Just curious...the * near the 540....and the arbie fix minimums....

when would you use the arbie fix minimums (S-LOC 24R) as opposed to the normal S-LOC mins of 540.?

No bashing me please...serious question

 

You have to be careful about doing this at LAX. Some of the ILS glideslopes will take you below minimum segment altitudes.

 

My suggestion with approaches like these, is fly the glideslope, but do it in Vertical Speed mode (not approach mode). Use the altitude preselect to ensure that you are not deviating from the minimum altitudes. When you cross each step down, change the preselect and keep the descent going. Once you get to the final step down altitude (at which you will intercept the G/S), arm the approach mode to capture the glide...

This also works well for procedures like the Korry arrival into LGA.

 

Rat,

If you're in a sitation where ur using the straight in localizer minimums (GS out, or you broke your airplane) then you'd have the option of using the arbie minimums if you're A/C had the capability to identify the arbie fix, which is used with 3.6DME from the LOC. It's not terribly uncommon, just something to help you get a little lower when you're using minimums that'll probalby keep you in the soup.

 

You mean you dont fly like that all the time???

 

The altitude restrictions depicted in the profile view are valid IF, AND ONLY IF, you are established on the approach (I read that as LOC alive) once that is true, check the DME, if inside of MERCE (<16.2) then start down to cross FAF @2200, or GS intercept, make sense? Otherwise, in the turn, you may not have obstacle clearance or be above min vectoring altitude(not your problem, since you can't tell what it is). Thats most likely why it says maintain 4000 till MERCE on the segment from PERMS to MERCE. There must also be a reason why there is no PT allowed on this approach, perhaps not enough protected airspace with associated obstacle clearance in the LOC path.

Might not be wrong to start down but, not a good idea, IMO. I must first confess, I fly cargo, so I don't really give a hoot about how the boxes feel in the descent, but if planned for, the whole thing should be able to be done smoothly and comfortably for most any aircraft. I have not been to LAX lately, but isn't the speed limit there just 200 KIAS?

I'd maintain 4000 till MERCE or LOC intercept (alive) then descend to the next restriction. I think if you were to do that, you could not be wrong, you just might be intercepting the GS from above, and you should have 10-12 DME to fix it, but maybe only 4-6 DME to meet your carrier's stabilized approach requirements so, your milage may vary.

ImperialxRat

A good question, if you need the extra 80', and you just might on those crappy days with GS inop. As for the when would you use the arbie fix minimums (S-LOC 24R) as opposed to the normal S-LOC mins of 540.?

I think, one uses the ARBIE mins of 460 vice 540 when you are flying the S-LOC 24R and have DME, being careful of the runway lighting status for the RVR restrictions prior to commencing. In other words, you must cross ARBIE at 540, if you can identify ARBIE (has to be with DME at 3.4, and DME is not required equipment for the approach in general, there is the matter of that timing thing ), then and only then, you can continue down to 460 on the LOC. Have I missed anything here?

JMHO, standing by to be corrected.

 

Thanks for all your input guys. When I flew this approach in the sim, coming from the north, I would hit the LOC and be slightly above glide. I'm thinking that joining the gldeslope and then later X-checking it at JETSA is probably the best idea for passengert comfort. And I can't see why it would be illegal.
This is what I fugured: I'm flying at around 140kts in that part of the approach, so zero-wind VS to keep the GS is 700fpm. When I joined the LOC from the north transition I'm already about half-scale high on the GS and rapidly going full scale. If all I wanted was to intercept the GS from there, I'd need a minimum of about 1,000fpm. If instead I wanted to descend faster than the GS, so to hit 2,200 and intercept the GS from below, I would need at least 1,500+ fpm (more like 2000fpm). I'm not sure it would be a good idea to be descending so fast at such low altitude, only to then level-off and wait for the GS to come down. Sounds like a lot more work, power changes and possibility for an unstabilized approach.
Any comments?

Velocipede, thanks for the heads-up. I'll keep that in mind. In my example MERCE is the last step-down-fix before GS intercept, so as long as you are passed MERCE there's nothing to worry about. But if you came from PALAC it might be a different story.

 

Sounds like you've got the idea. Good luck in your sim check.

 

Thanks guys for the answers =)

 

Don't fly IFR in canada then. Intercepting the GS from above with little distance in IMC is common. Its called a short gate approach. Keep peter pan and the easter bunny company in your fantasy world because you won't like the real one.