Sport Pilot Talk

We're told that ... "each person operating an aircraft under VFR in level cruising flight more than 3000 feet above the surface shall maintain the appropriate altitude "...

I can't find where this has been hashed around before, so here's my question.
3000 feet above which surface?
The surface directly beneath you at any given time?
Or, I've thought possibly it was the surface shown as the MEF on the appropriate sectional (maximum elevation figure) but that number is determined by the highest "feature" in that particular quadrangle which can be the tops of trees, towers, antennas, etc.
If it's the surface directly below you and you want to cruise just below 3000 feet AGL, I would think one would stay pretty busy (at least in the western states).

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And, as you're flying along, particularly in the western states, do you keep tabs on the ground elevation so you know you're less than 3000 feet?

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My EFIS displays AGL altitude.

I used to fly at appropriate VFR altitudes in my Skyhawk but in my CT most of the time it is too much work and too much of a roller coaster ride. The 10,000' limitations tends to keep me within 3,000' most of the time anyway.

I would guess there is at least some horizontal leeway, at least the 2,000 feet mentioned for minimum safe altitude. I would think they would rather have you flying at a somewhat consistent level than jumping all over the place. I personally give myself and 3-5 minute circle where I figure AGL. In the mountainous West, the terrain underneath could vary an easy 5,000 feet in 5 minutes of flight. I'm not flying that roller coaster...
Here's a common half-hour breakfast flight... horizontal profile at bottom.

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[drift]Tim, is that Foreflight?[/drift]

Looks to me like WingX. They're pretty similar. (I'm sure Hilton Goldstein cringes when I say that.)

I'm not arguing or trying to stretch the FAR's. I think it's just one of those "technicalities" and there's very little concern for this in most of the eastern states. However, as has been mentioned, it's quite a roller coaster to comply with in lots of areas and really isnt relative at all to the 10000 foot rule, as this applies everywhere regardless of elevation.
An example is a 7500 MSL area of the Mogollon Rim in Arizona where one could be cruising southwesterly at 2000 AGL and very quickly be over a vast area that's only 5000 MSL. Now you're 4500 AGL but heading the wrong direction for VFR cruising, and you've technically busted the east - west altitude requirement.
I've not heard of anyone getting busted for something like this, so there must be some "leeway" since you're showing up on radar as not complying.

The hemispheric rule is not really regulatory, so much as a recommendation. I believe it is found in the AIM, not the FARs.

FAR 91.159 VFR Cruising Altitude or Flight Level

I quoted part of it in my first post ..... "each person operating an aircraft under VFR in level cruising flight more than 3000 feet above the surface shall maintain the appropriate altitude ... "

Also please note it says "shall" and refers to "surface", not ground. Hence, the question.

drseti wrote:The hemispheric rule is not really regulatory, so much as a recommendation. I believe it is found in the AIM, not the FARs.

As dwayne pointed out, one of those rare occasions the professor is wrong.

Mark the date and time, it may be a one time occurrence!

BTW, this came up on the Cirrus Owner's site recently, when a newly minted pilot told us he liked to choose "off" altitudes, thinking it reduced his midair chances. He said he figured that when he announced he was cruising at 7,200', for instance, and ATC did not take issue, it meant it was fine.

Needless to say, we pounced and pointed out to him the error of his ways.

Thanks for correcting.me,.Dwayne (and for rubbing it in, Eddie!)