Class B Airspace Question

[Mogus]

We were flying through Las Vegas Class B Airspace today and told to "descend at your discretion." At the time we were on a heading of 190 at 6,500. I descended to 5,500 because we were getting close to our destination, Henderson, and I didn't want to make a drastic descent to get to TPA. Approach verifies we're level at 6,500. After saying we were at 5,500, the controller informs us that we're on the wrong altitude for that heading, which I was well aware of. However, I thought the VFR cruising altitudes didn't apply in Bravo airspace, when the controller says descent at my discretion. Any insight?

 

[maverick_fp00]

when you are told to descend at your discretion, that means just that, descend at YOUR discretion. those altitudes aren't mandatory, they are recommended, per say. so if you were descending through 6500 to 5500, i don't see anything wrong with that.

 

[Singlecoil]

Altitudes aren't mandatory, but I think his point was, why are you leveling off at an altitude that some other VFR guy might be flying in the opposite direction. If you aren't planning your descent for a continuous descent, then level off at 4500 instead of 5500. If the controller gets busy, he is going to pay more attention to the IFR traffic. He would like to be able to glance at the VFR's and know that they are doing just fine without him, rather than having to turn one, because opposite direction traffic was at the same altitude.

 

[Pilotadjuster]

Class B

Surprising they didn't give you an altitude to descend to. My experience has been that controllers like all their vfr traffic going in the same direction at the same altitude when under positive control in Class B.

As far as the VFR cruise altitude rules; they only apply when 2000' AGL or higher. A good rule at any altitude, but hard and fast only 2000' agl. And they normally do not apply in Class B where you are under positive control. For example, coming out of SLC Class B, they normally send you in any direction at 5,500' msl, and bring you back in from any direction at 6,000' msl.

I have heard horror stories about controllers and vfr traffic in LV class B. Most guys I know file IFR just to avoid the vfr hassles there.

 

[Checks]

91.159

Read it

 

[Toy Soldier]

Quote by Pilotadjuster
they only apply when 2000' AGL or higher. A good rule at any altitude, but hard and fast only 2000' agl.

Someone had a typo...

FAR/AIM QUOTE
§91.159 VFR cruising altitude or flight level.

Except while holding in a holding pattern of 2 minutes or less, or while turning, each person operating an aircraft under VFR in level cruising flight more than 3,000 feet above the surface shall maintain the appropriate altitude or flight level prescribed below, unless otherwise authorized by ATC:

Also, I do extensive flight in and around Class B and have had the following experiences:

1. ATC will assign me an altitude.
2. ATC will ask me what my desired altitude is and then they allow it when/if able.

I have never been told to descend NOR climb without having "requested/been assigned" an altitude. This has been my experience...

 

[Pilotadjuster]

Class B

I stand corrected. Sunday morning fuzz...

Sec. 91.159

VFR cruising altitude or flight level.

Except while holding in a holding pattern of 2 minutes or less, or while turning, each person operating an aircraft under VFR in level cruising flight more than 3,000 feet above the surface shall maintain the appropriate altitude or flight level prescribed below, unless otherwise authorized by ATC:
(a) When operating below 18,000 feet MSL and--
(1) On a magnetic course of zero degrees through 179 degrees, any odd thousand foot MSL altitude +500 feet (such as 3,500, 5,500, or 7,500); or
(2) On a magnetic course of 180 degrees through 359 degrees, any even thousand foot MSL altitude +500 feet (such as 4,500, 6,500, or 8,500).
(b) When operating above 18,000 feet MSL to flight level 290 (inclusive) and--
(1) On a magnetic course of zero degrees through 179 degrees, any odd flight level +500 feet (such as 195, 215, or 235); or
(2) On a magnetic course of 180 degrees through 359 degrees, any even flight level +500 feet (such as 185, 205, or 225).
(c) When operating above flight level 290 and--
(1) On a magnetic course of zero degrees through 179 degrees, any flight level, at 4,000-foot intervals, beginning at and including flight level 300 (such as flight level 300, 340, or 380); or
(2) On a magnetic course of 180 degrees through 359 degrees, any flight level, at 4,000-foot intervals, beginning at and including flight level 320 (such as flight level 320, 360, or 400).

 

[midlifeflyer]

Re: Class B

Sec. 91.159

VFR cruising altitude or flight level.

Thanks for posting the text.

Notice: there's no exception for Class B or C airspace. Unless you are given a hard altitude by ATC, you are expected to fly in accordance with the rule.

So, back the original post. You were at 6500. ATC knew you were going to Henderson and that the airspace in front of and below you didn't present a conflict for a descent. So you were cleared to descend at your discretion rather than being given a series of hard altitudes. Perhaps unusual in some parts of the country but certainly not in others.

For practical purposes, all it meant is that you had permission, at least from an altitude standpoint, to do what you could have done if you were not in Class B.

 

[SierraPilot]

Now a question for the CFI's... when your with a student VFR, and your practicing manuvers above 3000.. since your constantly changing directions... what altitude do you use as the deciding factor ? Just curious

Ryan

 

[Toy Soldier]

SierraPilot

A good question. Here is one answer. I'm sure that you will get a few differing versions as well from others.

Post by SierraPilot
since your constantly changing directions... what altitude do you use as the deciding factor ?

FAR/AIM RULE
Except while holding in a holding pattern of 2 minutes or less, or while turning, each person operating an aircraft under VFR in level cruising flight more than 3,000 feet above the surface.

The key verbage in the FAR/AIM quote is "while turning" and "level cruising flight". Those pilots maneuvering and not in level cruising flight are "exempted" from the rule.

Also:

The PTS requires that the ground reference maneuvers
enter at 600 to 1000 AGL while steep turns, slow flight, stalls
require 1500 AGL.

Therefore, maneuvers are typically performed below 3000' AGL anyway. Maneuvers aren't usually practiced above that altitude. However, I usually take my students up to 3500 feet or higher for stalls. Simply because I have been "snapped" into a spin once or twice before...

I hope this helps.