VFR and IFR Cruising Altitudes

What Flight Level should I cruise at?

Is Fifteen Feet O.K. for my Cruising Altitude?
Viper North owner Jeff “Biscuit” Lewis flys his Czechoslovakian designed Aero Vodochody L-29 Delfin jet at 15 feet above the deck. How’s that for a cruising altitude?

Pilots must be aware of Cruising Altitudes for both VFR (Visual Flight Rules) and IFR (Instrument Flight Rules) flight.

Automobile Analogy
Here’s a simple analogy. Car drivers know they have their own side of the road to travel on. There is even a yellow line separating the two sides of the road. Cars on each side of the road must stay on their own side to avoid a collision with oncoming traffic. Similarly, pilots use different cruising altitudes for vertical separation. These “roads” or “airways” in the sky are similar to traffic lanes to separate converging traffic.

Vertical Separation
In the air, pilots use vertical separation to help avoid collisions with other oncoming traffic. Pilots fly at different altitudes for different directions of flight. This altitude separation works like traffic lanes to keep aircraft flying in different directions from colliding into each other.

3,000 AGL
Designated Cruising Altitudes are required for flights operating at more than 3,000 feet Above Ground Level (AGL). When a pilot is operating at more than 3,000 feet above the surface, they are to fly at an altitude appropriate for their direction of flight. Airplanes flown VFR at 3,000 or less AGL are not required to fly at any particular cruising altitude.

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:

When operating below 18,000 feet MSL

• 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)
• 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)

When operating above 18,000 feet MSL, maintain the altitude or flight level assigned by ATC.

Hemispherical Cruising Altitudes

VFR Cruising Altitudes
VFR Pilots flying on a magnetic course (track) of 0 degrees through 179 degrees should fly any odd thousand foot MSL (Mean Sea Level) altitude plus 500 feet. Example VFR Cruising altitudes would be 3,500 feet, 5,500 feet, 7,500 feet etc.

VFR Pilots flying on a magnetic course (track) of 180 degrees through 359 degrees should fly any even thousand foot MSL altitude plus 500 feet. Example VFR Cruising altitudes would be 4,500 feet, 6,500 feet, 8,500 feet etc.

Vertical Separation
These VFR Cruising Altitudes provides a minimum of 1,000 feet clearance or vertical separation from other VFR airplanes heading in opposing directions.

These altitudes are based on your course or ground track, and not necessarily your heading being flown because of variance caused by cross-wind effects.

East is Odd
As a memory aid, I always think of people from out east speaking with an ‘Odd’ accent. East directions, from 0 degrees through 179 degrees represented on the right (or east) side of the diagram therefore use ODD 1,000 foot altitudes plus 500 feet. Conversely, the West directions, from 180 degrees through 359 degrees on the left (or west) side of the diagram use EVEN 1,000 foot altitudes plus 500 feet.

Who’s flying at the 1000′s?
If the VFR Pilots are cruising at the 1,000′s PLUS 500 feet, who is flying at each of the 1,000 foot levels? The IFR Pilots.

IFR Cruising Altitudes
IFR Pilots flying on a magnetic course (track) of 0 degrees through 179 degrees should fly on an odd thousand foot MSL altitude. Example IFR Cruising altitudes would be 5,000 feet, 7,000 feet, 9,000 feet etc.

IFR Pilots flying on a magnetic course (track) of 180 degrees through 359 degrees should fly on an even thousand foot MSL altitude. Example IFR Cruising altitudes would be 4,000 feet, 6,000 feet, 8,000 feet etc.

Remember, Cruising Altitudes are based on your course or ground track, and the pilot must consider cross-wind variances to their heading being flown.

Vertical Separation
These IFR Cruising Altitudes provides a minimum of 1,000 feet clearance or vertical separation from other IFR airplanes heading in opposing directions. In addition, we can see the IFR traffic is separated from the VFR traffic by minimum 500 feet.

See and Avoid
Pilots should always be actively scanning for other airplane traffic. The VFR pilot should see and avoid other air traffic. And, it is comforting to know there is a built-in vertical separation for safety based on these established cruising altitudes!

Flight Level (FL)
Sometimes altitudes in feet are abbreviated as Flight Levels. A Flight Level is a standard nominal altitude in hundreds of feet. The Flight Level altitudes are calculated from the International standard pressure datum of 1013.25 hPa (29.92 inHg), or the average sea-level pressure.  This may not be the same as the aircraft’s true altitude either above mean sea level or above ground level due to variances in atmospheric conditions (from standard pressure) where the airplane is being flown.

Flight levels are described by a number, which is this nominal altitude (“pressure altitude”) in feet, divided by 100. Therefore an apparent altitude of, for example, 35,000 feet is referred to as “flight level 350″.

Flight levels are usually designated in writing as FLxxx, where xxx is a one-to-three digit number indicating the pressure altitude in units of 100 feet.  For instance, FL200 indicates the pressure altitude of 20,000 feet. The phrase “flight level” makes it clear that this refers to the standardized pressure altitude.

At or Below 3,000
Remember, these cruising altitudes only apply to pilots operating aircraft at more than 3,000 feet AGL (Above Ground Level). Pilots operating at or below 3,000 feet AGL may fly at other altitudes. Also, these cruising altitudes do not apply when the airplane is turning or manoeuvring while practicing flight manoeuvres such as stalls, steep turns, and other activities.