Transponder setting in IMC while in Class G

dmccormack said:
How about Tower Enroute Control?

(Anyone used that recently? I haven't yet...)

The only problem is -- that's only available in more densely populated areas....
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AFaIK, primarily a east coast and west coast deal. Not very common where the large areas of Class A capped Class G exist.
 
JeffDG said:
In fact, if you plan the terrain right, you could probably sneak under the 1,200 AGL on the airways while maintaining your 1,000 above obstacles altitude and make a lot of flights without ever touching controlled airspace.
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Obstacles can be constructed up to 200' in height without notifying the FAA and appearing on the charts. Even if they weren't a factor, where could you do what you suggest and maintain a cardinal altitude correct for direction of flight?
 
gismo said:
This whole discussion seems to beg the question of "Why don't the regs allow ATC to issue clearances in Class G (or it's equivalent)?"

Seems to me that there's no reason for "uncontrolled" airspace to exist at all, at least to the extent that IFR traffic isn't provided with some means of safe separation beyond the big sky concept. Other countries have Class F which in some (but not all) cases allows for exactly that while leaving the less restrictive VFR ops of Class G.

One might argue that ATC control cannot be exercised unless there is radio communication but for a remote area beyond radio range the one-in, one-out method would still work and I'd bet that most areas where Class G reaches 14,500 MSL, communication would be possible at the upper altitudes of the Class G.
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In the US, where the tools needed for ATC to provide separation services exist, the airspace tends to be controlled and separation is provided.
 
roncachamp said:
Obstacles can be constructed up to 200' in height without notifying the FAA and appearing on the charts. Even if they weren't a factor, where could you do what you suggest and maintain a cardinal altitude correct for direction of flight?
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I mistakenly said "probably" when I meant "possibly".

Lots of times we're talking about people who are intimately familiar with the route and all the obstacles (charted and otherwise).

Alternatively, depending on ceilings, these are areas where you're not required to maintain 1000' or even 500' AGL VFR. If you can get to a 1000' ceiling, you can descend to that IFR (cardinal altitudes are for cruise, you can descend through other altitudes provided you're 1000' above obstacles within 4nm), break out, fly under the airway VFR (clear of clouds-Class G) at 900', then climb back into the clouds and be on your way...I'm saying could, not should!
 
JeffDG said:
I mistakenly said "probably" when I meant "possibly".

Lots of times we're talking about people who are intimately familiar with the route and all the obstacles (charted and otherwise).

Alternatively, depending on ceilings, these are areas where you're not required to maintain 1000' or even 500' AGL VFR. If you can get to a 1000' ceiling, you can descend to that IFR (cardinal altitudes are for cruise, you can descend through other altitudes provided you're 1000' above obstacles within 4nm), break out, fly under the airway VFR (clear of clouds-Class G) at 900', then climb back into the clouds and be on your way...I'm saying could, not should!
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Where? At what location are you doing this?
 
It's been a long time since I've read 91.179 and I had forgotten that there is a whole section giving cardinal altitude rules for uncontrolled airspace. Hopefully the defense attorney will ask why that section is in the regs if the FAA ever claims that IFR in uncontrolled airpace is illegal.
 
Palmpilot said:
It's been a long time since I've read 91.179 and I had forgotten that there is a whole section giving cardinal altitude rules for uncontrolled airspace. Hopefully the defense attorney will ask why that section is in the regs if the FAA ever claims that IFR in uncontrolled airpace is illegal.
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Cardinal directions apply above 3000' AGL....
 
roncachamp said:
Obstacles can be constructed up to 200' in height without notifying the FAA and appearing on the charts. Even if they weren't a factor, where could you do what you suggest and maintain a cardinal altitude correct for direction of flight?
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Stick to the controlling. There's no requirement for altitude <3000ft agl.
 
dmccormack said:
Cardinal directions apply above 3000' AGL....
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SkyHog said:
Stick to the controlling. There's no requirement for altitude <3000ft agl.
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Remember that this conversation has been about IFR flight in uncontrolled airspace. The 3000' limit only applies to VFR flight. So Steven's right.

§ 91.179 IFR cruising altitude or flight level.

[...]

(b) In uncontrolled airspace. Except while in a holding pattern of 2 minutes or less or while turning, each person operating an aircraft under IFR in level cruising flight in uncontrolled airspace shall maintain an appropriate altitude as follows:
(1) When operating below 18,000 feet MSL and—
(i) On a magnetic course of zero degrees through 179 degrees, any odd thousand foot MSL altitude (such as 3,000, 5,000, or 7,000); or
(ii) On a magnetic course of 180 degrees through 359 degrees, any even thousand foot MSL altitude (such as 2,000, 4,000, or 6,000).
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Of course, I'd certainly be interested in what constitutes "uncontrolled airspace" above 18,000' MSL, which is what sections (b)(2) through (b)(4) talk about.
 
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gprellwitz said:
Remember that this conversation has been about IFR flight in uncontrolled airspace. The 3000' limit only applies to VFR flight. So Steven's right.
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Well... that's the rub -- is this a "VFR" flight? Since the hypothetical pilot is flying IFR in uncontrolled airspace, is he/she bound by IFR controlled airspace rules?

It's really a rather moot point, as Class G vis requirements are pretty poor.
 
dmccormack said:
Well... that's the rub -- is this a "VFR" flight? Since the hypothetical pilot is flying IFR in uncontrolled airspace, is he/she bound by IFR controlled airspace rules?

It's really a rather moot point, as Class G vis requirements are pretty poor.
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Not when those rules specify controlled airspace. If they don't specify or if they specify uncontrolled airspace, as the section I quoted did, then yes, s/he is bound by them.
 
dmccormack said:
Well... that's the rub -- is this a "VFR" flight? Since the hypothetical pilot is flying IFR in uncontrolled airspace, is he/she bound by IFR controlled airspace rules?

It's really a rather moot point, as Class G vis requirements are pretty poor.
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But those aren't IFR controlled airspace rules, they're specifically for IFR in uncontrolled airspace
 
dmccormack said:
Well... that's the rub -- is this a "VFR" flight?
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No.

Since the hypothetical pilot is flying IFR in uncontrolled airspace, is he/she bound by IFR controlled airspace rules?
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No, he's bound by IFR uncontrolled airspace rules. In controlled airspace you cruise at the altitude assigned by ATC, in uncontrolled airspace you cruise at a cardinal altitude proper for the direction of flight without regard to your altitude above the ground.

It's really a rather moot point, as Class G vis requirements are pretty poor.
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Class G viz requirements do not apply to IFR flight.
 
gprellwitz said:
Of course, I'd certainly be interested in what constitutes "uncontrolled airspace" above 18,000' MSL, which is what sections (b)(2) through (b)(4) talk about.
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Perhaps the Alaska Peninsula west of longitude 160°00'00" West.
 
gprellwitz said:
Of course, I'd certainly be interested in what constitutes "uncontrolled airspace" above 18,000' MSL, which is what sections (b)(2) through (b)(4) talk about.
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roncachamp said:
Perhaps the Alaska Peninsula west of longitude 160°00'00" West.
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Or, I suppose Hawaii, Santa Barbara Island, or Farallon Island, or the Keys south of Rock Harbor. It's not depicted on the sectional, of course, since Class A isn't depicted.
§ 71.33 Class A airspace areas.

(a) That airspace of the United States, including that airspace overlying the waters within 12 nautical miles of the coast of the 48 contiguous States, from 18,000 feet MSL to and including FL600 excluding the states of Alaska and Hawaii, Santa Barbara Island, Farallon Island, and the airspace south of latitude 25°04'00" North.
(b) That airspace of the State of Alaska, including that airspace overlying the waters within 12 nautical miles of the coast, from 18,000 feet MSL to and including FL600 but not including the airspace less than 1,500 feet above the surface of the earth and the Alaska Peninsula west of longitude 160°00'00" West.
(c) The airspace areas listed as offshore airspace areas in subpart A of FAA Order 7400.9S (incorporated by reference, see §71.1) that are designated in international airspace within areas of domestic radio navigational signal or ATC radar coverage, and within which domestic ATC procedures are applied.
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dmccormack said:
Since the hypothetical pilot is flying IFR in uncontrolled airspace, is he/she bound by IFR controlled airspace rules?
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According to the Part 91 table of contents, instrument flight rules (= IFR) are 91.167 through 91.199. Some of them are worded "in controlled airspace...," some of them are worded "in uncontrolled airpace...," and some of them don't state any limitation on where they apply. So I would say that the ones that say "in controlled airspace..." don't apply in class G, and the rest do.
 
roncachamp said:
In the US, where the tools needed for ATC to provide separation services exist, the airspace tends to be controlled and separation is provided.
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Given that there are places where an airplane could legally travel between two airports at the appropriate cruising altitude while remaining entirely inside Class G, I don't see why ATC couldn't separate such traffic by limiting the number of aircraft in the same area to one, much as they do with the IFR traffic arriving or departing when no radar coverage is available.

What tools are missing for the hypothetical flight described in an earlier post on this thread? What's needed beyond a means of communicating with the pilot's before and after the flight?
 
JeffDG said:
"Proceed as filed" is a clearance, and ATC cannot issue a clearance for uncontrolled airspace.

For a "pure G" flight, ATC cannot clear you. They have no jurisdiction over the airspace.
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They could advise you... For example, the Tower only has jurisdiction over the runways. When the blimp went to take off, they called the tower and tower advised that there was no immediate inbound or outbound traffic and that they could "take off at your discretion." The word "cleared" was never used.
 
gismo said:
Given that there are places where an airplane could legally travel between two airports at the appropriate cruising altitude while remaining entirely inside Class G, I don't see why ATC couldn't separate such traffic by limiting the number of aircraft in the same area to one, much as they do with the IFR traffic arriving or departing when no radar coverage is available.

What tools are missing for the hypothetical flight described in an earlier post on this thread? What's needed beyond a means of communicating with the pilot's before and after the flight?
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Permit just one aircraft at a time to operate IFR in a huge airspace area? That will ensure separation, but it's horribly inefficient.

Why bother with "the appropriate cruising altitude" if only one aircraft at a time is allowed to operate IFR?
 
roncachamp said:
Permit just one aircraft at a time to operate IFR in a huge airspace area? That will ensure separation, but it's horribly inefficient.

Why bother with "the appropriate cruising altitude" if only one aircraft at a time is allowed to operate IFR?
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You think the hemispherical rule for IFR is any more effective than the Big Sky theory at preventing midair collisions?

As to the area to be sterilized, it wouldn't necessarily be all that large, just enough to maintain separation plus some margin for inaccuracies in the flight plans. This doesn't seem a lot different than separation in the pre-radar days except that now you have computers instead of "boats" on a chart table.
 
gismo said:
You think the hemispherical rule for IFR is any more effective than the Big Sky theory at preventing midair collisions?
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It should prevent roughly half the mid-airs. I think that qualifies as "any." :smile:
 
Palmpilot said:
It should prevent roughly half the mid-airs. I think that qualifies as "any." :smile:
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Why would it do that? Limiting IFR altitudes to thousands gives you a maximum of 16 at less than 18K' (can't use 1K or 18K). If you don't have defined altitudes, there are an "infinite" number, cut down by the average height of an aircraft. Admittedly, the former is subject to the vagaries of altitude resolution, but pitot-static systems are subject to regular checks. So, if you're relying on big-sky theory, having no altitude restrictions would decrease the chance of a collision!
 
gismo said:
You think the hemispherical rule for IFR is any more effective than the Big Sky theory at preventing midair collisions?
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Yes.

As to the area to be sterilized, it wouldn't necessarily be all that large, just enough to maintain separation plus some margin for inaccuracies in the flight plans. This doesn't seem a lot different than separation in the pre-radar days except that now you have computers instead of "boats" on a chart table.
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How do you limit the size of the sterile area when you have no inflight communications?
 
gprellwitz said:
Why would it do that? Limiting IFR altitudes to thousands gives you a maximum of 16 at less than 18K' (can't use 1K or 18K). If you don't have defined altitudes, there are an "infinite" number, cut down by the average height of an aircraft. Admittedly, the former is subject to the vagaries of altitude resolution, but pitot-static systems are subject to regular checks. So, if you're relying on big-sky theory, having no altitude restrictions would decrease the chance of a collision!
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Having no altitude restrictions would allow aircraft to choose the same optimum altitude without regard to direction of flight. The hemispheric rule reduces the chances of head-on encounters.
 
roncachamp said:
Having no altitude restrictions would allow aircraft to choose the same optimum altitude without regard to direction of flight. The hemispheric rule reduces the chances of head-on encounters.
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The Big Sky may explain why we have so few mid-airs below 3,000', not in the vicinty of an airport.

While the happen, and we've all had close calls, when you consider how rare a mid-air is, it seems to support the contention that free choice of altitude is just as statistically "safe" as assigned altitudes.

(I've had more than one old timer tell me not to cross VORs at precise altitudes for this same reason: "Always cross at +/- 100 or so when flying VFR..." I've listened and considered, but haven't practiced that much -- especially now as a CFI doing BFRs etc I see how rare is the pilot who can stick his/her altitude and VOR passage)
 
roncachamp said:
Yes.



How do you limit the size of the sterile area when you have no inflight communications?
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You limit it by the length of the flight (such flights can't cross airways and thus are held to relatively short lengths), and/or by the filed routes coupled with clearance times and ETEs. For example, two flights between the same two airports (in the same direction) could be allowed to be in air simultaneously if a slower aircraft departed with a significant delay after the first one's void time. Intersecting flights paths could be separated by altitude restrictions.

In the pre-radar days (and when the radar fails) multiple flights are allowed on the same airways with separation provided by a combination of position reports and time based estimates of future positions. Granted, today such flights are expected to be able to communicate with ATC over the entire route, but there's no guarantee that the comms won't fail and IME the distance between reporting points often exceeds the total length of any flight that never enters controlled airspace.

I agree the current operating procedures probably aren't quite sufficient for this but I don't see why appropriate procedures couldn't be implemented and I'm certain that something could be developed that would provide more safety than the current system of luck and a big sky.
 
roncachamp said:
Having no altitude restrictions would allow aircraft to choose the same optimum altitude without regard to direction of flight. The hemispheric rule reduces the chances of head-on encounters.
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I think Richard Bach hit the nail on the head when he described the Hemispherical Altitude rule by saying that compliance only guarantees that all mid-air collisions in cruise flight will occur at angles of less than 180 degrees. Granted, there's a little more to it than that since a flight tracking due east could theoretically only run into an airplane within a 90 degree sector and you'd have to be tracking north or south to have a (legal?) head-on encounter with one degree course offset.
 
gismo said:
You limit it by the length of the flight (such flights can't cross airways and thus are held to relatively short lengths), and/or by the filed routes coupled with clearance times and ETEs. For example, two flights between the same two airports (in the same direction) could be allowed to be in air simultaneously if a slower aircraft departed with a significant delay after the first one's void time. Intersecting flights paths could be separated by altitude restrictions.
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That's just making Class G airspace Class E airspace.
 
gismo said:
I think Richard Bach hit the nail on the head when he described the Hemispherical Altitude rule by saying that compliance only guarantees that all mid-air collisions in cruise flight will occur at angles of less than 180 degrees.
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Right, and that makes see-and-avoid just a bit more viable.
 
dmccormack said:
...the odds of two airplanes being in the same parcel of air at the same moment is reduced if the altitudes are random, as opposed to fixed.
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That's debatable, but what's magical about "below 3,000' "?
 
gismo said:
Not if you still allow VFR flight in 1 mile, clear of clouds.
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ICAO Class E airspace is airspace that permits IFR and VFR operations and provides IFR/IFR separation, it does not specify VFR weather minimums.
 
roncachamp said:
ICAO Class E airspace is airspace that permits IFR and VFR operations and provides IFR/IFR separation, it does not specify VFR weather minimums.
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Yes...but would you want to be on an ILS with 1 sm visibility, and some idiot blundering about clear-of-clouds dodging around at 500 feet scattered? Isn't that why they establish "E to Surface" to keep those idiots away?
 
JeffDG said:
Yes...but would you want to be on an ILS with 1 sm visibility, and some idiot blundering about clear-of-clouds dodging around at 500 feet scattered? Isn't that why they establish "E to Surface" to keep those idiots away?
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There are many ILSs outside of surface areas.

If what gismo proposes for Class G airspace was done the airspace would then have the properties of Class E airspace and would be so designated. I suppose it could be established with different visibility and cloud clearance requirements than present Class E airspace but that seems very unlikely.
 
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