Originally Posted by
OPNLguy
Length aside, SJC's parallel runways are also relatively close together, such that higher traffic volumes would also be impacted by the same type of ceiling issues as SFO (it's not the fog at SFO, but cloud ceilings) that preclude the use of visual approaches that provide the higher airport acceptance rate (AAR). Not to mention that many of the same folks that doth protest runway construction to further separate the runways at SFO would protest the theoretical expansion of flights at SJC.
Yes but the clouds burn off much sooner at SJC, and don't return until much later. There's plenty of days when I can look up to the north from my office near SJC and see low clouds still hanging over the Bay, while SJC and the Santa Clara Valley are clear. So my point is that IF you are going to put a local airport over its IMC limit, it should be SJC, not SFO.
That said, they really need to develop a technology that has an error bound of something less than 2400 feet. Seems like it should be possible to focus a beam such that at 25 nm out, you can get < 700' of error, using much higher frequencies. ILS uses 108.10 MHz to 111.95 MHz. Why such extremely low frequencies? Those very low frequencies spread out from their source and can't be focused with any precision. Why don't they use narrowly focused millimeter-wave? When supplemented with GPS, shouldn't that be accurate enough to guide planes to runways with 700' of separation in zero visibility?