Starting IFR Approach Below the Crossing Altitude for IAF

[FoggyWindow]

For an uncontrolled airport in center airspace, crossing alt for an approach is 4500, MIA in the area is 4000. If an acft is at 4000, can you clear him on the approach if he’s 500ft below the crossing alt for the approach? If so, what phraseology do you use?

 

[j_time41]

What kind of an approach

 

[NovemberEcho]

“5 mile from fix, cross fix at 4000/maintain 4000 until established on the localizer/segment of Approach, cleared ILS/gps/vor/etc approach.

clearing them is just like any other clearance. Being below the crossing altitude doesn’t affect anything except they’re not considered established on the approach until their altitude matches up with what it should be for wherever they are on the approach

 

[j_time41]

Yup. Now you can just clear them without all the bs if they are inside the published TAA as well

 

[FoggyWindow]

No TAA, but what’s the phraseology for clearing them if they’re above the crossing altitude for the IAF?

 

[FoggyWindow]

Typically, I either say “cross fix at or above 045, cleared gps rwy17 approach”, but if they are at 040 and the crossing is at 045, there’s no phraseology I can find that says how to clear them. The “maintain 040 until established on a segment of the approach” isn’t in the book as far as I can tell.

 

[FoggyWindow]

As are having a debate at work is how this came about.

 

[NovemberEcho]

Typically, I either say “cross fix at or above 045, cleared gps rwy17 approach”, but if they are at 040 and the crossing is at 045, there’s no phraseology I can find that says how to clear them. The “maintain 040 until established on a segment of the approach” isn’t in the book as far as I can tell.

so tell them cross fix at 4000. So long as it’s above the MVA doesn’t matter if they’re below the crossing altitude. All the crossing altitude is is where the approach and 3 degree descent or whatever it is will take them to the runway. If they cross fix below that they just start the descent later or shallower.

and if they’re above the crossing altitude cross fix at or above 4500

 

[Stinger]

I don't think you'll ever get a consensus on this one. I see both arguments. If you're providing radar monitoring, it shouldn't cause any issues to cross the fix on a GPS approach below the published altitude as long as it meets your MVA. For a ground based radio signal, the higher altitude may be for reception issues, which could cause an issue for the pilot in receiving the course guidance.
If you do issue a lower crossing altitude than published, don't be surprised if the pilot either questions it or just climbs without telling you.

 

[NovemberEcho]

I don't think you'll ever get a consensus on this one. I see both arguments. If you're providing radar monitoring, it shouldn't cause any issues to cross the fix on a GPS approach below the published altitude as long as it meets your MVA. For a ground based radio signal, the higher altitude may be for reception issues, which could cause an issue for the pilot in receiving the course guidance.
If you do issue a lower crossing altitude than published, don't be surprised if the pilot either questions it or just climbs without telling you.

I’ve been issuing clearance below the crossing altitude for almost 10 years now. Never once has it been questioned let alone a pilot climbs on their own. If they did climb they’d be getting a phone number with the brasher.

 

[j_time41]

“Blah blah blah maintain 4000 until established on a published portion of the approach, cleared blah blah”
I don’t see both sides of the argument. All the altitude means on the approach is for it to meet the flight check parameters that they wanted for it in ideal conditions.
There are a few places I do this too, we have had the same debate, but if he is above the minimum until established, it can’t be illegal.

 

[FoggyWindow]

I agree, however, the argument stems from the lack of phraseology in the book. Nothing says you can or can’t. For example, we have an approach that starts at 4100 in an area where the MIA is 4000. I always just say to cross the IAF at or above 4100 cuz I only ever descend them to 5000 until I’m ready to clear them. I’ve only ever had somebody at 4000 prior to the approach once and that’s when this debate was sparked.

 

[BeaconSlash]

The rules are there, it just gets compiled from various locations in the .65. This isn't any sort of guessing game, and in all sincerity shouldn't even be a debate. If anything, this is about as clean as it gets, it's just not consolidated in a single location very well.


4-5-6 Minimum En Route Altitudes covers staying at/above the MEA/MOCA for published routes, or MIA/MVA for unpublished (i.e. direct or point-to-point-not-airway).

4-8-1.b.2 - Assigned an altitude to maintain until theaircraft is established on a segment of a published
route or instrument approach procedure.

4-8-1.b.2 Note 3 - An aircraft is not established on an approach until at or
above an altitude published on that segment of the
approach.

All the little altitude logic switches are here.

Per your example:

MIA 4,000, IAP MEA 4,500. This simply isn't enough information to fully answer your question.

Some questions:

Is the MEA stated for the initial or intermediate approach segment?
If the the MEA is for the initial approach segment, what is the intermediate approach segment MEA?
Are they joining at an IAF or IF? If so, which one?
Is there a Hold In Lieu or Procedure Turn involved?

This is a LOT easier to answer if you give a direct example.

 

[slater]

Are they on a segment of the aproach already? If so, distance from fix, cleared aproach.

 

[FoggyWindow]

I can’t upload a pic from my iphone, but the GPS rwy 32 to T82 airport is a good example. The MIA in the area is 040, but the crossing over the IAF is 045. Occasionally an acft will request 040 to get below clouds and then start the approach.

 

[BeaconSlash]

Ok, thank you for the direct example. This is a a pretty simple case compared to many others (IAP chart below).

If the aircraft is cleared for a straight in approach (i.e., bypassing the Hold-in-Lieu) from CIRIX, clearing someone to join the approach at 4,000 is legal.

You fully meet the three requirements quoted above.

More practically speaking though, the instant they hit CIRIX inbound, their IAP MEA is 3,300 to REYOS, lower than the 4,000 they are at when they join the IAP. Clean.

If they aren't in a position to do the straight in approach, then they need to be at or above 4,500.

The published holding pattern doesn't exist below 4,500, that is the minimum holding altitude by definition. If you clear someone for approach when below 4,500 from a position where they need to execute that course reversal, they aren't on a published segment of the approach once they cross CIRIX outbound per the clarification of Note 3, which in turn creates a violation of 4.8.1.b.2. Basically, they're in no man's land.

Even if you argue "well, he stays at 4,000 feet until he hits CIRIX, and that's above my MIA, so it's ok," well...

TERPS had a reason to designate that hold minimum altitude at 4,500 instead of at your MIA of 4,000. According to the Holding Fix Record for CIRIX, there is an Adverse Assumption Obstacle controlling the minimum altitude (in fact, the minimum altitude was raised from 4,000 to 4,500 in May 2012).

I get this is down in the weeds and are things neither the controller nor the pilot are expected to know, think, or worry about, just the number on the plate... simply stated, I think it's harder if not impossible to establish good standing to clear someone to fly the holding pattern as published below the minimum holding pattern altitude.

In short...

If the aircraft can meet the 90 degree rule at CIRIX, they can be cleared straight in at 4,000. If not, they need to be at 4,500 and allowed to execute the Hold-In-Lieu.

PS - Addressing the TAA, I'd say this doesn't restrict you in terms of the 4,000 for a straight in as discussed, it just serves to reduce your phraseology a little by reducing phraseology you need to state when clearing someone for approach direct CIRIX, and they're AOA 4,500 and within 30 NM.

If anyone has counter-arguments, I'm willing to listen, not trying to say I have the final word, but I think I've got a tight case.

 

[Stinger]

I get this is down in the weeds and are things neither the controller nor the pilot are expected to know, think, or worry about, just the number on the plate

BeaconSlash nailed it. I've gone down into the weeds on this in the past, not as far as the Holding Fix Records, but enough to know that there's conditions that need to be met for it to be completely legal. Enough for me to say that I just follow the approach plate altitudes when the pilot is on their own navigation unless some unusual or special situation comes up. Vectors to final (majority of my approaches) will be at the MVA or FAF altitude, whichever is higher.

 

[j_time41]

So I wasn’t thinking they needed to do the turn to final, I just assumed he wouldn’t give it if there was a published altitude for the turn in, which is clearly 4500.

So Beacon, you are saying in a nutshell 4000 is legal anytime and every time in this case (following turn in and vector rules for RNAV) except if they need to do the turn to final crossing back over CIRIX, correct?

Good explanation, Thankyou.

 

[BeaconSlash]

So I wasn’t thinking they needed to do the turn to final, I just assumed he wouldn’t give it if there was a published altitude for the turn in, which is clearly 4500.

So Beacon, you are saying in a nutshell 4000 is legal anytime and every time in this case (following turn in and vector rules for RNAV) except if they need to do the turn to final crossing back over CIRIX, correct?

Good explanation, Thankyou.

Only a Sith deals in absolutes, amirite? But if someone is getting vectored to final, you're basically right, 4000 would be legal.

My discussion was centered around Chapter 4 IAP clearances. If you move in to Ch 5 Radar Arrivals (i.e., vectors to final, presuming the capability exists), procedure turns and therefore Holds-In-Lieu are prohibited when receiving vectors to final per FAR 91.175(j). Ergo, once again, the holding pattern is bypassed. At that point it's the same logic applies as discussed above.

That said, unless there's a significant advantage or urgency in tightening the final just a few miles (only 7 between REYOS FAF and CIRIX to begin with)... it's probably easier to clear direct CIRIX from a position that abides by the 90 degree rule and clear them for a straight in approach from CIRIX. But that's strictly opinion.

Can you clarify your meaning of "do the turn to final crossing back over CIRIX?" Are you referring to executing the Hold-In-Lieu?

 

[FoggyWindow]

Thanks for that interpretation. None of us got deep enough into the .65 I guess LOL