John Collins
En-Route
WAY,
IF YOU HAVE NO OTHER INFORMATION!!!!!!!!!!!!!
IF YOU HAVE NO OTHER INFORMATION!!!!!!!!!!!!!
Airways vs direct
- Thread starter ChrisK
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dtuuri
Final Approach
But you're supposed to have the information before you request the route. Do you not plan your flights?
dtuuri
midlifeflyer
Touchdown! Greaser!
AIM 5-3-4. a(3)(b):Pasted from AIM 5-1-8 c. 4. on the FAA's website just now:
Increasing use of self-contained airborne navigational systems which do not rely on the VOR/VORTAC/TACAN system has resulted in pilot requests for direct routes which exceed NAVAID service volume limits. These direct route requests will be approved only in a radar environment, with approval based on pilot responsibility for navigation on the authorized direct route. Radar flight following will be provided by ATC for ATC purposes.dtuuri
Unpublished RNAV routes are direct routes, based on area navigation capability, between waypoints defined in terms of latitude/longitude coordinates, degree-distance fixes, or offsets from established routes/airways at a specified distance and direction. Radar monitoring by ATC is required on all unpublished RNAV routes, except for GNSS-equipped aircraft cleared via filed published waypoints recallable from the aircraft's navigation database.
And, thanks John -
Controller's Handbook 4-4-1
c. Random routes.
1. When not being radar monitored, GNSS-equipped RNAV aircraft on random RNAV routes must be cleared via or reported to be established on a point-to-point route.
Controller's Handbook 4-4-2:
h. Provide radar monitoring to RNAV equipped aircraft transitioning via random RNAV routes.
EXCEPTION. GNSS equipped aircraft /G, /L, /S, and /V not on a random impromptu route.
(apparently there is a difference between a planned route and a shortcut in flight)
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RotorDude
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It is practically impossible to pre-plan all the possible detours you might encounter on a real trip. You might get a detour due to traffic or weather, and then be cleared direct to the next fix, or a subsequent one. You can't possibly predict this before launching, and therefore the only logical way to conform to lost comms is to check the OROCA (or onboard equivalent, e.g. Garmin GTN shows MSA for the route, plus the obstructions/terrain are color coded).
Edit: BTW, this might happen (and does happen) even on a non-RNAV flight, so the above is still applicable, as is the impracticality of "pre-planning" in this context.
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What if you can't make the OROCA? What if you are relying on mountain passes to get through? I think it's funny that there are people who don't make use of a terrain database we spent billions to develop. That was one of the great contributions of the Space Shuttle, doing the mapping work for our terrain/SVT database. If you don't use it, you make a great asset in navigational safety into a waste of tax money.
dtuuri
Final Approach
How do you explain the fact that 91.185 pre-exists OROCA? Are you saying it was never viable? My point is, under the new system 91.185 needs to be changed for all the reasons you stated. Under the old one (and the current one using GPS sans radar--see Midlifeflyer's post above), you planned the direct portions prior to takeoff. Vectors off route are covered in 91.185. Pilot requests enroute for direct are assumed to be compliant w/ 91.177 in the event of lost comms. Unfortunately, there's a lot of lazy piloting going on these days.
dtuuri
azure
Final Approach
As I read it, by "no other information" John meant you are off airway and therefore have no MEA, and don't know ATC's undisclosed-to-pilots MIA. Then the OROCA applies, and should take into account obstacles like your now-dismantled TV tower. If it doesn't, then it's a charting issue and not a point-to-point vs. airway issue.
However, I tend to agree with you that if ATC still wants you high enough to be seen when on random routes, their private MIA info (or at least minimum altitudes for radar coverage) should be published or available in chart form on request. I don't know what the 7110.65 says though, I'm only going by my experience out here with ZBW, which may not apply everywhere.
dtuuri
Final Approach
Terrain's only one consideration. There's the non-radar areas you won't get to go through (unless GPS-equipped and pre-filed for that) you won't know about. There's the sector MIAs that are unpublished and could affect a pilot's altitude selection. And there's commmunications reliability--ATC won't clear you where they can't talk to you, so how do you know before you file you aren't headed for such an area?
Then there's the OROCA--I don't think ATC's gonna be happy with John Collins zoom-climbing to 9000' MSL, an OROCA set by Mt. Mitchell, when he's located 20 nm southeast of Sugarloaf Mountain, an area where an airway would have an MEA of just 3000', if he lost comms there.
Work needs to be done, I tell ya.
dtuuri
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RotorDude
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GliderDude
I am guessing that as RNAV proliferated, FAA realized that direct routing required more info to conform to 91.177 and 91.185, and therefore introduced the OROCA on the enroutes. Be that as it may, it doesn't mean we are not supposed to use OROCA today for this purpose, or that there is any way to avoid using it (or equivalent) by "pre-planning" for all possible eventualities and routings.
azure
Final Approach
I thought I'd read that somewhere. Well I am GNSS equipped, always file via published waypoints that are in the 480's database, yet ZBW has still made me choose between climbing high enough to be radar monitored and going on an airway. A few weeks ago they also withheld an IFR clearance that I tried to pick up in the air, because I couldn't maintain VFR up to an altitude where they could see me, until I agreed to go on an airway. Even then, the clearance didn't take effect until I was established on the airway.
Sure, if they can't see you, and you aren't reporting on an airway, how can they provide traffic separation?
azure
Final Approach
I assume position reporting would still be required for separation, but why would you have to be on an airway?
If that's necessary, then I don't understand why the exception Mark quoted even exists.
midlifeflyer
Touchdown! Greaser!
That they are permitted to doesn't mean that they will. There's more that goes into a clearance than what the rules allow and what we as pilots want.
dtuuri
Final Approach
I don't know where this idea originates. See my last post about the zoom climb. Remember how big an area OROCA covers? It's four times the size of an MEF on a sectional chart. Four times! It's just crazy to use that.
Controlled airspace is another thing I just thought of. Cleared "direct San Francisco" from Omaha could put you outside of controlled airspace someplace enroute, something you might not be bargaining for, not to mention a mountain. That could cause a circuitous reroute later in the flight. How's a pilot going to have the information to decline it? I know you've experienced this sort of thing before and posted about it.
dtuuri
midlifeflyer
Touchdown! Greaser!
Guess? It has more to do with the ability to obtain a guaranteed signal than anything else. Note you need radar contact for even RNAV that is not satellite based (i.e., the VOR-based King KNS 80). Victor airways guarantee a reliable VOR nav signal. They system doesn't guarantee you will always receive one off-airway.I assume position reporting would still be required for separation, but why would you have to be on an airway?
azure
Final Approach
Oh, granted. It could also be a ZBW policy that doesn't apply everywhere, which is why I put in the earlier disclaimer. Just pointing out that the exception you quoted may not help us at all depending on unknown factors -- so I agree with dtuuri that the radar coverage maps should be publicly available for help in flight planning.
dtuuri
Final Approach
They introduced OROCA at the request of the military. They also liked the MORA concept Jeppesen had been using since the 1940s. But it has nothing to do with lost comm procedures which have been in place for probably half a century before OROCA was invented. ATC panned OROCA as having any value in traffic separation and that's what 91.185 is all about.
If you have a cite for that please post it. I've never seen such a thing. Like I said before, 91.185 covers vectors off route. It's the existence of vectoring areas that enable RNAV to work, so RNAV is covered by extension.
dtuuri
azure
Final Approach
Right, but I thought we were talking about GNSS-equipped aircraft?
azure
Final Approach
I'm not sure what your point is. Again, for terrain you use the OROCA if no other information exists. Yes, it might be higher than your service ceiling in which case you need to take that possibility into account in your flight planning, or before you accept an impromptu clearance like that. And it might be that high because of an obstacle 30 nm off your route. That's an inherent limitation of sector-based minimum altitudes. With my lowly 177, if I was going to fly IFR through the western mountains, I'd insist on airway routes anyway (and be damn sure the weather was benign).
The closest thing I ever experienced to that was getting routed through a MOA that then went hot unexpectedly. Not quite the same thing. And now I usually file around MOAs and don't accept clearances through them if I'm more than a few minutes away from them.
midlifeflyer
Touchdown! Greaser!
Sorry, I thought you were asking why the exception to the radar-required rule for GNSS-equipped aircraft was written. I obviously misunderstood the question.Right, but I thought we were talking about GNSS-equipped aircraft?
John Collins
En-Route
Not going to waste my time on this anymore, and my time is not worth much.
RotorDude
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GliderDude
As I read 91.185 (which refers to MIA) and 91.177 (which defines MIA), as well as OROCA (as defined in the enroute legend), I don't see why OROCA may not be used as a minimum altitude for lost comms per 91.185(c)(2)(ii). It will not assure comms, but will guarantee obstacle clearance when losing comms.
Not sure what else is needed.
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I assume position reporting would still be required for separation, but why would you have to be on an airway?
Position reporting requires a plotted and referenced position. Calling in a lat & long along with course and speed for a controller to enter isn't likely to be happening.
dtuuri
Final Approach
The legend only says OROCA is similar to MEF, but 2000' higher in mountainous areas. Doesn't say anything about it being an MIA altitude.
Because it's way too high in many cases and isn't MIA in the first place. If it was, they'd call it so.
Preflight planning and not blindly accepting direct clearances if you don't absolutely know you can fly the whole route under lost comms.
dtuuri
dtuuri
Final Approach
Well, don't go away mad, just... never mind.Not going to waste my time on this anymore, and my time is not worth much.
dtuuri
RotorDude
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GliderDude
"OROCA- An off-route altitude which provides obstruction clearance with a 1,000 foot buffer in nonmountainous terrain areas and a 2,000 foot buffer in designated mountainous areas within the United States. This altitude may not provide signal coverage from ground-based navigational aids, air traffic control radar, or communications coverage."
(e.g. Pilot/Controller Glossary)
Per 91.177(a)(2)(i) and (ii), OROCA, as defined above, is covered by that requirement. Therefore, OROCA (in this limited context) is the applicable MIA.
"Too high" is subjective, and your last sentence, if applied, would make the FAR's near-infinite in size and therefore impractical.
Note that I do agree with you that before launching, a pilot should be aware of the general lay of the land and the highest points along the route, taking into account potential unplanned deviations. If his equipment or capabilities preclude going above the OROCA as might be needed for a possible detour, he should switch to, or at least consider, plan B.
Here we agree, per above.
dtuuri
Final Approach
I'll grant you that I should have said, "Doesn't say anything about it being an MIA altitude for the route in question, unless the route just happens to directly overfly the highest elevation within the tic lines". Any other route would be lower, possibly much lower near irregular/sloping terrain.
Why? If the aircraft can pass 91.177 muster on the route, the pilot might have good reason for going that way. OROCA is much too arbitrary and lacking in precision. Also, the pilot needs to know whether the route is viable beyond terrain avoidance off airways considering the other things I've mentioned. That information just isn't currently available for flight planning, yet alone while enroute.
I think pilots today, equipped with advanced avionics, assume these details have been dealt with and don't want to be burdened trying to figure them out for themselves. They bury their heads in the sand, buy back-up battery-operated gizmos to cover themselves and dismiss the rules and procedures established for the airway based system where direct flights are special cases instead of the norm. All I'm saying is, "The rules need updating to keep pace before somebody zooms up to OROCA through the belly of a regional jet or accepts a clearance through a distant mountain and follows 91.185 unknowingly right into it." Is that too much to ask?
dtuuri
John Collins
En-Route
With ForeFlight, one can plan a point to point route and set the lateral obstacle and terrain limits to 8 NM (+/- 4 NM) and determine the minimum IFR altitude for the route or route segment. This is an option in the profile view available to ForeFlight users. This can also done while airborne if the route changes and the MIA needs to be determined on the fly so to speak.
azure
Final Approach
Why lat long coords? Your route is defined by published waypoints. Why wouldn't "N8JT is 10 nm west of KRAZZ" work, when on a route segment from, say, SYR to KRAZZ?
dtuuri
Final Approach
That's great! Should the FAA require ForeFlight in the new point to point system? Or should the government simply do the deed before issuing the clearance, in your opinion?
dtuuri
ChrisK
En-Route
Keep in mind I certainly had foreflight, profile view, and hazard advisor running while I was confusing the controller in my scenario, but I was also VMC. Had I been in IMC at 3000' with the freezing level at 5400' I would have been much more vocal and concerned. I think John's point about using situational awareness tools for terrain and obstacle avoidance is good practice and shouldn't substitute following the rules and using one's head.
Right, but that is on an airway, not 'direct' from an unknown position direct to a point.
azure
Final Approach
I didn't think we were ever talking about a route from an "unknown position", but on a filed route between published fixes. What is your definition of an airway? That is neither a V-route nor a T-route, it's a route defined by fixes.
That's always how I file, and in fact the SYR KRAZZ route is the one I was on when I was told to climb to 11,000 or they'd reroute me onto a Victor airway.
Everskyward
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Everskyward
Are you kidding? You can insult me all you want but John Collins knows more about this stuff then the rest of us put together.
peerlesscowboy
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That's my understanding as well. A number their fledgling fighter jocks could use to avoid running into terrain when they got lost at 500 miles an hour. For the typical general aviation IFR pilot OROCA is just chart clutter.
dtuuri
Final Approach
Insult you? If I ever did it was only to return the favor. As for John, it depends on what you mean by "stuff". He's an avionics guy and extremely knowledgeable technically, including RNAV TERPs requirements. He isn't an operational type and that's where we differ in our opinions. He doesn't see any problem with dumping Victor airways, but still retaining all the rules and procedures based on them. I do. Since he bowed out, how do you feel about it? Is 91.185 due for a rewrite to support the new point to point system without many airways?
dtuuri
John Collins
En-Route
I wonder what constitutes an operational type.
dtuuri
Final Approach
It's ironic you started a thread about the exact route scenario I asked questions about when giving instrument flight tests in the past. I wanted to make sure applicants knew obstructions could (and did) exist between the airways on low altitude enroute charts. Accepting "direct" from a distant ATC facility didn't mean your route was safe or legal once beyond their jurisdiction. ForeFlight offers a way to mitigate the terrain aspect, but there are other issues as well, as I've noted.
It seems to me ATC should have the ability to ensure pilots aren't placed on any route at any altitude that they can't legally and safely fly all the way to the end in the event of lost comms. That's what children of the magenta line expect. I'm in favor of giving it to them before the FAA takes away the airway structure that offers the same.
dtuuri
dtuuri
Final Approach
I wonder what constitutes an operational type.
Somebody who flies/flew professionally and sincerely makes an attempt to comply with rules and good operating practice.
dtuuri
midlifeflyer
Touchdown! Greaser!
91.185 has arguably been due for a reality check re-write ever since radar became more prevalent than position reporting.
But that aside, I don't see where the 91.185 "route" - assigned, vectored, expected, filed - or altitude - highest of assigned, expected or regulatory minimum - require airways. Even the regulatory minimum contemplates non-published routes: the 1,000/2,000 AGL rule in 91.177(a)(2).