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77west
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Re: Twins vs. quads and international over water routings.

Mon May 29, 2017 6:39 am

sunrisevalley wrote:
sunrisevalley wrote:
I believe the EDTO entry and exit points for this routing is GET or PER -MRU. But this is a long way off the GC track AKL-JNB/CPT The distance from this track to either GET/PER or MRU is substantial. Someone other than I might calculate what these distances might be from various waypoints on the GC track.

I have taken a shot at it based on a EDTO distance of 2396nm from entry/exit points 60min (400nm) from GET and MRU on the GC track between the two The two circles intersect above the AKL-JNB GC track at S61.5 . As I understand it the GC track could not be flown but the difference is negligible. But the 77E and 787 are limited to 302 minutes so that 2396nm is too much and the track would have to be flattened somewhat.
All FWIW......


I thought they had 330 minutes on at least 4 of the 8 77E (NZ)
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zeke
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Re: Twins vs. quads and international over water routings.

Mon May 29, 2017 7:18 am

ETOPS on twins is beyond 60 minutes, quads it's beyond 180 minutes.

What often gets missed is the altitude capability quads have one engine out compared to twins. Going over high terrain may require escape routes for twins to lower terrain where a quad one engine out can continue on.
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sunrisevalley
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Re: Twins vs. quads and international over water routings.

Mon May 29, 2017 6:29 pm

77west wrote:
I thought they had 330 minutes on at least 4 of the 8 77E (NZ)

Since all that is needed is 302 minutes for AKL-EZE this what Boeing had the 77E and 787 certified for. The EDTO sector on this routing is CHC-USH and it is the longest in the world. I believe all 8 of the 77E fleet have flown this sector at least one time. Maybe PA515 has the data on this for each aircraft.
 
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thewizbizman
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Re: Twins vs. quads and international over water routings.

Wed May 31, 2017 5:56 pm

Well, the twin engine jets are working out as Delta Air Lines is getting rid of ALL there B747s by the end of this year (2017).

I'm disappointed about it, but not much I can do about it.

~Zac
"Aviation is the youngest big industry, but it is the fastest growing baby ever. A few years ago, it was called impossible to fly…The day of the airplane is surely here."

April 17, 1929 / C. E. Woolman
 
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c933103
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Re: Twins vs. quads and international over water routings.

Thu Jun 01, 2017 7:51 am

Actually, per http://aviationenglish.club/wp-content/ ... -ETOPS.pdf , although for example the allowed time for ETOPS operation at single engine out speed for 747 is lower, the single engine out speed for 747 is actually higher so that sort of make up the difference, so if according to the pdf which pointed to 747's engine out speed at 1522nm/180mins=507kt then with ETOPS330 and diversion airport of HBA, PLZ, USH (Can these three airports allow landing of 747 and are they ICAO category 7 adequate airport?) then there are no no-go-zone over south pole for 747... but for quads perhaps another element to be consider is the cargo hold fire suppression time, what's the current time provided for 747?

As for twins.. although most remotely possible flight over that small no-go zone in ETOPS 370 over Antarctica can route around that zone with only slight diversion and very minimal increase in flight time due to the great distance those flights would involve, but that zone is apparently possible to be completely being do away by allowing extra 30 minutes on top of it or making an airport there.... while there are no way such thing would happen now as there are no flight flying a route remotely close to that, it will probably happen if somehow the sky over Antarctica become as busy as nowadays TATL or TPAC routes....
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timz
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Re: Twins vs. quads and international over water routings.

Fri Jun 02, 2017 9:21 pm

77west wrote:
[CPT-AKL] will take a significant detour or increase in EDTO

Offhand guess: the detour increases total distance by less than 10%.
 
timz
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Re: Twins vs. quads and international over water routings.

Sat Jun 03, 2017 3:27 am

If 330 minutes equals 2200 nm, then the turning point south of MRU and PER is 54.65744S 75.1210E and total distance is 6589.4 nm instead of 6355.5 on the direct route.
 
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77west
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Re: Twins vs. quads and international over water routings.

Sun Jun 04, 2017 10:23 pm

timz wrote:
77west wrote:
[CPT-AKL] will take a significant detour or increase in EDTO

Offhand guess: the detour increases total distance by less than 10%.


I just ran it through a flight planner and got less than 7% actually. The great circle mapper must be off or I misinterpreted the shaded areas.

This was using FACT, FIMP, YPPH and NZCH as EDTO diversion airports. So do-able at 330mins.

Image
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c933103
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Re: Twins vs. quads and international over water routings.

Thu Jun 08, 2017 7:00 am

77west wrote:
timz wrote:
77west wrote:
[CPT-AKL] will take a significant detour or increase in EDTO

Offhand guess: the detour increases total distance by less than 10%.


I just ran it through a flight planner and got less than 7% actually. The great circle mapper must be off or I misinterpreted the shaded areas.

This was using FACT, FIMP, YPPH and NZCH as EDTO diversion airports. So do-able at 330mins.

It actually match the gcmap shades, as you can see the point farthest away is more than 10 degree in latitude norther than the the gc route. But the distance increase is rather small because the flight is quite long so the impact is spread out.
Now I am wondering, because of the wind direction, it's probably faster for a return flight AKL-CPTto fly through Southern Chilean Airspace instead.. Could you plot that path out too?
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77west
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Re: Twins vs. quads and international over water routings.

Thu Jun 08, 2017 8:10 am

c933103 wrote:
77west wrote:
timz wrote:
Offhand guess: the detour increases total distance by less than 10%.


I just ran it through a flight planner and got less than 7% actually. The great circle mapper must be off or I misinterpreted the shaded areas.

This was using FACT, FIMP, YPPH and NZCH as EDTO diversion airports. So do-able at 330mins.

It actually match the gcmap shades, as you can see the point farthest away is more than 10 degree in latitude norther than the the gc route. But the distance increase is rather small because the flight is quite long so the impact is spread out.
Now I am wondering, because of the wind direction, it's probably faster for a return flight AKL-CPTto fly through Southern Chilean Airspace instead.. Could you plot that path out too?


Just ran a quick and dirty plot, and crossing Chile it came back at over 8,000nm so no, even taking winds into account I don't think that would work. You are talking about crossing both the pacific and atlantic oceans. Using 80S70W which is the furthest south I could select, it comes back at 6,870nmm which is better, BUT I am not sure how helpful the winds would be. See below, ETOPS 330 using NZCH/SCCI and SCCI/FACT. I included the wind overlay out of interest.
Image
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77west
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Re: Twins vs. quads and international over water routings.

Thu Jun 08, 2017 9:51 am

77west wrote:
c933103 wrote:
77west wrote:

I just ran it through a flight planner and got less than 7% actually. The great circle mapper must be off or I misinterpreted the shaded areas.

This was using FACT, FIMP, YPPH and NZCH as EDTO diversion airports. So do-able at 330mins.

It actually match the gcmap shades, as you can see the point farthest away is more than 10 degree in latitude norther than the the gc route. But the distance increase is rather small because the flight is quite long so the impact is spread out.
Now I am wondering, because of the wind direction, it's probably faster for a return flight AKL-CPTto fly through Southern Chilean Airspace instead.. Could you plot that path out too?


Just ran a quick and dirty plot, and crossing Chile it came back at over 8,000nm so no, even taking winds into account I don't think that would work. You are talking about crossing both the pacific and atlantic oceans. Using 80S70W which is the furthest south I could select, it comes back at 6,870nmm which is better, BUT I am not sure how helpful the winds would be. See below, ETOPS 330 using NZCH/SCCI and SCCI/FACT. I included the wind overlay out of interest.
Image


EDIT: The winds help during the first couple of hours and the last couple of hours; but the main bulk of the flight, the winds are a bit wishy-washy in terms of groundspeed.
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c933103
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Re: Twins vs. quads and international over water routings.

Thu Jun 08, 2017 12:46 pm

77west wrote:
Just ran a quick and dirty plot, and crossing Chile it came back at over 8,000nm so no, even taking winds into account I don't think that would work. You are talking about crossing both the pacific and atlantic oceans. Using 80S70W which is the furthest south I could select, it comes back at 6,870nmm which is better, BUT I am not sure how helpful the winds would be. See below, ETOPS 330 using NZCH/SCCI and SCCI/FACT. I included the wind overlay out of interest.

EDIT: The winds help during the first couple of hours and the last couple of hours; but the main bulk of the flight, the winds are a bit wishy-washy in terms of groundspeed.

Even just considering the couple of hours after departure and before arrival, it seems to be still better than the couple of hours head on wind in the other route, when the difference in distance is just about a hundred or so nm
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77west
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Re: Twins vs. quads and international over water routings.

Fri Jun 09, 2017 5:42 am

c933103 wrote:
77west wrote:
Just ran a quick and dirty plot, and crossing Chile it came back at over 8,000nm so no, even taking winds into account I don't think that would work. You are talking about crossing both the pacific and atlantic oceans. Using 80S70W which is the furthest south I could select, it comes back at 6,870nmm which is better, BUT I am not sure how helpful the winds would be. See below, ETOPS 330 using NZCH/SCCI and SCCI/FACT. I included the wind overlay out of interest.

EDIT: The winds help during the first couple of hours and the last couple of hours; but the main bulk of the flight, the winds are a bit wishy-washy in terms of groundspeed.

Even just considering the couple of hours after departure and before arrival, it seems to be still better than the couple of hours head on wind in the other route, when the difference in distance is just about a hundred or so nm


Fair point. But Chile is not gonna work, too far off the GC route. So they fly in one direction only, are there any other routes that do this?
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c933103
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Re: Twins vs. quads and international over water routings.

Fri Jun 09, 2017 10:56 am

77west wrote:
c933103 wrote:
77west wrote:
Just ran a quick and dirty plot, and crossing Chile it came back at over 8,000nm so no, even taking winds into account I don't think that would work. You are talking about crossing both the pacific and atlantic oceans. Using 80S70W which is the furthest south I could select, it comes back at 6,870nmm which is better, BUT I am not sure how helpful the winds would be. See below, ETOPS 330 using NZCH/SCCI and SCCI/FACT. I included the wind overlay out of interest.

EDIT: The winds help during the first couple of hours and the last couple of hours; but the main bulk of the flight, the winds are a bit wishy-washy in terms of groundspeed.

Even just considering the couple of hours after departure and before arrival, it seems to be still better than the couple of hours head on wind in the other route, when the difference in distance is just about a hundred or so nm


Fair point. But Chile is not gonna work, too far off the GC route. So they fly in one direction only, are there any other routes that do this?

An example I can think of would be Air India's DEL-SFO-DEL flight, the AI173 flight to SFO passes through China and Pacific, whereas the return flight to AI174 passes through Canada, Greenland, and Russia
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rcair1
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Re: Twins vs. quads and international over water routings.

Tue Jun 13, 2017 6:33 pm

PatrickZ80 wrote:
BEG2IAH wrote:
What if they do lose one engine on take off, i.e., at V1? Aren't twins certified to take off on one engine? I'm not talking about starting a take off roll on one engine, that would be insanity. I'm talking V1 speeds. Thanks.


I guess so, but in that case the length or route of the flight wouldn't matter either. A take off is a take off, regardless if it's a long flight or a short hop.

Yes, twins must be able to continue takeoff after V1 with a single engine. That is why the engine on a Twin is so much bigger than is required for cruise.
rcair1
 
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Starlionblue
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Re: Twins vs. quads and international over water routings.

Wed Jun 14, 2017 12:12 am

rcair1 wrote:
PatrickZ80 wrote:
BEG2IAH wrote:
What if they do lose one engine on take off, i.e., at V1? Aren't twins certified to take off on one engine? I'm not talking about starting a take off roll on one engine, that would be insanity. I'm talking V1 speeds. Thanks.


I guess so, but in that case the length or route of the flight wouldn't matter either. A take off is a take off, regardless if it's a long flight or a short hop.

Yes, twins must be able to continue takeoff after V1 with a single engine. That is why the engine on a Twin is so much bigger than is required for cruise.


The engines aren't actually bigger than what is required in the cruise. In the cruise, they are sitting at around 90% of maximum thrust.

This is why if we lose an engine near the top of the altitude envelope we have to descend a good 15000 feet at least to have a chance of maintaining altitude.
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