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Guest damnlimey

Visual vs. Precision glideslope

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I'm just curious if there's a difference in technique between flying a precision (CAT III) ILS glideslope vs a Visual one. My local airport, San Jose, California (KSJC) has currently got the precision runway (30L) closed for extension, forcing all flight to use the visual 30R instead. If you look at the attached jpeg, you'll see that the touchdown points for the two runways are very closely aligned, but it seems to me, driving on the freeway that passes the eastern end of the airport, that planes coming in are quite noticably lower on approach to 30R than they used to be on 30R.Is this normal - does ILS allow a higher approach until over the threshold?

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Hi Keith,SJC RWY 30R is about 900' longer than 30L and 30L has a displaced threshold. I'd guess that aircraft landing on 30L look like they are higher because they are, since the touchdown zone is further to the northwest than on 30R.You can download an airport diagram at:http://naco.faa.gov/d-tpp/0408/00693AD.PDFTo my knowledge, the SJC ILS RWY 30L is only a CAT I approach and there are no CAT II or CAT III approaches at SJC. There are sidestep minimums defined for the ILS RWY 30L, so it's likely that, in IMC, aircraft may fly the ILS to RWY 30L, then sidstep to 30R.Part 121 and 135 operations aim to touch down 1000' beyond the threshold regardless of whether they are on a visual approach, a precision approach, or a non-precision approach.Hope that helps.John

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JohnThanks for the information. I have noticed the occasional side-step procedure in use, I guess that even though the runway (30L) is currently closed for construction, the ILS is still operational.

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