How cloud layers affect VFR cruising altitude

11 Answers

1. 
   

   
   

   MaggotCFII on Feb 11, 2011

   In the Class E you would have to operate per FAR 91.155 Basic VFR weather minimums.
   FAR 91.159 VFR cruising altitude or flight level applies if you are flying “VFR in level cruising flight”.
   “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, maintain the altitude or flight level assigned by ATC.] [(c) Removed.] Amdt. 91-276, Eff. 1/26/2004″
   So, if you are out in the practice area and maneuvering 91.159 would not apply.
   If your Class D was VFR with your scattered clouds, you would still have to observe the 91.155 Basic VFR weather minimums.  And if you were heading into Class G then during the day your requirement would be 1 statute mile and clear of clouds.  If you want to stay in the traffic pattern, add 500′ to the TPA to stay legal.
   By the way you may hear of 91.159 referred to as the “Hemispheric Rule” (ancient history).

   0 Votes 0 Votes  0 Votes

2. 
   

   
   

   Micah on Feb 11, 2011

    I think this answers your question(s) in the way I understand you to be asking them:
    
   1. Yes, a VFR flight must always adhere to VFR cloud-clearance requirements; know what these are for the airspace(s) you will be flying in and plan accordingly. If you want clearance to fly at altitude irrespective of visibility and cloud-clearance then you must obtain an IFR clearance.
   2. Choose an altitude that accommodates both the cloud-clearance requirements and your plan of action. If this changes enroute then make the appropriate altitude/flight plan changes and advise ATC (except in those airspaces where you need clearance first).

   +2 Votes 2 Votes  0 Votes

3. 
   

   
   

   Flight Student on Feb 11, 2011

   I supposed I asked too many questions there and my real question got convoluted.
   If I’m flying along at 6,500 feet and come upon a layer of clouds, If I choose to descend, would I have to descend to 4,500 feet in order to comply with cloud requirements and VFR cruising altitude?
   I suppose if you choose to descend to avoid the cloud layer and maintain vfr cruising altitude, you’d usually have to descend 2,000 feet lower.

   0 Votes 0 Votes  0 Votes

4. 
   

   
   

   Flight Student on Feb 12, 2011

   Also, would it be possible for ATC to determine IF you were complying with the cloud requirements? 

   0 Votes 0 Votes  0 Votes

5. 
   

   
   

   Kent Shook on Feb 12, 2011

   Flight Student,
    
   ATC can’t see the clouds – In fact, occasionally when I’m IFR I’ll get a traffic call and I’ll have to tell ATC that I’m in IMC and can’t see anyone.
    
   That said, like most of the FAR’s, this rule is written in blood. This isn’t about whether you’ll get in trouble – It’s about whether you’ll be able to see an aircraft coming out of that cloud in time to avoid hitting it. Contrary to popular belief, ATC does NOT have to separate IFR aircraft from VFR aircraft. ATC’s function is to separate IFR aircraft from IFR aircraft, period – Everything else is “workload permitting.” So, you need to stay away from those clouds!
    
   It shouldn’t be that difficult (or to use your word, “taxing”) to do so – If there’s a ceiling around 7000 MSL, you should probably simply choose to cruise at 4500 MSL rather than 6500 MSL (westerly) because cloud heights are rarely perfectly even, nor are they always well-defined. 
    

   0 Votes 0 Votes  0 Votes

6. 
   

   
   

   Thomas Vaillencourt on Feb 12, 2011

   Short answer, If cruising 6,500 it is assumed you are doing so because your Magnetic course is between 180 and 359 degrees. If your course does not change, (to 0-179 degrees) then yes you would descend a full 2000 feet to maintain both the “even thousand plus 500′” and the required (Minimum) 500′ below clouds. You have to comply with both 91.159 and 91.155.

   0 Votes 0 Votes  0 Votes

7. 
   

   
   

   Thomas Vaillencourt on Feb 12, 2011

   Additionally, to answer your specific question, “Do I have to keep the required distance minimums from ALL clouds whether it be scattered or few…or those that just constitute a ceiling (broken or overcast)?” The answer is YES!  All clouds must be given the minimum clearances defined in 91.155. Whether it is several clouds, or a single cloud in an otherwise flawless blue sky. If you can’t see right through it, than you must steer clear. 

   +1 Votes 1 Votes  0 Votes

8. 
   

   
   

   Jim Foley on Feb 12, 2011

   One more addition:  In your example, the simple answer weould be yes, decend 2,000.  But what if you have a good tail wind higher up, and you want to stay right at the 500′ range.  Ask ATC if you could get a block altitude.  Workload permitting, they might be able to give you 4,500′-6,500′, so that you have the choice of what altitude your at, with out having to advise them everytime you change, and you wouldn’t have to worry about cruising altitudes.  I’m not sure what part of the country your flying in, but here in the mid-west where theres not as much traffic, I normally have no trouble getting a block.  If your in California or in the North-East, might be alot more difficult.  Can’t hurt to ask!

   0 Votes 0 Votes  0 Votes

9. 
   

   
   

   Thomas Vaillencourt on Feb 13, 2011

   This assumes you are flying at an assigned altitude, as you would under IFR.  Most VFR flying, even with flight following, you can choose your altitude at will, with flight following however it is always desired that you announce your intentions to ATC.

   0 Votes 0 Votes  0 Votes

10. 
    

    
    

    Jason Breeland on Jan 02, 2012

    I have been wondering about a related question; What if a cloud layer develops below cruise altitude and is between you and your final destination?  Is there an exception to this rule when flying VFR?  

    0 Votes 0 Votes  0 Votes

11. 
    

    
    

    Thomas Vaillencourt on Jan 03, 2012

    Short answer – No. You are still required to maintain the cloud clearance requirements prescribed for the airspace classification in which you are flying. These are prescribed in 14CFR 91.155.
    But there are ways to get down; you can find a hole in the layer through which you could visually descend (while still maintaing cloud clearances required, or if properly equipped and rated, you could request a pop-up IFR clearance to your destination. However you must keep in mind that you either need to have the proper approach plates for your destination, or if the destination is reporting VFR, than you can cancel IFR once below the clouds again.
    You could also ammend your plans and fly to a destination not obscured by a layer of clouds,
    Or in the case of very limited options, such as not having the fuel on board to reach any other destination, you could swallow your pride, declare an emergency and hope ATC can get you down using radar vectors, or
    However some food for thought:
    1. Cloud layers do not usually develop so rapidly that the decision to turn around or get under would suddenly become unavailable.
    2. Before your flight – Know the forcast weather along your route as well as at your destination, and study not just the forcast, but the trending weather patterns for your route over the previous hours before your flight.
    3. If you are unsure, ask flightwatch (122.0 most places) for a weather update along your route, and notify them the weather you are experiencing if it was not forecast. they may be able to help you find a hold or area of VFR to the ground.
    4. Most important: Although “VFR over the top” is legal, If you do not know where the holes or edges of the cloud layer are, and whether or not you can reach them, than attempting to traverse an undercast is pretty reckless.

    +2 Votes 3 Votes  1 Votes