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Is wind taken into account when calculating VFR cruising altitudes?

Asked by: 8008 views FAA Regulations, General Aviation, Student Pilot

I have a question about VFR cruising altitudes.  When you calculate your VFR cruising altitude, do you take into account wind correction angle? 

For example, if I plotted a course and found my true course (i.e.-the line I drew on the map) to be 010 degrees.  Then, I added or subtracted the magnetic variation (isogonic line value) and found that my "magnetic course" (or is this called magnetic heading?) to be at 005 degrees.

THEN, I determined my wind correction angle was -7...so my "true heading" (the direction I point the nose of the aircraft) was 358 degrees.  So, my heading indicator will read 358 degrees in order to fly to my destination.

HOWEVER, since my groundtrack (i.e. - magnetic value of true course+isogonic line) was 005 degrees, wouldn't I STILL fly at odd+500 foot altitude since my groundtrack (005 degrees) is East...even though my nose (358 degrees) is pointed more West?

My question therefore is do VFR cruising altitudes take into account WCA?

If the wind changes during flight, this could produce a major headache in flight planning if you have to keep changing altitudes based upon WCA.

If it is based on COURSE and not on WIND...I'm wondering why the directions on my flight planning sheet and the back of the E6B tell us to calculate true course...THEN WCA...THEN magnetic variation.  You may calculate the same heading to fly, however, shouldn't you want to calculate magnetic variation PRIOR to WCA in order to determine your cruising altitude?  I.E. - See instructions below:

TC (plus or minus) WCA = TH (plus or minus) VAR = MH (plus or minus) DEV = CH

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2 Answers

  1. Best Answer


    Kent Shook on Oct 29, 2010

    No – VFR Cruising altitudes are based on your magnetic course. This can be found in FAR 91.159:

    § 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).”

    So, in your example above, with your heading at 358 but your magnetic course at 005, you do have an eastbound magnetic course and should fly an odd altitude plus 500 (3500, 5500, 7500, etc).

    As for flight planning, the reason you calculate things in that order is that winds aloft are given relative to true north (ref: AC 00-45G, Aviation Weather Services, section 7.4.2 at http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgAdvisoryCircular.nsf/0/d6a522c25e53cbf58625776f0050495c/$FILE/AC-0045G_chg1_fullDocument.pdf ) so you need to calculate the wind correction angle prior to converting to magnetic.

    So, to calculate the proper cruising altitude, you simply convert True Course to Magnetic Course – a simple one-step calculation using the magnetic variation on your sectional. (Remember “west is best” so add if west, subtract if east.) Then, determine your cruising altitude… And don’t forget to enjoy the flight!

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  2. Jason Schappert on Oct 30, 2010

    VFR altitudes are based on you magnetic course
    You Change True Course to Magnetic Course using the Magnetic Variation
    Jason

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