The hemispherical rule and altitude at pilots discretion

Bill

Bill

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Say Joe Pilot is flying somewhere, VFR on flight following at 4500 per the hemispherical rule. He's getting beat up, but about the time he decides to climb to 6500, ATC gives a traffic advisory and requests Joe to climb to 5500. Time passes, traffic passes, traffic no factor, and it's nice and smooth at 5500. Joe is only 80mi out from the destination and doesn't really want to climb to 6500 only to descend shortly, but doesn't want to go back down into the bumpy air at 4500 until necessary.

So, Joe asks ATC if he can remain at 5500, and ATC replies "Altitude at pilots discretion."

So, is it cool for Joe to continue at 5500 to his planned descent point even though that's counter to the hemispherical rule?
 
It’s a bit a gray in that the “unless otherwise authorized by ATC” can come into play. The problem with that, is the only times the controller is authorized to assign a VFR altitude in conflict with the hemispherical rule, is for VFR separation. And to be more clear, VFR aircraft separation in airspace (TRSA, C, B) that requires it. Once the aircraft leaves the airspace that requires seperation, ATC has to inform the aircraft “resume appropriate VFR altitudes.”

So if it were me and ATC said “altitude your discretion,” I’d select an altitude that complies with the hemispherical rule.
 
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I agree this is a bit gray. If you really wanted to stay at 6500, you could make it less gray by not asking ATC - and simply continue to follow the last instruction they gave you, which was to maintain 5500. I'm not saying that's better or safer, but if for any reason this was going to be looked into, you'd have a better case.

It's easier IFR. All altitudes are explicit, either one specific altitude or a block altitude where you can climb and descend within that block as you see fit.

From a safety perspective, keep in mind that there are transponder-less aircraft out there. There is no absolute guarantee, but the idea behind the hemispheric altitude rules is to make a collision less probable. The longer you deviate from that rule on a VFR flight, the higher the risk (time of exposure). We can argue about whether 80 miles is long enough to worry about it or not.

- Martin
 
Bill Jennings said:
Say Joe Pilot is flying somewhere, VFR on flight following at 4500 per the hemispherical rule. He's getting beat up, but about the time he decides to climb to 6500, ATC gives a traffic advisory and requests Joe to climb to 5500. Time passes, traffic passes, traffic no factor, and it's nice and smooth at 5500. Joe is only 80mi out from the destination and doesn't really want to climb to 6500 only to descend shortly, but doesn't want to go back down into the bumpy air at 4500 until necessary.

So, Joe asks ATC if he can remain at 5500, and ATC replies "Altitude at pilots discretion."

So, is it cool for Joe to continue at 5500 to his planned descent point even though that's counter to the hemispherical rule?
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I don't see much grey area here. "Altitude at pilot's discretion" puts the ball in your court. You need to figure out the altitude appropriate for the airspace, visibility and your course. If there is a restricted airspace in front of you that tops out at 6000 ft, are you still going to go through it because ATC said altitude is at your discretion?

You didn't say what airplane you are flying, but 1000 ft climb should take about a minute, while the 80 miles takes about half an hour. It would have been an easy decision for me to climb to 6500 ft, for smoothness, regulatory compliance and for the extra safety factor.
 
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Not to be pedantic (this is totally pedantic...) but it depends on ground level too. Hemispheric rule only applies over 3,000’ AGL.

I always put this one in the “rule of thumb” / “strong suggestion” category. I don’t ignore it, certainly, but could you really get violated for flying at the wrong thousand-foot interval under VFR rules?

Edit: Looks like the FARs are pretty clear - “shall maintain” blah blah doesn’t leave a lot of room for interpretation. Well, I learned my new thing for the day, might as well go back to bed.
 
AA5Bman said:
Not to be pedantic (this is totally pedantic...) but it depends on ground level too. Hemispheric rule only applies over 3,000’ AGL.

I always put this one in the “rule of thumb” / “strong suggestion” category. I don’t ignore it, certainly, but could you really get violated for flying at the wrong thousand-foot interval under VFR rules?
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That's the other confounding factor I'll throw in. After the traffic had passed, the area Joe was traversing had terrain 2800-3200ft msl. While he could have certainly descended to 4500 and had plenty of VFR terrain clearance, he certainly was not 3000ft AGL. Just after the higher terrain, the terrain dropped to 1000msl, but that also nearly coincided with the VDP anyway.
 
Flying in the SF Bay area, I once heard ATC ask a guy who was on flight following to explain why he wasn’t flying at a legal VFR altitude for his direction of flight. They do notice.

I interpret pilot’s discretion as still being subject to the FARs.
 
I'm not an ATC. Not IFR rated. Not a lot of experience on flight following, but a bit. Disclaimers done.
Bill Jennings said:
Say Joe Pilot is flying somewhere, VFR on flight following at 4500 per the hemispherical rule. He's getting beat up, but about the time he decides to climb to 6500, ATC gives a traffic advisory and requests Joe to climb to 5500.
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I have never received a "request" to climb from ATC. I have received recommendations and instruction though. One of those is mandatory. If a a "request" is an instruction, it is mandatory. I've personally only received instructions when on flight following when in or around B, C, or D airspace.
Time passes, traffic passes, traffic no factor, and it's nice and smooth at 5500.
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When I have personally been in this situation, I hear, "resume own navigation," "altitude your discretion," "maintain VFR at or [above/below] xx00'" of some combination. None of those are instructions to fly at a certain altitude.
Joe is only 80mi out from the destination and doesn't really want to climb to 6500 only to descend shortly, but doesn't want to go back down into the bumpy air at 4500 until necessary.

So, Joe asks ATC if he can remain at 5500, and ATC replies "Altitude at pilots discretion."

So, is it cool for Joe to continue at 5500 to his planned descent point even though that's counter to the hemispherical rule?[/QUOTE]Based on my limited experience, it seems far fetched that this would be the only exchange with the controller. But even if it was, it doesn't sound like an authorization to deviate from a rule. More importantly, it doesn't sound like he's taking responsibility for your altitude and to clear your path. Which would make me want to look at the purpose of the rule and not running head on into opposite-direction traffic.
 
Bill Jennings said:
Say Joe Pilot is flying somewhere, VFR on flight following at 4500 per the hemispherical rule. He's getting beat up, but about the time he decides to climb to 6500, ATC gives a traffic advisory and requests Joe to climb to 5500. Time passes, traffic passes, traffic no factor, and it's nice and smooth at 5500. Joe is only 80mi out from the destination and doesn't really want to climb to 6500 only to descend shortly, but doesn't want to go back down into the bumpy air at 4500 until necessary.

So, Joe asks ATC if he can remain at 5500, and ATC replies "Altitude at pilots discretion."

So, is it cool for Joe to continue at 5500 to his planned descent point even though that's counter to the hemispherical rule?
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I'd climb to 6.5, unless I was about to enter airspace where ATC would be assigning my VFR altitude anyway (e.g. within the next 5 minutes). Even at 500 fpm, it's only 2 minutes to climb to 6.5 and avoid being a WAFDOF.

If you still have flight following, remember to advise ATC of the altitude change as a courtesy.
 
Life's too short - just climb to 6500, and then begin decent when you need.

Ideally, ATC wouldn't have forgotten about the pilot and would have given the instruction "at your discretion" without having to be asked.

As far as getting an "instruction" from ATC while VFR, I guess technically you don't have to follow it if you're not in B,C or D airspace. But why would you ask for flight following if you're not going to take their instructions?
 
Even if under ATC supervision (radar advisories), if given altitude discretion I would simply select an altitude that comports with the hemispherical rule to minimize potential conflicts with traffic that is not under ATC supervision. The amount of time invested to climb 1000 feet to do so is insignificant, and significantly enhances safety.
 
WDD said:
But why would you ask for flight following if you're not going to take their instructions?
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To have an extra set of eyes watching you, as well as receiving traffic advisories.
 
Why have eyes watching you if you don’t follow what they say? If I ask for their time - which they don't have to give for VFR - then I should respect their effort and work with them to keep things from bumping into each other.

Just my opinion.
 
jimhorner said:
Flying in the SF Bay area, I once heard ATC ask a guy who was on flight following to explain why he wasn’t flying at a legal VFR altitude for his direction of flight. They do notice.

I interpret pilot’s discretion as still being subject to the FARs.
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They gave me a reminder in the same area when I got momentarily confused about which altitude I should be flying.
 

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Unless I can’t maintain the VFR hemispheric altitudes, I want to be there, because that’s where I’m expected to be. A while back, I was coming home from HYI with flight following and couldn’t make a legal hemispheric altitude due to cloud bases, so I just advised ATC where I was and why I was there. They were happy with that.

Descending 1K wasn’t a sound option either due to towers.
 
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David Megginson said:
WAFDOF
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I had to look that one up - good one! I learned something today.

Is Joe gonna get sent to the FSDO for flying westbound at 5,500? Maybe not. Probably not. Is it safer to climb and fly westbound at 6,500? Yeah, probably.

By the way, Joe Pilot is an awesome name. I mean, he doesn't even have to wear his lift equation t-shirt on the ramp for people to know he's a pilot... all he has to do is introduce himself as Joe Pilot!
 
Bill Jennings said:
So, Joe asks ATC if he can remain at 5500, and ATC replies "Altitude at pilots discretion."
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Flight following is not a clearance. If ATC says altitude your discretion, it just means you're not going to gum up their works if you climb or descend so they don't really care what you do. But that doesn't give you pass to violate the rules. It just means if you bust a rule, its on you not them.

That being said, I'm struggling to remember a time when I got an altitude change from ATC while on flight following. I won't say they've never given me one, but if they did, I don't recall. Vectors for traffic? Sure. Altitude change? Not that I recall.
 
Palmpilot said:
If you're in communication with ATC, according to the FAA you also have to follow their instructions in class E airspace.

https://www.faa.gov/about/office_org/headquarters_offices/agc/practice_areas/regulations/interpretations/Data/interps/2013/Karas - (2013) Legal Interpretation.pdf
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Agree, and in this case ATC asked Joe to climb to 5500 to resolve a potential traffic conflict. Joe told me he was flying a heading of 330, the conflicting traffic was at 4500 flying heading of 200.
 
Juliet Hotel said:
Flight following is not a clearance. If ATC says altitude your discretion, it just means you're not going to gum up their works if you climb or descend so they don't really care what you do. But that doesn't give you pass to violate the rules. It just means if you bust a rule, its on you not them.

That being said, I'm struggling to remember a time when I got an altitude change from ATC while on flight following. I won't say they've never given me one, but if they did, I don't recall. Vectors for traffic? Sure. Altitude change? Not that I recall.
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I've received an altitude change request when on FF from KMCO. Lots of traffic around Orlando. The request was temporary to ease some traffic deconfliction. No biggie.
 
I had this happen to me last weekend. Cruising at 9.5k and another on IFR at 9k. ATC asked if IFR could climb for separation and for whatever reason could not so she asked me if I could drop to 8.5k for separation which I gladly did. After I saw we were clear of each other I just contacted ATC and let her know I was going down to 7.5k and was a non issue. If ATC says to go to 8.5k and maintain until further instructions then do what they request. If they give you an altitude for separation I would get back to correct VFR altitude for direction of travel as soon as safe to do so but I would advise ATC what you are doing that way everyone is on the same page. As Martin said, the longer you stay at the wrong altitude for direction the more risk there is.


Sent from my iPhone using Tapatalk
 
Juliet Hotel said:
That being said, I'm struggling to remember a time when I got an altitude change from ATC while on flight following. I won't say they've never given me one, but if they did, I don't recall. Vectors for traffic? Sure. Altitude change? Not that I recall.
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It’s not necessarily an altitude change, but rather a request to stop climbing and maintain X altitude for traffic. Once traffic becomes no factor, ATC just says ‘VFR altitude your discretion’. This is all while flying in E airspace.
 
Deelee said:
By the way, Joe Pilot is an awesome name. I mean, he doesn't even have to wear his lift equation t-shirt on the ramp for people to know he's a pilot... all he has to do is introduce himself as Joe Pilot!
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But his name could cause quite a bit of confusion in the harbour. :)
 
Juliet Hotel said:
That being said, I'm struggling to remember a time when I got an altitude change from ATC while on flight following. I won't say they've never given me one, but if they did, I don't recall. Vectors for traffic? Sure. Altitude change? Not that I recall.
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The few times I have been on FF going between Tampa and Orlando they have wanted me at or below 3500, even if I started higher. This was not inside either Bravo.
 
One of my previous partners in my now thankfully sole-owned airplane had pretty much every "hazardous attitude" there was as a pilot, unfortunately. He'd routinely fly at whatever altitude he jolly well felt like, and there were many times if we were on flight following where approach would chirp up, "MothMuncher 007, say altitude" when he was tooling around at 4000' instead of 3500' or 5500'... I think they do care. To me, "altitude at your discretion" just means select an appropriate VFR altitude.
 
MuseChaser said:
One of my previous partners in my now thankfully sole-owned airplane had pretty much every "hazardous attitude" there was as a pilot, unfortunately. He'd routinely fly at whatever altitude he jolly well felt like, and there were many times if we were on flight following where approach would chirp up, "MothMuncher 007, say altitude" when he was tooling around at 4000' instead of 3500' or 5500'... I think they do care. To me, "altitude at your discretion" just means select an appropriate VFR altitude.
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Glad you're sole owner now. So many different questions...

Can ATC tell you what altitude to fly VFR in class E? No.

Does ATC have to continue providing flight following if you're acting like a dork? No (they don't have to keep providing it, period).

Is it good airmanship to fly the wrong altitude for direction of flight when there's no strong reason to do so? No (see "acting like a dork," above).

Is it good airmanship to ignore ATC altitude requests when you're talking to them outside airspace where they can give you mandatory instructions? No (again, see "acting like a dork," above).
 
Deelee said:
I had to look that one up - good one! I learned something today.

Is Joe gonna get sent to the FSDO for flying westbound at 5,500? Maybe not. Probably not. Is it safer to climb and fly westbound at 6,500? Yeah, probably.

By the way, Joe Pilot is an awesome name. I mean, he doesn't even have to wear his lift equation t-shirt on the ramp for people to know he's a pilot... all he has to do is introduce himself as Joe Pilot!
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Is Joe Pilot related to Joe Bag-of-donuts?
 
I have been assigned wafdof by atc several times....but then it's their idea and not mine (ie it's ok when they need it!) ps not all atc is familiar with the term, I found out.
 
Let'sgoflying! said:
I have been assigned wafdof by atc several times....but then it's their idea and not mine (ie it's ok when they need it!) ps not all atc is familiar with the term, I found out.
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While on flight following or while under a clearance i.e. in controlled airspace or while IFR?
 
David Megginson said:
Glad you're sole owner now. So many different questions...

Can ATC tell you what altitude to fly VFR in class E? No.
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Why not?
Is it good airmanship to fly the wrong altitude for direction of flight when there's no strong reason to do so? No (see "acting like a dork," above).
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Not good airmanship and not legal.
 
David Megginson said:
Can ATC tell you what altitude to fly VFR in class E? No.
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They absolutely can and the pilot would be wise to comply. If you are unable (i.e. clouds), you should advise. If you simply don’t want to, you’d need to terminate flight following while complying till that’s completed.

Please read what @Palmpilot posted above. It addresses it very clearly.
 
TCABM said:
Unless I can’t maintain the VFR hemispheric altitudes, I want to be there, because that’s where I’m expected to be. A while back, I was coming home from HYI with flight following and couldn’t make a legal hemispheric altitude due to cloud bases, so I just advised ATC where I was and why I was there. They were happy with that.

Descending 1K wasn’t a sound option either due to towers.
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This is what I do. I am on FF 99% of the time. I have been known to hang out at even altitudes due to cloud bases and I just ask ATC of I can stay there and be out of the way of their IFR traffic. They've never had a problem with it. Am I going to pilot jail? Doubt it.
 
The solution for Joe Pilot is obvious. In order to stay at 5,500 he must simply turn around 180 degrees and get to his destination via Iceland, the Uk, Eastern Europe, Russia, China, Hawaii direct destination. I don’t see what the problem is.
 
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