Below the GS at SFO again

[Capn Bloggs]

CDFA on a non precision approach, add 50 feet to MDA and treat as a DA. You won't bust minima and if you are visual you should be stable to continue.

As pointed out before, best by RetiredF4, using this method you cannot get to the MDA and still land if the cloudbase is just above the MDA. In fact, it puts more pressure on crews because they have to make a snap decision with fewer protections than afforded by a precision approach where you are allowed to go below the DA and won't hit anything. NPAs by definition may well have poorer tracking positioning and offset alignment with the runway.

It is better to get to the MDA a little early, below the "glideslope", have a good look, and then GA if necessary. Now if you don't know how to organise/do that, then a database 3° CDFA NPA is the next best option.

[Lonewolf_50]

Captain Bloggs, your summary sounds a lot like what people are taught on their way to an instrument rating. The key to success in that method is staying ahead of the aircraft (mentally) as a crew, and a good "who is looking out, who is on gauges" CRM standard. And of course, if at MAP all is not well, GA and try again, or try another approach, or head to alternate ...

[golfyankeesierra]

It is better to get to the MDA a little early, below the "glideslope", have a good look, and then GA if necessary

Sure, for the little planes that might work, but we are talking about 777's here...
Personally I abandoned your approach when I left the pistons behind.

[West Coast]

Capt Bloggs

Increases in safety often comes with a price. If the once in a blue moon consequence is I don't get in because the wx is at the difference between dive and drive and a constant angle altitudes, so be it.

I like the constant angle NPA procedures, my workload is lessened and the bigger picture is easier to maintain.

[bugg smasher]

Regarding the original subject of this thread, after having spoken to a few guys who were around that day, and I stress, the official investigation is still pending, but this being a rumor board; the EVA aircraft crossed the San Mateo Bridge slightly above 600', a full 1300' below the recommended altitude. It is not clear if they were descending, or level. ATC alerted the aircraft twice, with no response, and then issued the Go Around instruction, to which they responded.

I would say, and this is my personal opinion only, they were frighteningly low.

[sb_sfo]

bugg

I live abeam the bridge, and if you're right, they were only about 400' above it, google lists 135' to the water. Frightening to the traffic on the bridge, too, cause that approach is usually about 1615 lcl, early rush hour!

[Capn Bloggs]

Originally Posted by West Coast

Increases in safety often comes with a price. If the once in a blue moon consequence is I don't get in because the wx is at the difference between dive and drive and a constant angle altitudes, so be it.

I like the constant angle NPA procedures, my workload is lessened and the bigger picture is easier to maintain.

Fair enough.

[bugg smasher]

The traffic pattern at San Carlos is 800', so at least they were underneath that..., although it might be disconcerting for a student pilot in a 152 to see a triple seven slide by below him...

[BOAC]

What happens to San C traffic when SFO 28 traffic flies the RNAV or ILS?

[bubbers44]

RNAV 28L for KSFO restricts arrivals to no lower than 1800 ft until well past San Carlos so with their 800 ft pattern at least 1,000 ft separation exists.

[BOAC]

So why 1900 for a visual?

[olasek]

It is logical that in VMC they want to increase vertical separation between SFO arrivals and San Carlos pattern traffic but in IMC everybody is under positive radar control plus no one at San Carlos is flying traffic pattern hence no longer need for extra buffer in separation.

[BOAC]

Originally Posted by olasek

but in IMC everybody is under positive radar control plus no one at San Carlos is flying traffic pattern hence no longer need for extra buffer in separation.

- why do you assume it is 'IMC' before aircraft fly the RNAV or ILS - not so. I thought also we had seen a restriction now on 'no visuals' for 'foreign' pilots regardless of weather?

[underfire]

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[bugg smasher]

BOAC, today we were offered the choice of LOC/DME Y or RNAV (GPS) Z to 28R. The FAF in both cases is AXMUL, which has a crossing restriction of 1800', and also happens to be conveniently, and not so surprisingly, co-located with the San Mateo Bridge.

A brief examination of both these charted procedures should answer any remaining questions you may have. Happy to assist with any further queries, as and where I am able.

[Auberon]

Originally Posted by BOAC

So why 1900 for a visual?

It's a valid question. The RNAV (GPS) RWY 28L has an 1800 minimum altitude between HEMAN and DUYET. DUYET is actually slightly before the bridge, so aircraft on the RNAV are crossing the bridge below 1800.

[bubbers44]

BOAC, you can see that there is at least 1,000 ft separation so why did you bring up the question?

[bubbers44]

How do I know, now you have 1100 ft clearance so it is safer. That is what the RNAV approach says versus the visual. Ask Bay approach.

[bubbers44]

BOAC, 1,000 ft separation is normal. All ILS and RNAV approaches to 28L have 1,000 ft or greater separation. The 800 ft traffic pattern will have 1,000 ft separation.

[Auberon]

Originally Posted by bubbers44

How do I know, now you have 1100 ft clearance so it is safer. That is what the RNAV approach says versus the visual. Ask Bay approach.

Is it really safer? 1900' at the bridge puts you above the PAPI. 1800' is closer to being on the PAPI. There seem to have been a lot more issues with unstable visual approaches to KSFO than conflicts with KSQL traffic.