ETOPS Rules
#1
Posted 20 August 2010 - 05:53 PM
#2
Posted 13 February 2011 - 02:45 AM
World Map: 60 Minutes ETOPS
The "60-minute rule" was waived in 1964 for 3-engined aircraft. This opened the way for the development of wide-body intercontinental trijets such as the Lockheed Tristar and DC-10. By then, only 2-engined jets were restricted by the "60-minute rule".
Outside the USA, other countries followed ICAO regulations, which allowed for 90 minutes' diversion time. This fact was exploited by Airbus, launching the world's first twin-engined high-bypass turbofan engine wide-body airliner, the Airbus A300, in 1974. It was about three-quarters the size of DC-10s and Tristars and, for an equivalent load traveling the same distance, was cheaper to operate.
As a result, twin-engined aircraft like the A300, Boeing 737 and 767 became alternatives to three- and four-engined aircraft.
World Map: 90 Minutes ETOPS
The FAA was the first to approve ETOPS guidelines in 1985. It spelled out conditions that need to be fulfilled for a grant of 120 minutes' diversion period, which is sufficient for direct transatlantic flights.
TWA was awarded the first ETOPS rating in May 1985 for the Boeing 767 service between St. Louis and Frankfurt, allowing TWA to fly its aircraft up to 90 minutes away from the nearest airfield: this was later extended to 120 minutes after a federal evaluation of the airline's operating procedures. Today, ETOPS forms the bulk of transatlantic flights.
World Map: 120 Minutes ETOPS
In 1988, the FAA amended the ETOPS regulation to allow the extension to a 180-minute diversion period subject to stringent technical and operational qualifications. This made 95% of the Earth's surface available to ETOPS flights. The first such flight was conducted in 1989. This set of regulations was subsequently adopted by the Joint Aviation Authorities (JAA), ICAO and other regulatory bodies.
World Map: 180 Minutes ETOPS
So to summarize: 1964-1985 ETOPS 90 Minutes, 1985 - 1988 ETOPS 120 Minutes, 1988- ETOPS 180 Minutes.
Source
Not saying I know what to do with this info, but the research is here for reference.
#3
Posted 13 February 2011 - 04:58 PM
#4
Posted 13 February 2011 - 06:03 PM
I mean, the great circle calculation for distance is complex enough without calculating position and heading. There is no simple way to check if a portion of the route leaves the etops area. You would be stuck with piecemeal checks that have to examine ever potential position along the route against a list of ETOPS coverage airport. For example, just south of Greenland on the ETOPS-90 map, there is a narrow gap of only about 50-100 mi that is not ETOPS, but if you were to check the position of the aircraft every hour of flight, you would only have about a 15-25% chance of the check picking bouncing the route for failing to meet ETOPS. Alternatively, you could go through every possible route combination and give it's great circle ETOPS rating, and the addition distance to go into smaller ETOPS ratings. With something like 2-3,000 airports (more maybe?) in the game, there would be 6 million+ combinations.
Point it, this would make the routing many times more complex than it currently is. While it would be a neat feature, the programming and data-mining time would be better spent on other efforts.
#5
Posted 14 February 2011 - 12:41 AM
I would ask how someone would suggest this is implemented...
I mean, the great circle calculation for distance is complex enough without calculating position and heading. There is no simple way to check if a portion of the route leaves the etops area. You would be stuck with piecemeal checks that have to examine ever potential position along the route against a list of ETOPS coverage airport. For example, just south of Greenland on the ETOPS-90 map, there is a narrow gap of only about 50-100 mi that is not ETOPS, but if you were to check the position of the aircraft every hour of flight, you would only have about a 15-25% chance of the check picking bouncing the route for failing to meet ETOPS. Alternatively, you could go through every possible route combination and give it's great circle ETOPS rating, and the addition distance to go into smaller ETOPS ratings. With something like 2-3,000 airports (more maybe?) in the game, there would be 6 million+ combinations.
Point it, this would make the routing many times more complex than it currently is. While it would be a neat feature, the programming and data-mining time would be better spent on other efforts.
woah, woah, woah, slow down...woah.
I thought perhaps the GC mapper (used as a reference by many websites) http://www.gcmap.com/ could be used to return a result of etops = yes/no....
#6
Posted 14 February 2011 - 01:04 AM
woah, woah, woah, slow down...woah.
I thought perhaps the GC mapper (used as a reference by many websites) http://www.gcmap.com/ could be used to return a result of etops = yes/no....
No
R6 - NSW Airlines
#7
Posted 14 February 2011 - 01:23 AM
GC Mapper only has distance calculations, I think. The nearest thing to that I can come up with was this: http://www.gcmap.com...0&EV=450&EU=kts That represents SFO-NRT with 90 min ETOPS circles at 450kts. It's easy enough for us to see that this is not ETOPS-90 compliant, but I don't see where it returns a TRUE/FALSE for ETOPS compliance. The only reason it's easy to see by human eye is because of the image. But analyzing the image is probably more work than doing a groud-up ETOPS compliance calculator (no small task)
On the above route, it passes though ETOPS circles for PDX, Ketchekan (KTN), ANC, Unalaska (DUT), Kamchatka (PKC), Sapporo (CTS) and finally, NRT. Also, there are about 4 more circles that do not have airports in AE. Say we, for example, break the route down into 100 mi segments. We start at 500 miles from departure (assuming 500 mi gets out just outside the 90 min ETOPS for SFO), and for 500-600, we find the nearest airport to the begining of that segment that the aircraft could land on. We then test the end of that segment (mi 600) and if that falls within the same airport's ETOPS circle, we are certain that the 100mi segment is ETOPS compliant. So we do this over 40 segments (5,000 mi - 2x 500 mile dep & arr circle = 4,000 mi / 100mi = 40 total) With those, we get one PDX-KTN circle segment, 1 KTN-ANC, 1 ANC-DUT, 1 DUT-PKC, and 1 PKC-CTS. Using the great circle calculation for distance and heading, we can find a true heading to the ETOPS airport in question from the begining of the 'cross-circle' segment. Using vector addition to combine the cross-circle segment with the distance to airport, we then use our 90 min circle constant (500 mi) to find what point in the segment crosses the circle (say for this example it's at 55 mi into the 20th segment--3,055 mi into route). We then do the same process for the end of segment with the next ETOPS airport. If it turns out that we're in the circle 45 mi from the end of the segment, the route is ETOPS compliant, if not, it isn't.
That sounds simple enough, but keep in mind that currently, you have a distance, demand, and supply that factor into the relatively simple route calculations on AE. Also keep in mind that calculating the great circle heading requires about as much processing as calculating the distance (so about doubling the processing load over a whole-route in the current system). Then consider that that must be duplicated 40 times for even a basic setup like above. That gives us 80x the processing we currently have for a single route, and I haven't even addressed building the chain of ETOPS-circle airports.
That said, after thinking about this a bit more and posting the above, I think this may actually be viable...if the ETOPS compliance were only calculated on North & South America to any other continent and Aussi to Africa, the processing load could be dramatically cut down. There are enough route finding programs out there that could be duplicated to chain together ETOPS airports. By finding the furthest point from the route to the nearest route circle intersection (what you might refer to as the crotch between two circles), we could use that point as a VIA in the routing for distance calculation. Every route which ETOPS compliance is calculated could just store the result as a database entry so it would only have to be calculated once...and if there is a via point, we could have an ETOPS compliant range and a 3/4 engine range (which would be shorter). Basically one good run through a game would give us the vast majority of ETOPS calculations permenently in the database and have them for future use.
I hope all that makes sense. I see it all in my mind very clearly, but I'm not sure I got all of it out
#8
Posted 14 February 2011 - 02:50 AM
mischkaffee,
GC Mapper only has distance calculations, I think. The nearest thing to that I can come up with was this: http://www.gcmap.com...0&EV=450&EU=kts That represents SFO-NRT with 90 min ETOPS circles at 450kts. It's easy enough for us to see that this is not ETOPS-90 compliant, but I don't see where it returns a TRUE/FALSE for ETOPS compliance. The only reason it's easy to see by human eye is because of the image. But analyzing the image is probably more work than doing a groud-up ETOPS compliance calculator (no small task)
On the above route, it passes though ETOPS circles for PDX, Ketchekan (KTN), ANC, Unalaska (DUT), Kamchatka (PKC), Sapporo (CTS) and finally, NRT. Also, there are about 4 more circles that do not have airports in AE. Say we, for example, break the route down into 100 mi segments. We start at 500 miles from departure (assuming 500 mi gets out just outside the 90 min ETOPS for SFO), and for 500-600, we find the nearest airport to the begining of that segment that the aircraft could land on. We then test the end of that segment (mi 600) and if that falls within the same airport's ETOPS circle, we are certain that the 100mi segment is ETOPS compliant. So we do this over 40 segments (5,000 mi - 2x 500 mile dep & arr circle = 4,000 mi / 100mi = 40 total) With those, we get one PDX-KTN circle segment, 1 KTN-ANC, 1 ANC-DUT, 1 DUT-PKC, and 1 PKC-CTS. Using the great circle calculation for distance and heading, we can find a true heading to the ETOPS airport in question from the begining of the 'cross-circle' segment. Using vector addition to combine the cross-circle segment with the distance to airport, we then use our 90 min circle constant (500 mi) to find what point in the segment crosses the circle (say for this example it's at 55 mi into the 20th segment--3,055 mi into route). We then do the same process for the end of segment with the next ETOPS airport. If it turns out that we're in the circle 45 mi from the end of the segment, the route is ETOPS compliant, if not, it isn't.
That sounds simple enough, but keep in mind that currently, you have a distance, demand, and supply that factor into the relatively simple route calculations on AE. Also keep in mind that calculating the great circle heading requires about as much processing as calculating the distance (so about doubling the processing load over a whole-route in the current system). Then consider that that must be duplicated 40 times for even a basic setup like above. That gives us 80x the processing we currently have for a single route, and I haven't even addressed building the chain of ETOPS-circle airports.
That said, after thinking about this a bit more and posting the above, I think this may actually be viable...if the ETOPS compliance were only calculated on North & South America to any other continent and Aussi to Africa, the processing load could be dramatically cut down. There are enough route finding programs out there that could be duplicated to chain together ETOPS airports. By finding the furthest point from the route to the nearest route circle intersection (what you might refer to as the crotch between two circles), we could use that point as a VIA in the routing for distance calculation. Every route which ETOPS compliance is calculated could just store the result as a database entry so it would only have to be calculated once...and if there is a via point, we could have an ETOPS compliant range and a 3/4 engine range (which would be shorter). Basically one good run through a game would give us the vast majority of ETOPS calculations permenently in the database and have them for future use.
I hope all that makes sense. I see it all in my mind very clearly, but I'm not sure I got all of it out
Hey rotaryspd,
Thanks for your detailed response. I appreciate the detail of your proposal; I simply thought the GC mapper had a means by which to verify etops compliance. It seems like the site owner Karl is quite active posting news etc to the main page (anyone else here with GC mapper in their bookmarks!?) maybe we should be in touch with him to find out how his mapper does the calculations and borrow the math for our non profit use? As we all know there are many routes in AE being operated in clear violation of ETOPS..I play as if ETOPS were real, but I know it would add another (profit) challenge to AE. If someone does get in touch with him mention his air canada link is out of date.
#9
Posted 24 February 2011 - 01:19 AM
#10
Posted 26 February 2011 - 01:38 AM
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