Lost comms in TAA

[fiveoboy01]

Why 5800? You are outside the 30nm ring. Why is everyone ignoring that part?

I'd go up to 6500.

Granted, the OROCA guarantees 1000 feet clearance.. or 2000 feet(is this a designated mountainous area? I don't know)... but if I'm the pilot, I don't know where the obstacles or terrain are and if I'm in IMC and not being vectored, that scares me. Granted, if you're 35 miles out, you might not be able to get to 6500 before crossing that 30nm boundary, but I'd think it would be prudent to get as high as you can before getting there.

 

[EdFred]

I am 99.9% sure it is a mountainous area. Though if I could get my 3000fpm climb like I did Saturday, I could probably make it to 6500 in like 30 seconds. That's just some quick math off the top of my head.

 

[aterpster]

I'd go up to 6500.

Granted, the OROCA guarantees 1000 feet clearance.. or 2000 feet(is this a designated mountainous area? I don't know)... but if I'm the pilot, I don't know where the obstacles or terrain are and if I'm in IMC and not being vectored, that scares me. Granted, if you're 35 miles out, you might not be able to get to 6500 before crossing that 30nm boundary, but I'd think it would be prudent to get as high as you can before getting there.

The boundary of a TAA has a 4 mile buffer.

 

[fiveoboy01]

I just did the math and at Vy, I'd need a 380 ft/second climb rate to get to 6500 in the 5 mile distance. That would be well within the capability of the airplane depending on weather and weight.

 

[EdFred]

The boundary of a TAA has a 4 mile buffer.

But you may be outside that buffer by more than that depending where that 35nm is from the FIELD - as stated in the OP.

 

[fiveoboy01]

The boundary of a TAA has a 4 mile buffer.

That I did not know.

In any case, I might climb anyways. No harm can come from it. Not like I'd need to slam dunk to get down to the lower altitudes.

 

[fiveoboy01]

But you may be outside that buffer by more than that depending where that 35nm is from the FIELD - as stated in the OP.

The plate shows 12 miles from AUBIN to the runway threshold so in this instance, well within the buffer zone. If I'm interpreting it correctly.

 

[EdFred]

The plate shows 12 miles from AUBIN to the runway threshold so in this instance, well within the buffer zone. If I'm interpreting it correctly.

I drew out some circles on a chart. You can be over 12 miles outside the 30nm MSA from SUMNA when 35nm "NW" of the field. (for me that's anywhere between 290 and 340.

 

[Henning]

Why 5800? You are outside the 30nm ring. Why is everyone ignoring that part?

That's minimum, gotta look around myself, ahhh, SVT is sweet, no big rocks. But I'll still go up for 5800' at the IAF. Without terrain guidance in the cockpit I would revert to airway style procedure and use the minimum altitude I can safely identify myself clear for.

 

[fiveoboy01]

I drew out some circles on a chart. You can be over 12 miles outside the 30nm MSA from SUMNA when 35nm "NW" of the field. (for me that's anywhere between 290 and 340.

You're right. I was measuring distance from AUBIN. Move that measuring point to the field and things change depending where you're at.

 

[roncachamp]

The MVA (minimum vectoring altitude)is a minimum altitude used by controllers who are, well, vectoring you. Or at least have you in the proper sector on radar. Pretty basic IFR stuff done daily just about everywhere there is radar service (maybe less so in completely flat areas with no obstructions)

Once I lose communications, I'm no longer being vectored. While it is probably completely safe to stay at 5,000 to complete the approach, my choice is to head back up to what is now my minimum IFR altitude for that segment of the approach (5800 to SUMNA).

The MVA is based on terrain, obstacles, and controlled airspace. Flight at the MVA is not limited to aircraft being vectored and does not guarantee that aircraft can be vectored as it may be below radar coverage and too low for direct pilot/controller communications.

 

[Skyhawk890]

Thanks to everyone that chimed in with their opinion. As the OP, and my first post I might add, I never expected such a response!!

Perhaps a bit more clarity is in order here. For my scenario, let's assume an IFR departure from 0B1-Bethel, ME with an initial clearance from TRACON cleared direct to KLEW (as filed) maintain 5000. Although 0B1 is in mountainous terrain, departing 0B1 to the southeast towards KLEW is moving away from terrain and 5000 is commonly issued/approved because it is such a short flight and is above the MVA in that direction.

Assume that while en route, the pilots asks for the RNAV RWY 4 approach into KLEW and the controller says to expect that...moments later the radio dies and you are in IMC. For argument sake, perhaps in real world, the controller wouldn't say simply to "expect that", he might say to 'expect that' with a vector heading toward SUMNA / when able cleared direct SUMNA or something like that...I don't think it changes the discussion much as my real question is about the altitude. I know from previous experience that ATC will keep me at 5000 until I get closer to the IAF and/or until I get established on the approach and are cleared for it---to descend to the published altitude. I am quite sure that 5000 will keep me clear of obstacles for my route of flight, thus the routine 5000 clearance often given.

My concern is more general - for locations that I do not know. ATC cleared me for 5000 with 'expect the RNAV RWY 4 approach' before radios go out. Whether they descended me from 10000 or I was at 5000 all along, the fact is that I'm entering (or inside) a TAA when the radios go out. I agree with those that said that in this scenario, I am no longer receiving vectors and therefore no longer afforded the convenience of flying at MVA or thereabout. My inclination would be to immediately climb to 5800 to SUMNA if between 30-12nm from SUMNA as stated in the TAA. If I'm greater than 30 nm from SUMNA, since I'm no longer being vectored at 5000 and not on a published route, then I should climb to at least 6500 OROCA (or 7000 for IFR-Eastbound) until 30 NM from SUMNA, then drop back down to 5800 until 12 out and then down to 3100 and so on.

Someone mentioned about never getting in legal trouble and I tend to agree under the circumstances - I was more concerned about what is "safe" and expected by ATC and the regs.

Am I thinking correctly here?

 

[fiveoboy01]

My concern is more general - for locations that I do not know. ATC cleared me for 5000 with 'expect the RNAV RWY 4 approach' before radios go out. Whether they descended me from 10000 or I was at 5000 all along, the fact is that I'm entering (or inside) a TAA when the radios go out. I agree with those that said that in this scenario, I am no longer receiving vectors and therefore no longer afforded the convenience of flying at MVA or thereabout. My inclination would be to immediately climb to 5800 to SUMNA if between 30-12nm from SUMNA as stated in the TAA. If I'm greater than 30 nm from SUMNA, since I'm no longer being vectored at 5000 and not on a published route, then I should climb to at least 6500 OROCA (or 7000 for IFR-Eastbound) until 30 NM from SUMNA, then drop back down to 5800 until 12 out and then down to 3100 and so on.

Someone mentioned about never getting in legal trouble and I tend to agree under the circumstances - I was more concerned about what is "safe" and expected by ATC and the regs.

Am I thinking correctly here?

It's exactly what I would do in that scenario. Whether or not it would be necessary is debatable but if I lose coms in IMC, I'm not taking chances especially in an unfamiliar area.

 

[dtuuri]

Am I thinking correctly here?

I don't think so. Your questions are posed from the point of view of being surprised by a radio failure and being uncertain about what you are expected to do. Shouldn't you plan your flight from the beginning with radio failure in mind at each point of your route? Then you'd know what to do, exactly, and need not pull altitudes from a hat, such as OROCA, that may or may not be the minimum IFR altitude for the segment you are flying.

dtuuri

 

[Caramon13]

Maybe this is so obvious as to be laughable, but why not pull out your VFR sectional and see if there are any obstacles along the "direct" route? Instead of guessing at the 6500 OROCA (which by the way seems to be based on the upper left quadrant of that area) and the low enroute which has absolutely NO terrain details?

Doing so you'd see that 5000 is a bit excessive but more than adequate to maintain distance from terrain on that jump from 0B1 to KLEW.

Granted you are IFR not VFR, but you can at least get an understanding of your situation and not go descending/ascending based on guessing.

 

[fiveoboy01]

Then you'd know what to do, exactly, and need not pull altitudes from a hat, such as OROCA, that may or may not be the minimum IFR altitude for the segment you are flying.

I guess I don't see how that's pulling an altitude from a hat. If he's not on a published route, what altitude should he be selecting in his scenario?

 

[Jaybird180]

I guess I don't see how that's pulling an altitude from a hat. If he's not on a published route, what altitude should he be selecting in his scenario?

Hmmm...destination airport is right under V3. A peruse of a VFR chart indicates that he's safe (does not imply legal) at 5000 in the >D route given.

 

[Caramon13]

Right I understand the rules of IFR vs VFR are different, but in a lost comms situation, if you truly are concerned about terrain, use what you have in the cockpit to get a better overall understanding of the situation. Simply looking at an enroute map and climbing to 5800 uninformed based on a TAA arc when you were told 5000 doesn't make sense to me.

What (other than the arc) told you to climb 800 feet?

Are you on an airway with an MEA: No.
Were you told to expect an altitude: No.
What were you assigned: 5000

Fly 5000.

Don't trust that? Fine, find out what is around you, break out the VFR chart, open your EFB, something, but have a reason why you decided to fly something other than what was either an airway, expected or assigned altitude.

I found this nugget here:

• Unless otherwise cleared by ATC, you are expected to fly the charted altitudes when you are inside a segment of the TAA and cleared both to an IAF and for the approach. You were told to expect the approach, you were not cleared for the approach, though you were cleared to the IAF SUMNA.
• If you are cleared to an IAF, but not yet cleared for the approach, you are not automatically cleared to descend to a TAA altitude. Fly your last assigned altitude. <----This is what you should do, note this mentions descending, but not climbing, still you should fly 5000, disagree? See above comments.
• If you have any question about the altitude you should fly, ask ATC. <- Obviously you can't do this one since your comms are out.

What about the approach into KEYW as another example? The MSA/TAA is 15K for that RNAV 9 approach. You lose comms after being cleared to CHETS at 5K. Are you going to climb 10K more just because the arc told you so?

 

[fiveoboy01]

Right I understand the rules of IFR vs VFR are different, but in a lost comms situation, if you truly are concerned about terrain, use what you have in the cockpit to get a better overall understanding of the situation. Simply looking at an enroute map and climbing to 5800 uninformed based on a TAA arc when you were told 5000 doesn't make sense to me.

It might not make sense, but it would ensure you don't hit anything.

Are you on an airway with an MEA: No.
Were you told to expect an altitude: No.
What were you assigned: 5000

Fly 5000.

If I was cleared direct to the IAF at 5000 prior to my coms going out, I'd stay at 5000. If I'm not direct and now have to navigate my own way to the IAF without vectors, I'm climbing.

If you are cleared to an IAF, but not yet cleared for the approach, you are not automatically cleared to descend to a TAA altitude. Fly your last assigned altitude.

Does that instruction take into account lost coms?

The FARs state in the case of lost coms, that you fly the last altitude assigned, the minimum altitude for IFR, or the EFC altitude, whichever is highest.

If I'm in the soup and I lose a radio, I'm not shuffling out my vfr chart or bothering trying to figure out where I should be in relation to obstacles when the altitudes are clearly listed on the IFR chart and approach plate.

What about the approach into KEYW as another example? The MSA/TAA is 15K for that RNAV 9 approach. You lose comms after being cleared to CHETS at 5K. Are you going to climb 10K more just because the arc told you so?

That's kind of an extreme example, but the answer is no, because the plate clearly shows a balloon and cable to 14,000 feet in the restricted area northeast of the airport which is the obvious reason for the high MSA. If it's obvious like in that case, then sure, don't climb... but if I'm not completely sure, I'm going up.

 

[Caramon13]

It might not make sense, but it would ensure you don't hit anything.

Agreed, up is usually free of issues (barring an airway or something), but what indications (if anything) do you have that ATC gave you an altitude that would put you at harm? Especially since you were cleared to an IAF at that altitude?

Does that instruction take into account lost coms?

The FARs state in the case of lost coms, that you fly the last altitude assigned, the minimum altitude for IFR, or the EFC altitude, whichever is highest.

If I'm in the soup and I lose a radio, I'm not shuffling out my vfr chart or bothering trying to figure out where I should be when the altitudes are clearly listed on the IFR chart and approach plate.

Oh believe me I totally understand, been there done that I'm not shuffling through paperwork either if I need to aviate. I did bold the item in your quote that is most applicable here, I was assigned an altitude. Why would ATC assign me an altitude TO an IAF if that would put me into terrain? What if there is traffic above me that they have descending and I climb into that traffic because they expected me straight and level? I'm not talking to them and since it's all IMC that shouldn't be an issue, but who knows? They assigned me 5000 for a reason.

That's kind of an extreme example, but the answer is no, because the plate clearly shows a balloon and cable to 14,000 feet in the restricted area northeast of the airport which is the obvious reason for the high MSA. If it's obvious like in that case, then sure, don't climb... but if I'm not completely sure, I'm going up.

Yes, I agree and it's not the SAME exact example being an MSA instead of a TAA, but you get the idea. Yeah in this case you can see the restricted area, but if that wasn't on the chart would you still climb 10,000 feet? I dunno, I think if I was that paranoid about ATC trying to kill me I'd risk breaking out a map to see what's up. Otherwise there'd be no reason for me to expect a change at all.

 

[fiveoboy01]

I think we might be agreeing on one point... If cleared direct to the IAF at a certain altitude, I'd probably stay there but make a point to look for obstructions.. my point about shuffling paper is valid but lets face it, a lot of us have autopilot and an EFB, so this really doesn't put us in danger of losing control of the airplane while scoping the area on a chart for obstacles. ATC probably didn't try to fly you into the side of a hill, trust but verify.

 

[PPC1052]

I think we might be agreeing on one point... If cleared direct to the IAF at a certain altitude, I'd probably stay there but make a point to look for obstructions.. my point about shuffling paper is valid but lets face it, a lot of us have autopilot and an EFB, so this really doesn't put us in danger of losing control of the airplane while scoping the area on a chart for obstacles. ATC probably didn't try to fly you into the side of a hill, trust but verify.

The problem I have with this is the assumption that because you were assigned 5000, it would be safe the rest of the way for a direct course. Given that you were being vectored, how are we to know that another vector (or two) isn't necessary to circumnavigate a 5000 foot plus obstruction? If I'm being vectored within a TAA at an altitude lower than shown on the chart, and lose communications, I would climb to the TAA sector altitude just to be safe.

 

[fiveoboy01]

Correct, that's why my scenario was where the controller cleared you direct the IAF at 5000 before coms were lost. Maybe I did a bad job of spelling that out but that's what I meant.

 

[Henning]

Maybe this is so obvious as to be laughable, but why not pull out your VFR sectional and see if there are any obstacles along the "direct" route? Instead of guessing at the 6500 OROCA (which by the way seems to be based on the upper left quadrant of that area) and the low enroute which has absolutely NO terrain details?

Doing so you'd see that 5000 is a bit excessive but more than adequate to maintain distance from terrain on that jump from 0B1 to KLEW.

Granted you are IFR not VFR, but you can at least get an understanding of your situation and not go descending/ascending based on guessing.

This is where a glass moving map comes in real handy, SVT exponentially more so.

 

[Caramon13]

This is where a glass moving map comes in real handy, SVT exponentially more so.

Definitely Henning. I fly with a iPad with SVT (Garmin GDL 3D 39). It's not a G1000, but it definitely warns you of upcoming terrain and/or obstacles in flight.

I haven't tried it on an approach in IMC yet, but then again, I haven't really needed it where I fly.

 

[flyingron]

The MVA is lower than the OROCA, which is why he was cleared down. However, it seems only you and I are the ones that notice that he's not inside the MSA yet based on the position he stated in the OP.

OROCA isn't obligatory anyhow, it's just a crutch for those to figure out what the actual minimum IFR altitude on the particular route.

 

[fiveoboy01]

And if you're not on a published route?

Is it still a crutch?

 

[EdFred]

OROCA isn't obligatory anyhow, it's just a crutch for those to figure out what the actual minimum IFR altitude on the particular route.

So when I'm not on a T or Q or V or whatever published route (similar to the OP), which altitude am I to use exactly?

 

[Caramon13]

So, Ed, I take it you are using the OROCA as the minimum altitude anywhere off-airway?

That's...interesting.

So if you flew down to KEYW like I mentioned earlier, you'd file for 15K, off-airway then?

 

[EdFred]

Well, the MSA says 15000 as well.

Personally, I'd file direct to DVALL V157 or DEEDS V601 or DROWN V3

 

[Caramon13]

Well, the MSA says 15000 as well.

Personally, I'd file direct to DVALL V157 or DEEDS V601 or DROWN V3

Absolutely, I did the same thing myself DVALL V157 EYW last time I went down there.

But let's say you said, nah, or were coming from dade-collier and went direct from VEGIE to KEYW, off airway. You would still go ahead and fly up to 15K if you lost comms? Assuming you were given direct CHETS at 5K for example (before you lost comms).

Not trying to side-track the discussion, and I realize this is an EXTREME example. I'm new to IFR flying personally and I find this kinda stuff fascinating

 

[EdFred]

Since your balloon is the exception, and is inside an R-space which will be visible on my GPS, probably not. But if that 15000 is west of Denver, I'm not gonna hope those vectors sent me through a pass.

Though I would expect them to give me STRAP or STING first. That puts me on a published route.

 

[aterpster]

That's kind of an extreme example, but the answer is no, because the plate clearly shows a balloon and cable to 14,000 feet in the restricted area northeast of the airport which is the obvious reason for the high MSA. If it's obvious like in that case, then sure, don't climb... but if I'm not completely sure, I'm going up.

Take a look at the MSA on F70 RNAV 18, French Valley, CA.

 

[fiveoboy01]

Take a look at the MSA on F70 RNAV 18, French Valley, CA.

Looks like the high MSA is due to terrain to the northeast, right on the edge of the 25 mile boundary. Not exactly the same as an island surrounded by water, but your point is valid

 

[flyingron]

So when I'm not on a T or Q or V or whatever published route (similar to the OP), which altitude am I to use exactly?

And if you're not on a published route?

Is it still a crutch?

How about following the regulation (91.177)

If no applicable minimum altitude is prescribed inparts 95 and 97 of this chapter, then—
(i) In the case of operations over an area designated as a mountainous area inpart 95 of this chapter, an altitude of 2,000 feet above the highest obstacle within a horizontal distance of 4 nautical miles from the course to be flown; or
(ii) In any other case, an altitude of 1,000 feet above the highest obstacle within a horizontal distance of 4 nautical miles from the course to be flown.
​

The OROCA for the quandrant you are travelling through isn't even necessarily a legal altitude. You must look 4 miles either side of your route of flight. If you're in a quadrant that has some significant terrain more than four miles from where your route takes you, the OROCA may be excessively higher than the minimum legal IFR altitude.

Yeah, it's a crutch to come up with a legal number (if your'e doing it right). As I stated, it's not necessarily the minimum legal altitude in general, and certainly the MVA could be lower.

 

[EdFred]

What's awesome is how the low enroutes have terrain on them to make planning that much easier.

 

[flyingron]

What's awesome is how the low enroutes have terrain on them to make planning that much easier.

Nobody said the enroute is the only chart necessary.

 

[fiveoboy01]

But what about DME?

 

[flyingron]

What about the approach into KEYW as another example? The MSA/TAA is 15K for that RNAV 9 approach. You lose comms after being cleared to CHETS at 5K. Are you going to climb 10K more just because the arc told you so?

Despite their cartological similarity TAA and MSA's have NOTHING to do with each other. The thing on the KEYW plates is a MSA. It has NO navigation significance.

 

[denverpilot]

Since your balloon is the exception, and is inside an R-space which will be visible on my GPS, probably not. But if that 15000 is west of Denver, I'm not gonna hope those vectors sent me through a pass.

Technically there aren't any "fifteeners" in the Colorado Rockies, so 15 would clear all terrain. Not by a large margin in a few places, but it would clear all.

14 on the other hand... 60 things you could hit, some of which are more ridges than peaks.

https://en.m.wikipedia.org/wiki/List_of_Colorado_fourteeners