VFR on TOP

[zbwmy]

Here are two scenarios I would like imput on from my brothers on the other side of the mic:

1.) Cruising VFR on top between point A and point B via direct routing. Are you authorized to fly below the MIA (minimum IFR altitude) for that route segment to remain clear of clouds? If your answer is yes, where are you getting the MIA data? Sectional, L chart, Jep, ect..?

2.) Depart ACK IFR climbing to 160 with the preferred routing to HPN. (OPT and LXJ pilots the preffered route is NOT ACK..HPN)
Request and receive VFR on top. Does this clearance allow you now proceed VFR to HPN?

MY Boston Center

 

[SPilot]

http://www.faa.gov/ATpubs/AIM/Chap4/aim0404.html#4-4-7
-Scroll down to 4-4-7

e. When operating in VFR conditions with an ATC authorization to "maintain VFR-on-top/maintain VFR conditions" pilots on IFR flight plans must:​

1. Fly at the appropriate VFR altitude as prescribed in 14 CFR Section 91.159.​

2. Comply with the VFR visibility and distance from cloud criteria in 14 CFR Section 91.155 (Basic VFR Weather Minimums).​

3. Comply with instrument flight rules that are applicable to this flight; i.e., minimum IFR altitudes, position reporting, radio communications, course to be flown, adherence to ATC clearance, etc.​

#1
My interpretation is: no. Because you still have to comply with IFR rules, and you're on IFR flight plan. Usually I wanna be as high as I can, and the cumulus clouds are usually at lower altitudes, so generally speaking it is uncommon to have to descend to maintain VFR during cruise at 10-12.000'. It all depends though...
"Minimum IFR altitude" is a bit unspecific: for IFR-flights we get "Minimum Enroute Altitude" from our low altitude enroute chart (IFR-chart), and altitudes for VFR flights can be read as "Maximum Elevation Figure" within quadrants of our Sectional Charts (VFR-chart). Minimum Off-Route altitudes for IFR are most easy to read on approach plates as the Minimum Safe Altitude within usually 25NM of an airport.

#2
I think this paragraph is the most suitable one to answer your question:

f. ATC authorization to "maintain VFR-on-top" is not intended to restrict pilots so that they must operate only above an obscuring meteorological formation (layer). Instead, it permits operation above, below, between layers, or in areas where there is no meteorological obscuration. It is imperative, however, that pilots understand that clearance to operate "VFR-on-top/VFR conditions" does not imply cancellation of the IFR flight plan.

In other words: if obtaining an VFR on Top Clearance, it does NOT cancel or amend the IFR clearance. So even with VFR on top, the pilot will still need to hear "Cleared to HPN via Victor XXX | radar vectors | direct" before proceeding beyond their clearance limit.

VFR on top is simply just a clearance to maintain different altitudes, so that the flight crew can maintain aircraft control visually, and the aircraft may remain outside of visible moisture. If flying close to towering cumulus, it will often be a much smoother ride if the airplane maintains altitudes just at the top of the "exploding clouds" and deviates slightly to avoid flying right through the rising column of air.

If the weather permits proceeding to destination VFR, then I'd cancel IFR alltogether and proceed direct. I'm sure many people disagree, but when flying General Aviation airplanes, it is not very much point in being on IFR clearance if the weather is all clear. So to cancel IFR is a good call!
​

 

[A Squared]

1.) Cruising VFR on top between point A and point B via direct routing. Are you authorized to fly below the MIA (minimum IFR altitude) for that route segment to remain clear of clouds? If your answer is yes, where are you getting the MIA data? Sectional, L chart, Jep, ect..?

Your question appears to ask if you can operate below the MIA to avoid clouds, let's make it two questions:

1A) may you operate below the MEA, (or MIA when off route.)

1B) may you descend below the MEA or MIA to maintain cloud clearences with a cloud which is at or below the MEA/MIA?


If operating under part 135 or part 91 only, no to both questions. You must remain above whatever minimum altitude would apply, MEA on the airways, MIA off the airways.

If you are operating under Part 121 the answer to question 1A is yes and the answer to question 1B is no. This is a very rare case of 121 operations being less restrictive than 135 or 91. Under Part 121 you may descend below the MEA on a "VFR on TOP" clearence, however any ceiling must be at least 1000 ft above the appicable MEA, in other words you must be able at all times to climb in the clear to the MEA, plus 500 ft for a VFR altitude and be able to maintain VFR clearence with the clouds. SO, under 121, you can descend below the minimum IFR altitude, but you can't do it to avoid clouds.

2.) Depart ACK IFR climbing to 160 with the preferred routing to HPN. (OPT and LXJ pilots the preffered route is NOT ACK..HPN)
Request and receive VFR on top. Does this clearance allow you now proceed VFR to HPN?

MY Boston Center

Absolutely not, the VFR on TOp clearence has no effect on your cleared route, you are still required to follow the your cleared routing.

Now you may be able to get cleared for a different route whrn VFR on top. I have encountered situations when I could not get a direct clearence when at an assigned altitude, but when I was cleared VFR on Top, the controller was able to clear me for hte requested route. May not work in areas of preferred routing though.

 

[siucavflight]

No, both IFR and VFR rules apply. You must pick an approiate VFR altitude(odd, even plus 500) but that altitude must be at or above the MIA, and the data will come from your L chart.