Originally Posted by OK
The bridge is the logical landmark to prescribe a recommended altitude on a visual to clear the 1500' top, in this case by at least 400'. It is a convenient guideline.
- thank you for a detailed post. I agree with what you say, but I still feel the restriction on the 'visual' is unnecessary. I asked a similar question of SFO ATC on the ATC forum but received no answer. I cannot see why 400' clearance is required on a visual but not on an RNAV. The 'assessed' collision risk must be the same, surely?
The RNAV plots 1800 at 5.5 from touchdown, (the bridge is around 5, so logically about 1650 at the bridge) but the visual for some reason asks for 1900 at the bridge. Why?
I actually think the charts are bizarre. A 2.85 slope (RNAV) crosses DUYET (given as 5.7 from threshold) while the ILS (3 degrees) crosses DUYET INT at 1800' at 5.5 miles from touchdown, so one assumes DUYET and DUYET INT are not the same point. Just to make it real fun, the visual suggests I-SFO (loc/DME) for vertical guidance (at 3 degrees, which 1900 isn't) and then charts SFO DME.....
Was there some sort of 'recreational' event going on when these were drawn up? San Franciso, and all that.........................