Rnav altitudes

[Rnavsrdumb]

Just have a question about rnav crossing altitudes and mvas.

Let's say I have an rnav fix called usles and the crossing altitude is 7000... The mva is 065. The next fix after usles is dumbs at 059. Can I clear an aircraft at or above 065 at usles?

For clarification this is an rnav z approach clearance in an approach control.

I'm being told that "proceed direct usles, cross usles at or above 065, cleared rnav z rwy15 approach." Is illegal because the aircraft could descend to 059 after usles and this would put the aircraft too low for what is intended on the rnav.

 

[32andBelow]

Yah. Cross useless at or above 065 then descend via. Or descend via except cross usles at or above 065 depends if he’s already on the arrival or direct usles to join

But why?? Chances are the pilot isn’t going to reset their FMS to be 500 feet lower if you need it for traffic then I’d assume you’d issue cross @

 

[DankVectorz]

If it’s an approach you don’t need to say the “descend via”

 

[32andBelow]

If it’s an approach you don’t need to say the “descend via”

It sounded like he was talking about an arrival. Idk.

 

[eltors0]

Just have a question about rnav crossing altitudes and mvas.

Let's say I have an rnav fix called usles and the crossing altitude is 7000... The mva is 065. The next fix after usles is dumbs at 059. Can I clear an aircraft at or above 065 at usles?

Sure.

 

[AnyTrafficPleaseAdvise]

Just have a question about rnav crossing altitudes and mvas.

Let's say I have an rnav fix called usles and the crossing altitude is 7000... The mva is 065. The next fix after usles is dumbs at 059. Can I clear an aircraft at or above 065 at usles?

I don’t know the .65 answer, but If there is a difference between an MIA and an IAF crossing altitude I use the higher of the two. I never clear an aircraft below the MIA, but I have seen people descend aircraft to an MIA which is lower than the crossing altitude on an approach plate.

 

[DankVectorz]

I don’t know the .65 answer, but If there is a difference between an MIA and an IAF crossing altitude I use the higher of the two. I never clear an aircraft below the MIA, but I have seen people descend aircraft to an MIA which is lower than the crossing altitude on an approach plate.

MVA not the same as MIA

 

[AnyTrafficPleaseAdvise]

MVA not the same as MIA

Center puke here. We don’t have those

 

[DankVectorz]

Center puke here. We don’t have those

Question specially said MVA so I’m guessing this isn’t a center question

 

[Termine]

I'm being told that "proceed direct usles, cross usles at or above 065, cleared rnav z rwy15 approach." Is illegal because the aircraft could descend to 059 after usles and this would put the aircraft too low for what is intended on the rnav.

What it comes down to is the altitude published on the segment between USLES and DUMBS, not the published crossing altitude at USLES, because of the Note at the end of 4–8–1b2: An aircraft is not established on an approach until at or above an altitude published on that segment of the approach. Regardless of the published crossing altitude, on a non-precision approach the aircraft is allowed to drop to that published segment altitude as soon as they pass USLES, and the procedure designers have to protect for that. If the published segment altitude is 065 or lower (and it would have to be, if the crossing altitude at DUMBS is 059) then you are legal to assign them "Cross USLES at 065, cleared approach."

The one very fine distinction is that if you issue "cross at 070" then they are established as soon as they reach USLES. But if you issue "cross at 065" then they are not established until they are just past USLES. Shouldn't make a difference in the real world, right?

Two other points to keep in mind:

1. For a conventional approach the higher crossing altitude may be to ensure signal reception, so you should be wary of assigning a lower one.
2. When vectoring to final, you aren't allowed to assign a lower FAF crossing altitude than is published (5–9–1c/d).