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Class C service provides approved separation between IFR and VFR aircraft, and sequencing of VFR aircraft to the primary airport.

Class B service provides approved separation of aircraft based on IFR, VFR, and/or weight, and sequencing of VFR arrivals to the primary airport(s).

What does approved mean?

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    $\begingroup$ What does the question in the first sentence have to do with the one in the last sentence? As noted in your comment on the accepted answer, you got and accepted an answer to one thing, but not the other. That's why 2 different questions in one post aren't allowed. $\endgroup$
    – FreeMan
    Jan 14 at 17:40
  • $\begingroup$ This is messy…. The original question was clearly and primarily about any differences between service in C vs B airspace. Clarifying the term “approved” was an ancillary aid to a more complete understanding. Seems we’ve dragged out a horse 6 years dead now for no good reason to define a term that was just a small part of the intent of the original question. True, the OP shouldn’t have accepted the partial answer… $\endgroup$ Jan 14 at 19:40
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The term is not "approved", it is the complete phrase Approved Separation. This is the standard FAA term for what was previously called either standard separation or radar separation, and means "separation in accordance with the applicable minima in [FAA Order 7110]".

The separation minima are further defined in the JO 7110 family of FAA Air Traffic Control orders, which you can find linked from the page above.

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  • $\begingroup$ What is the main difference between C and B then? $\endgroup$
    – pmoubed
    Oct 31 '15 at 14:59
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To answer both your questions in the context of :

First, "approved" in those sentences refers to the type of separation provided: "approved separation." This means separation that has been prescribed as being the best tradeoff between safety and efficiency, according to the bureaucrats who create the FAA's separation standards. (Separation standards are not prescribed in US Law [USC] or Agency-generated Regulations [CFR], but only in internal FAA Orders.)

This separation does not have to be a set distance. Planes may be separated by distance laterally and vertically, but they may also be separated by time and by other procedural practices (such as one-in-one-out at non-towered airports). If separation is prescribed in the 7110.65, it is "approved separation."

Separation between two IFR aircraft does not change based on airspace classification (though it can change based on the aircraft's altitude, and based on the type of radar system used by air traffic control).

"Approved separation" between two IFR aircraft is any of the following:

  1. Three nautical miles laterally (or in certain cases five miles; sometimes more, depending on wake turbulence).
  2. 1000' vertically (or in certain cases 2000').
  3. Pilot- or Tower-applied visual separation (not applicable in Class A).

These separation standards are the same in both Class B and Class C airspace.


The difference in separation standards in different airspace classes is related to VFR aircraft.

Class C Airspace, IFR-VFR

  1. Target resolution (the dots on the radar screen don't touch).
  2. 500' vertically.
  3. Pilot- or Tower-applied visual separation.

Class C Airspace, VFR-VFR
Traffic calls and safety alerts are provided, but there is no minimum separation.

Class B Airspace, VFR and "large" aircraft

  1. One-and-a-half nautical miles laterally (sometimes more, depending on wake turbulence).
  2. 500' vertically.
  3. Pilot- or Tower-applied visual separation.

Class B Airspace, VFR and "small" aircraft

  1. Target resolution.
  2. 500' vertically.
  3. Pilot- or Tower-applied visual separation.

I use "large" and "small" in quotation marks because they do not have their standard meanings (small: MTOW 12,500lb or less; small-plus: MTOW between 12,501lb and 41,000lb; large: MTOW between 40,001lb and 300,000lb; super: MTOW 300,001lb or greater). Instead, they are defined as:

  • "Large:" Any aircraft, helicopter, or rotorcraft, whether VFR or IFR, which either weighs more than 19,000lb or is a turbojet.
  • "Small:" Any aircraft weighing 19,000lb or less.

In Class D airspace no separation is provided between IFR-VFR nor VFR-VFR traffic, but traffic advisories and safety alerts are provided. In Class E airspace it is the same but, because VFR aircraft do not need permission to enter Class E, these advisories may not be fully complete.

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"Approved separation" means any separation specified in FAA Order JO 7110.65, Air Traffic Control, that has a minima (a numerical value) attached to it. Like "6,000 feet and airborne" or "1,000 feet" for vertical separation, or "3 miles" for radar lateral separation.

What about visual separation, you ask? Well, visual separation is a procedure by which separation may be reduced to anything below applicable published minima.

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