Moderators: richierich, ua900, PanAm_DC10, hOMSaR
Kai Tak IGS 13 in 2021
Of course this is purely hypothetical since Kai Tak no longer exists as an operating airport. If it still existed today, would/could the IGS 13 approach have been replaced or overlaid by an RNAV approach with the same course? Would there have been any operational limitations (i.e. terrain, building proximity, etc.) that would have prevented an RNAV approach into RWY 13?
Re: Kai Tak IGS 13 in 2021
I think a modern LNAV / VNAV system could be tailored quite well for that approach, curved legs incorporating vertical guidance already exist at several airports
Re: Kai Tak IGS 13 in 2021
With an RNP AR curved approach one would even be able to use lower minima than back in the days.
Re: Kai Tak IGS 13 in 2021
My guess is that it wouldn't be replaced, at least until they could do something like a GGS (a GLS to the checkerboard, like they did with the IGS), because WAAS/SBAS/LPV is not really a thing for most commercial airliners and LNAV/VNAV minima tend to be fairly high. I could totally see them doing some sort of RNP AR approach though - those are made for places like Kai Tak.
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- CanukinUSA
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Re: Kai Tak IGS 13 in 2021
GLS approaches are not required to be straight in to the runway like an ILS. The GLS could be straight in towards the checkerboard like before then turn towards the runway threshold with the autopilot engaged to auto land on the runway. The manual maneuvering that the pilot had to do before would not be required. The only issue would be that the GLS is currently limited to Cat I. GLS will likely be approved for Cat II and Cat III in the next few years.
Re: Kai Tak IGS 13 in 2021
Agent wrote:With an RNP AR curved approach one would even be able to use lower minima than back in the days.
Whilst I’m a big fan of RNP-AR, I’m not sure obstacle clearance requirements would work. It would be an interesting exercise for a PANS-OPS procedure design mock task.
Re: Kai Tak IGS 13 in 2021
CanukinUSA wrote:GLS approaches are not required to be straight in to the runway like an ILS. The GLS could be straight in towards the checkerboard like before then turn towards the runway threshold with the autopilot engaged to auto land on the runway. The manual maneuvering that the pilot had to do before would not be required. The only issue would be that the GLS is currently limited to Cat I. GLS will likely be approved for Cat II and Cat III in the next few years.
There are curved approach designs that end up in an ILS, usually involving a DME arc.
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- CanukinUSA
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Re: Kai Tak IGS 13 in 2021
Those curved approach’s are not on short final approach when you are just a few hundred feet above the ground like the IGS 13 was at the old VHHH. GLS can handle curves on short final like that. I don’t know if I still have an approach chart for that approach but from what I recall you flew the IGS (which was basically an ILS located at the checkerboard) and then once you were visual at about 400 to 600 feet ASL had to turn at an angle of bank of about 25 to 30 degrees angle of bank about 60 degrees of heading change while descending to the runway threshold. If you turned to shallow you would end up in the terminal building and if you turned to much the harbor.
Re: Kai Tak IGS 13 in 2021
RNAV (GPS) approach to 13L in JFK would be a close example.
https://resources.globalair.com/dtpp/gl ... 0RZ13L.PDF
https://resources.globalair.com/dtpp/gl ... 0RZ13L.PDF
Re: Kai Tak IGS 13 in 2021
CCA wrote:RNAV (GPS) approach to 13L in JFK would be a close example.
https://resources.globalair.com/dtpp/gl ... 0RZ13L.PDF
Also similar would be the circle to land RNAV 01R at SFO:
https://i.imgur.com/mj0RD0m.png
I wonder if threading the needle between the buildings in Kowloon City would create issues with the GPS signal and resulting accuracy necessary for the RNAV approach? I guess we will never know the answer to that question.
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- CanukinUSA
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Re: Kai Tak IGS 13 in 2021
Please see the KSFO RNP to GLS Report that was done after Flight Testing by Boeing, United and Delta in SFO in 2016:
https://laas.tc.faa.gov/documents/Docs/ ... Dec_16.pdf
https://laas.tc.faa.gov/documents/Docs/ ... Dec_16.pdf