772ER (not unusual out of MNL) the restriction at DP2 of 285,000 kilograms is not a punitive restriction (enough fuel has been burned off by then). At least I have never seen it impact the planning for this flight.
You first question on why an airline would use a B772ER on a flight like MNL to AMS, the answer couldn’t be easier. It is the equipment that maximizes the revenue. MNL to AMS is a pretty tough stretch for a B747-400. My personal record on this flight is 14.15 hours. With these kinds of flight times the maximum payload on the 747 would be constrained. In other words; you would have to substitute fuel for payload. On a Boeing 777-300ER (also operating on this route on certain days) which carries one passenger less than the Boeing 747-400 at the airline we are talking about, the fuel burn difference is in the range of 25-30% between the two. Since 2/3 of all costs associated with our flight operations (in the order of two billion Euros, annually) concerns fuel you can imagine the cost advantages of using a Boeing 777-300ER over the Boeing 747-400.
Lastly oxygen supply cannot be easily expanded. It is not needed, as all contingency procedures cover this eventuality. Fitting bigger, or more oxygen bottles (both in use on the 747 and 777) would make both aircrafts empty weight a lot higher. You will haul this weight around on every flight (burning up expensive fuel). You will do this in order to service one route that we fly. Maybe this raises the question for you, why don’t they just use one airplane for this route with bigger bottles? Here you run into an issue that each airline has that operates these kind of sectors. In order to maintain a daily flight on this route you need at least two aircraft, since the cycle for a return flight is on the order of 28 hours. So by the time the aircraft would return to its home base the next daily flight will already have left. This means this aircraft will fly more and different (often shorter cycles) to be ready for its next long haul flight. Inherently meaning you are burning up expensive fuel hauling around these oxygen bottles on sectors where they aren’t needed.
I am very much on the inside at the airline we are talking about, and I can tell you that some very creative and smart people are always looking into all facets associated for maximizing cost/benefit. The Boeing 747 is in its last years with this airline (likely start of the phase out will be 2013/14). You are unlikely to see any new passenger aircraft with more than two engines at this airline, I am certainly not hearing of anything beyond 787’s or A350 or combination thereof. I hope I have answered some of your questions.
You last posts mentions that ETOPS was designed to be able to fly across oceans. It was not, it was an instrument to allow twin engined aircraft to operate more than 60 minutes flying time (in still air conditions) from an adequate aerodrome. It is true that it allowed twin engine aircraft to operate across the oceans, and was one of the drivers behind ETOPS. Maybe do a search on LROPS, both the Europeans and Americans are looking into this issue, and it will apply to any aircraft flying Long range operations, regardless of engine numbers.
As for a 1200 NM diversion on one engine, this is a highly unlikely scenario. At any point along the HAMI route there are enough alternates. Ranging from Astana, Almaty, and Urumqi on the west side, to Irkutsk, Lanzhou, Beijing, Xian, or Chengdu on the eastern side.
With a maximum take-off weight of around 297,500 kilograms on the Boeing 772ER (not unusual out of MNL) the restriction at DP2 of 285,000 kilograms is not a punitive restriction (enough fuel has been burned off by then). At least I have never seen it impact the planning for this flight.
You first question on why an airline would use a B772ER on a flight like MNL to AMS, the answer couldn’t be easier. It is the equipment that maximizes the revenue. MNL to AMS is a pretty tough stretch for a B747-400. My personal record on this flight is 14.15 hours. With these kinds of flight times the maximum payload on the 747 would be constrained. In other words; you would have to substitute fuel for payload. On a Boeing 777-300ER (also operating on this route on certain days) which carries one passenger less than the Boeing 747-400 at the airline we are talking about, the fuel burn difference is in the range of 25-30% between the two. Since 2/3 of all costs associated with our flight operations (in the order of two billion Euros, annually) concerns fuel you can imagine the cost advantages of using a Boeing 777-300ER over the Boeing 747-400.
Lastly oxygen supply cannot be easily expanded. It is not needed, as all contingency procedures cover this eventuality. Fitting bigger, or more oxygen bottles (both in use on the 747 and 777) would make both aircrafts empty weight a lot higher. You will haul this weight around on every flight (burning up expensive fuel). You will do this in order to service one route that we fly. Maybe this raises the question for you, why don’t they just use one airplane for this route with bigger bottles? Here you run into an issue that each airline has that operates these kind of sectors. In order to maintain a daily flight on this route you need at least two aircraft, since the cycle for a return flight is on the order of 28 hours. So by the time the aircraft would return to its home base the next daily flight will already have left. This means this aircraft will fly more and different (often shorter cycles) to be ready for its next long haul flight. Inherently meaning you are burning up expensive fuel hauling around these oxygen bottles on sectors where they aren’t needed.
I am very much on the inside at the airline we are talking about, and I can tell you that some very creative and smart people are always looking into all facets associated for maximizing cost/benefit. The Boeing 747 is in its last years with this airline (likely start of the phase out will be 2013/14). You are unlikely to see any new passenger aircraft with more than two engines at this airline, I am certainly not hearing of anything beyond 787’s or A350 or combination thereof. I hope I have answered some of your questions.
Thread Starter
Join Date: May 2009
Location: netherlands
Age: 38
Posts: 7
Likes: 0
Received 0 Likes
on
0 Posts
Wow Otterman, your answer is just BRILLIANT Thanks for enlighting me! The reason i was asking all these questions is since I'm doing a project which involved flightplanning a B772ER from MNL to AMS. And the questions arrose why one wouldnt use a 747! I still need to do a presentation about it and im sure ill use some of your answers in it .
Thanks again.
Ps,
Do you know why it burns more fuel? Poorly designed? Less fuel efficient engines?
Thanks for enlighting me! The reason i was asking all these questions is since I'm doing a project which involved flightplanning a B772ER from MNL to AMS. And the questions arrose why one wouldnt use a 747! I still need to do a presentation about it and im sure ill use some of your answers in it .Thanks again.
Ps,
Do you know why it burns more fuel? Poorly designed? Less fuel efficient engines?
Join Date: Aug 2000
Location: EU
Posts: 262
Likes: 0
Received 0 Likes
on
0 Posts
There is a lot of time between both designs. The B747 is a fantastic aircraft (I have flown close to 10,000 hours on the classic version).
The Boeing 747 was originally designed for a competition to supply the US armed forces with a large transport aircraft. It lost this competition to the Lockheed C-5 Galaxy. Pan Am placed an order for 25 B747’s and Boeing took a large gamble to further develop the B747. This is all back in the late 1960’s. Although the Boeing 747-400 is a much more efficient version of the original design the basic airframe dates from that time. The Boeing 747-400 is much more efficient than the Boeing 747-200 and 300’s it replaced. Also on the order of 20%. On top of this it reduced cockpit crewing costs because it eliminated the flight engineering position.
The Boeing 777 design date to the early 1990’s. ETOPS was a well established concept, and the resistance that a lot of airlines initially had to flying long haul flights with less than three engines had eased off. This is the case for my airline as well. Even back in the late 1980’s our (then) CEO stated that we would never fly across the ocean on less than three engines. Now it is not even an issue.
The original Boeing 777-200 was nicely slotted in between the Boeing 767 and the Boeing 747-400. So each aircraft served its own niche. But the design of the original Boeing 777 allowed the aircraft to be stretched into the segment served by the Boeing 747-400. All that was required was a very high thrust engine. This challenge was taken up by General Electric with the development of the GE90-115. On the version of the Boeing 747 (-300) I flew each engine produced 52,000 pounds of thrust. The GE-90-115 produces 115,000 pounds of thrust. This new version of the 777 became the Boeing 777-300. A direct competitor for the passenger version of the Boeing 747-400. If an airline already operates the 747 it requires very large capital expenditures to replace them with Boeing 777-300’s. When the fuel prices started to rise the equations started to tilt in favor of this replacement, and that is what you are seeing. Air France is getting rid of their Boeing 747-400 passenger fleet, replacing them with the Boeing 777-300ER (and some A380’s). KLM is taking the first steps in this process, British Airways has also started ordering the aircraft, and in the ultra large capacity segment has ordered the A380. All this will likely mean the end of the Boeing 747 passenger version.
As you know Boeing is in the process of making a new version of the Boeing 747(-8). It only has one significant customer for the passenger version (Lufthansa), it is likely only to see service as a freighter (a role for which it is well suited). But at the moment the cargo market is in a world of hurt, and certainly my airline is not looking for this aircraft.
So, the short of it is that the Boeing 747-400 is most certainly not a bad design. But technology and operating economics (read the huge increase in fuel costs) have changed the playing field in favor of the Boeing 777-300ER for the passenger carrying business.
In my time in the airline business fuel costs have increased from 1/3 of our operational budget to 2/3 of our operational budget (in pure numbers this means a change of one billion Euros).
A shocking number to everyone who reads it for the first time is that as of the end of 2007, the airline business collectively broke even from the time we started to carry passengers/freight/and mail to the end of 2007. That is right not a single Euro/Dollar/Yen was made, in our collective business. The profits made by some, were offset by the huge losses and bankruptcies made by others. This business is extremely silly. Yet “we” were able to make it the safest method of transport over long distances. The losses made by almost everyone since the end of 2007 has only exacerbated this situation.
The Boeing 747 was originally designed for a competition to supply the US armed forces with a large transport aircraft. It lost this competition to the Lockheed C-5 Galaxy. Pan Am placed an order for 25 B747’s and Boeing took a large gamble to further develop the B747. This is all back in the late 1960’s. Although the Boeing 747-400 is a much more efficient version of the original design the basic airframe dates from that time. The Boeing 747-400 is much more efficient than the Boeing 747-200 and 300’s it replaced. Also on the order of 20%. On top of this it reduced cockpit crewing costs because it eliminated the flight engineering position.
The Boeing 777 design date to the early 1990’s. ETOPS was a well established concept, and the resistance that a lot of airlines initially had to flying long haul flights with less than three engines had eased off. This is the case for my airline as well. Even back in the late 1980’s our (then) CEO stated that we would never fly across the ocean on less than three engines. Now it is not even an issue.
The original Boeing 777-200 was nicely slotted in between the Boeing 767 and the Boeing 747-400. So each aircraft served its own niche. But the design of the original Boeing 777 allowed the aircraft to be stretched into the segment served by the Boeing 747-400. All that was required was a very high thrust engine. This challenge was taken up by General Electric with the development of the GE90-115. On the version of the Boeing 747 (-300) I flew each engine produced 52,000 pounds of thrust. The GE-90-115 produces 115,000 pounds of thrust. This new version of the 777 became the Boeing 777-300. A direct competitor for the passenger version of the Boeing 747-400. If an airline already operates the 747 it requires very large capital expenditures to replace them with Boeing 777-300’s. When the fuel prices started to rise the equations started to tilt in favor of this replacement, and that is what you are seeing. Air France is getting rid of their Boeing 747-400 passenger fleet, replacing them with the Boeing 777-300ER (and some A380’s). KLM is taking the first steps in this process, British Airways has also started ordering the aircraft, and in the ultra large capacity segment has ordered the A380. All this will likely mean the end of the Boeing 747 passenger version.
As you know Boeing is in the process of making a new version of the Boeing 747(-8). It only has one significant customer for the passenger version (Lufthansa), it is likely only to see service as a freighter (a role for which it is well suited). But at the moment the cargo market is in a world of hurt, and certainly my airline is not looking for this aircraft.
So, the short of it is that the Boeing 747-400 is most certainly not a bad design. But technology and operating economics (read the huge increase in fuel costs) have changed the playing field in favor of the Boeing 777-300ER for the passenger carrying business.
In my time in the airline business fuel costs have increased from 1/3 of our operational budget to 2/3 of our operational budget (in pure numbers this means a change of one billion Euros).
A shocking number to everyone who reads it for the first time is that as of the end of 2007, the airline business collectively broke even from the time we started to carry passengers/freight/and mail to the end of 2007. That is right not a single Euro/Dollar/Yen was made, in our collective business. The profits made by some, were offset by the huge losses and bankruptcies made by others. This business is extremely silly. Yet “we” were able to make it the safest method of transport over long distances. The losses made by almost everyone since the end of 2007 has only exacerbated this situation.
Join Date: Jun 2001
Location: UTC +8
Posts: 2,626
Likes: 0
Received 0 Likes
on
0 Posts
Old Smokey
You are somewhat missing the point. If you go to Google-Earth and run the curser over the terrain from HKG-PVG-PEK-URC [Urumqi] -KCA - REVKI . . . you will discover that there is plenty lower terrain adjacent to the airway, and adjacent to the Tian Shan mountain range. So, if you have a pressurization problem, there is no need to stay on the airway and to maintain FL310 for long. You would turn off the airway to lower terrain and land at a designated en route alternate/contingency airport. For example, Urumqi airport has an 11,800' [3600m] pavement at an elevation of only 2150' MSL.
Those operators who consider F/L315 a safe operation where the terrain reaches 24,500 feet must be carrying a prodigious amount of passenger oxygen, or are these aircraft depressurisation-proof?
