MIA/MVA vs IAF crossing altitudes

[FoggyWindow]

Working ARTCC and we own to the ground with a ton of non towered airports. MIA is 4000 but the IAF crossing alt is 4100. Are you legal to descend them to 4000 if you clear them for the straight in? They aren't doing the procedure turn so they have no need to abide by the PT/IAF crossing alt of 4100.

 

[squawkIFR]

you can clear them for the approach below the depicted iaf altitude as long as its not lower than the mva

 

[NavyTrev]

It can’t be below the MVA or the minimum altitude intercept that’s posted on the chart with a lightning bolt. I’ve always seen them at the final approach fix.

 

[squawkIFR]

It can’t be below the MVA or the minimum altitude intercept that’s posted on the chart with a lightning bolt. I’ve always seen them at the final approach fix.

because the lightning bolt indicates the final approach fix on a precision approach

maltese cross is the faf for non precision approach

 

[7four11]

5-9-4

 

[32andBelow]

It can’t be below the MVA or the minimum altitude intercept that’s posted on the chart with a lightning bolt. I’ve always seen them at the final approach fix.

We don’t have MVA at center. You should tell him to cross at or above 4100 unless he’s on an airway that contains the IAF then you can just clear him for approach.

 

[DankVectorz]

We don’t have MVA at center. You should tell him to cross at or above 4100 unless he’s on an airway that contains the IAF then you can just clear him for approach.

4000 is fine since the MIA is 4000

 

[32andBelow]

4000 is fine since the MIA is 4000

I taught to always give the higher due to how the approach is flight checked and possible reception issues.

 

[FoggyWindow]

The .65 just says you can't assign an altitude below the MIA/MVA, doesn't say it can't be below the IAF crossing altitude if your MIA is lower. My interpretation is that if they are doing the procedure turn, then they need to abide by the altitude for the procedure turn since its set off the TERPS of the approach, but if I'm clearing them for the straight in then they aren't doing the procedure turn, then I'm going to the bottom of my MIA.

 

[Stinger]

I remember last year when you asked this over on stuckmic. I thought it was all hashed out there extremely well...especially by BeaconSlash.
I don't really like linking to other threads, but in this case I will for those that didn't see it: Starting IFR Approach Below the Crossing Altitude for IAF

Is your example using the VOR/DME-A at T82?
There's a 3,049' antenna south of that final. Over the years the MIA/MVA people have rounded up and down at different times compared to the Approach Procedure people...That's how the discrepancy shows up with crossing altitudes being 100' higher on the IAP than your MIA. I would guess that both your MIA and the crossing at STV used to be 4,000' but procedures drifted apart and some point.

 

[FoggyWindow]

I remember last year when you asked this over on stuckmic. I thought it was all hashed out there extremely well...especially by BeaconSlash.
I don't really like linking to other threads, but in this case I will for those that didn't see it: Starting IFR Approach Below the Crossing Altitude for IAF

I'm writing an article for the NATCA SW communications team and this is our Q of the month. I just need some fresh input and to get some varied opinions and StuckMic is dead.

 

[NavyTrev]

because the lightning bolt indicates the final approach fix on a precision approach

maltese cross is the faf for non precision approach

The lightning bolt is indicating the minimum glideslope intercept altitude, which yes indicates the final approach segment of the approach.

I believe the lightning bolt indicates the final approach point, the Maltese cross indicates final approach fix.
But then it says something about ATC can issue a lower published intercept altitude. But I’ve never come across one. Need to bust out the AIM.

 

[Stinger]

vectoring an aircraft in an MVA of 5000 to intercept a GS, which unless flight checked has maximum usable altitude of 4500 and 10 miles).

If you're able to provide radar monitoring, the GS/LOC service volumes don't mean much. "Maintain 5000 until established on the localizer, cleared ILS approach" when the aircraft will intercept 30 miles from the runway is legal.

 

[bwdmad1]

as well as maximum usable altitudes (imagine vectoring an aircraft in an MVA of 5000 to intercept a GS, which unless flight checked has maximum usable altitude of 4500 and 10 miles).

It's not altitude of 4500 its feet above the transmitter.

 

[Glide47]

It's not altitude of 4500 its feet above the transmitter.

Correct....the example I was thinking of is in Alaska....on the coast, at sea level