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Decoding the National Airspace System Nas of Classifying Air Traffic



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United States Aerospace System

Working at one of the busiest airports, at one of the busiest general aviation airport, I consider myself to be an extremely busy instructor. Airspace is a huge part of my daily teaching curriculum. I have to make sure that all my students stay save and do not go to areas they are not allowed to go. This article is a breakdown for everyone who flies in busy airspace or just wants to study up on it.

Airspace is easy. When I moved to California I took a look at a sectional (the chart used for navigating in a larger area), as well as, the Terminal (the chart used for a terminal area). I thought I'd forgotten how to fly! This was nothing than the "King's" upside down wedding cake, which I had grown so accustomed to in Minnesota. (Not much heavily controlled airspace out there).

This is a guide to all the minimum requirements for you as a private, or student pilot to enter some of the most used United States aerospace system. This will not include special airspace, for which, I'll write a separate article.

Class A or Alpha is not defined on the sectional. However, it goes from 18'000 ft up to 60'000 ft MSL (Above Mean Sea Level). Since Class A is high up there you will not go up there as a private pilot. Mainly because an IFR (Instrument Flight Rules) rating is required. Remember, that on top of being rated as an IFR pilot, you must also file an IFR flight plan. Naturally there are no weather minimums since you're IFR. Above 24'000 ft MSL you must also have DME (Distance Measuring Equipment) in your aircraft.

Class B or Bravo, think busy! This airspace is for the busiest of airports, such as, LAX, JFK, etc. It is clearly defined on the charts by a solid blue line. Class B will generally extend from the surface up to 10'000 ft MSL. It can look like an upside down wedding cake with different stages from the surface to 10'000 ft MSL. Don't count on that wedding cake though. Check out a terminal for the LA area and you'll see immediately what I mean.

Student pilots may enter Class B with an instructor endorsement that they've had the appropriate training to enter Class B. There are exceptions to private pilots being able to take off and land in certain Class B airspaces. For information on what airports are included in this refer to the FAR/AIM (Federal Aviation Regulations/ Aeronautical Information Manual), for a list. You can find the list under the AIM chapter 3 section 2-3 part 2.

Equipment requirements are as follows; you must have a two way radio. If you are under IFR operations you must have a VOR. Your aircraft must be equipped with a Mode C transponder with altitude encoding capability. You must know that there is a 30 NM (Nautical Mile) veil around the Class B in which you must have a transponder. On your checkride: This might become somewhat of a trick question. Your airport might be shadowed by airspace that does not require a transponder, but if it's under the veil you need it.
Visibility and cloud clearance requirements for VFR operations are simple. 3-COC or 3 SM (Statue Miles) and Clear of Clouds. Speed limits are 200 Knots in the VFR corridor and below the airspace. 250 kts within.

CLEARANCE! It is imperative that you hear the controlling agency (ATC air traffic control) say N1234 you are cleared through the Bravo airspace. If you don't, you simply do NOT enter, unless, you want to copy a phone number.

Class C or Charley airspace. It is clearly defined on the charts by a solid magenta line. Class C has two shelves. The inner shelve extends generally from the surface up to 4'000 ft MSL. The inner shelve has a radius of 5 NM. The second shelf generally starts at 2'000 ft MSL up to 4'000 ft MSL and has a radius of 10 NM.

This airspace is open to all pilots. Unlike class B you do not need to be cleared. You simply need to be acknowledged. So you'd simply need to hear: "N1234 stand by" and you may entered. If the controller said something along the lines of: "Cessna calling stand by", stay out.

The equipment requirements are simple. Two way radios and a mode C transponder with altitude encoding capability.

Visibility and cloud clearance requirements for VFR operations are 3-152. 3SM visibility, 1'000 ft above the clouds, 500 ft below the cloud and 2'000 ft horizontal. Easy to remember if you think of a Cessna 152. Once you've remembered this number bear in mind that it's the same for C, D and E. The speed limit is 250 within, 200 below 2'500 AGL or within 4SM of the airport.

Class D or Delta airspace. It is clearly defined on the chart by a dashed blue line. Class D is just a single cylinder. Generally has a 4 NM radius and goes from the surface up to 2'500 ft MSL.

Again, this airspace is available to all pilots. You do need to make contact with ATC and follow instructions as to how you have to enter the flow of traffic.

The equipment requirements are even easier than Charley's. Simply have two way radios.

Visibility and cloud clearance requirements for VFR operations are 3-152. The limits are: 250 kts within and 200 kts within 200 SM or below 2'500 AGL.

Class E or Echo. Is not quite as clearly defined as the other airspaces. The beginning of the airspace can either start at the surface, 700 ft AGL, or 1'200 ft AGL. The surface is depicted by a dashed magenta line, 700 ft AGL is faded out magenta (E airspace is only on the faded side of that line) and finally there's 1'200 ft AGL, which is indicated by a faded blue line (E airspace is only on the faded side of that line). E airspace extends up to, but not including 18'000 ft MSL (17'999 ft MSL). This airspace is most definitely controlled by the centers. You'll find their frequency on the charts and many other resources. However, these centers are mostly for IFR traffic. If you request VFR flight following to another airport or have a filled flight plan they'll be happy to work with you. If you're requesting flight following for the practice area they'll generally will not be too happy with you because they are too busy. This is especially true in terminal areas such as LA.

A large chunk of airspace is E and is open to all pilots. There are no special equipment requirements that you must have on board. A fun little fact (even though you will probably not get up there in the near future): after A airspace at 60'000 ft MSL it becomes E once again.

Just like before the visibility and cloud clearances are 3-152. However, there is an exception to this. At 10'000 ft MSL the speed limit of 250 kts in E is cancelled and there's no longer a limit to your speed. This mean that in VFR operations the FAR requires you to have 5-111 or 5 SM visibility, 1'000 ft above, 1'000 ft below and 1 mile horizontal.

Class G or Gulf is not defined on the charts. It is completely uncontrolled airspace. Nothing is required here and any pilot can fly in it. It fills everything that is not either A, B, C, D or E. Gulf extends from the surface up to 14'500 ft MSL.

The visibility requirements are all over the place, but as long as you remember the numbers you'll do well on your checkride.

Day Night
Below 1'200 AGL 1 - COC 3 - 152
Above 1'200 AGL 1 - 152 3 - 152
Above 10'000 AGL 5 - 111 5 111

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