ADMISSIONS: 661-615-5915 | MAIN LINE: 661-615-5915

Everything You Need to Know About the Mode C Veil 

The transponders that you find on aircraft can have a few variances based on who manufactured them and how they are installed. However, they should all have a few basic settings that are standard – and necessary.   

One such setting is a special mode that will let air traffic control and other aircraft in the sky know your 4-digit squawk code as well as your altitude. This is known as Mode C.  

What is the Mode C Veil and how is it used? Here is everything you need to know.  


What is the Mode C Veil?  

As previously mentioned, mode C is a setting on the transponder that must be used while operating an aircraft that is flying within the Mode C Veil – a type of airspace surrounding Class B airports within the United States, as well as a few other areas that you will want to get to know well.  

There are very few exceptions to this requirement due to safety concerns since the purpose of the Mode C Veil is to help those in air traffic control and those in the air around you maintain visibility at all times.  

The FAA is sure to see that you comply.  


Mode C Transponder and Airspace 

The Mode C Veil is a section of airspace that requires pilots to have a mode c transponder in order to give air traffic control the altitude and the 4-digit identification code. In order to travel within this airspace, you absolutely must have the proper equipment, unless you are one of the exceptions – a glider, a balloon, or an aircraft without a certified engine-driven electrical system. 

How do you find the Mode C Veil? How do you know you are traveling within in? As you move into the airspace around a class B primary airport you will be able to see markings on the VFR chart. Look for the magenta-colored ring that is 30 nautical miles from the airport. This ring will state “MODE C” so that it cannot be missed.    

There are additional spaces that will require mode C, as well. These include Classes A, B, and C, as well as 10,000 feet above mean sea level, and, again, within 30 nautical miles of a Class B  airport since they are some of the busiest within the county.  

As you enter the Mode C Veil,  you will want to ensure that your transponder is turned to the proper mode.  


Requirements for Mode C Transponders 

Not all transponders will be able to meet the mode C requirements. For instance, mode A transponders are those that provide the 4-digit identification code, but they do not provide any information about altitude – which is crucial. 

Another popular option, the mode S transponder, will most definitely fit the requirements set forth by the FAA and mode C airspace. This transponder is able to provide the proper data, including the 4-digit identification code and altitude information. It is also able to communicate with other aircraft.  

It is important to know that if the aircraft you are traveling in has a mode A transponder, it will not meet mode C requirements. However, if your aircraft has a mode S transponder, you should be just fine to make your way into the Mode C Veil airspace.  


Is a Mode C Transponder the Same As ADS-B? 

The ADS-B transponder works well to relay pertinent information, such as identification, position, altitude, and velocity to air traffic control as needed. This is quite similar to the mode C transponder. Just because they relay the same message does not mean they do so in the same way.  

Mode c transponders rely on radar whereas ADS-B transponders rely on satellite. While one can work in place of the other, as of January 2, 2020, the FAA made it a requirement that aircraft have an ADS-B transponder installed in addition to Mode C. 

Beginning on this date all aircraft are required to have an ADS-B transponder to enter Mode C Veils.  


Risks of Not Having the Proper Transponder 

There is certain airspace available in which not having a transponder will not be too much of an issue. For instance, if you are flying in Class D, E, and G airspace, you should be just fine. Those in rural communities who fly in their immediate area or those who have built their own experimental aircraft do not have to, either.  

If your aircraft and your travel plans do not fall into any of the above situations, then you are going to need to ensure your aircraft is equipped with the proper ADS-B transponder so that you can comply with the requirements.  

What happens if you violate?  

As of 2018, the FAA has brought forth an initiative that will help to correct those instances when someone does not comply with the requirements – unintentionally. Known as the Compliance Program, the FAA will find those that are not complying and take steps to correct the problem swiftly and effectively. They are allowing for honest mistakes rather than penalizing pilots.  

If you knowingly violate this requirement and fly into Mode C Veil without having the proper transponder, do not expect any leniency from the FAA.  

In order for the Mode C Veil to work and keep everyone safe, compliance is so important. Know the transponder you have before you take flight and, if you are not compliant, then avoid the veil. It is that simple. 


Learn About Mode C Veil – And So Much More at CAU 

The world of aviation is full of so many fascinating things to learn – even if it is only about Mode C Veil and various transponders.  

As you begin to train and gain knowledge from the aviation courses at California Aeronautical University, you will begin to see how all of the small pieces like this come together to help you become a successful pilot.  

Ready to get started? Request information today to learn more about what your future holds at CAU. We have programs for those looking to become pilots, as well as the many other roles within the industry.  

Ready to soar in your aviation career?

Schedule a Meeting Here
Skip to content