A Guide for Using Your CMF Call Sign

You’ve received your new CMF call sign and are ready to fly your first volunteer flight using it. Great! The COMPASSION call sign has many benefits. It alerts ATC that you are on an important charitable mission and provides a measure of safety and comfort for your passengers. Controllers may be more likely to clear you direct, give you better routing, or grant you an altitude change. But before you key up “COMPASSION” it’s important to make sure you are using the call sign correctly and in accordance with FAA instructions. This guide is designed to help you do that.

Make sure you’ve read and understand the procedures for use.

Procedures for use are emailed to you when your call sign is issued. They can also be found on the Air Care Alliance website at this link: https://www.aircarealliance.org/cmfprocedures/. Don’t skip this step. You must read and become familiar with the procedures for use.

IMPORTANT: Please be sure you are using the proper prefix. The proper prefix for the COMPASSION call sign is CMF–Charlie Mike Foxtrot. We’ve received reports of pilots improperly entering “CMP” rather than “CMF” in their flight plans. This is incorrect and is causing issues with ATC and FAA since “CMP” is the prefix for Copa airlines.

Ensure you are using the call sign with the right organizations.

It’s tempting to use your discrete call sign with every volunteer pilot group you fly for; however, please be aware you are only permitted to use the call sign with groups which are authorized for its use and which have approved you to use it. If you fly for more than one group, you can find the groups that authorized you by logging into your ACA account following the instructions at the end of this article. If an authorized group you fly for has not yet approved you, you should contact them to find out why and request verification.

NOTE: Any qualified legitimate volunteer pilot organization can become an authorized user of the call sign at any time, at no cost to them. If a group you fly for is not yet authorized to use CMF, but you’d like to use it, you should encourage them to become authorized.

File your flight plan.

Instructions for how to do this are included in the written Procedures at this link: https://www.aircarealliance.org/cmfprocedures/.

Configure your Flight ID*.

In order to use a call sign in designated airspace, you’ll need to make sure your ADS-B out unit is transmitting the Flight ID exactly as listed in your flight plan. It’s a good idea to add this item to your before take-off checklist. Remember, the COMPASSION call sign may only be used on flight legs that are part of the designated mission. Any deadhead legs should be flown using the aircraft’s N number, and the pilot must remember to reset the Flight ID to the aircraft’s N number when the mission is completed.

*For additional information on how to configure an ADS-B out transmitter, read: Call Sign Mismatch and Changing Flight ID

Enjoy the flight!

Using the COMPASSION call sign will make your public benefit flights smoother for you, your passengers, and Air Traffic Control and is an important part of volunteer flying. And using your skills to serve the needs of humanity is an admirable pursuit. Thank you for your service to those in need. We salute you!

IMPORTANT: It is your responsibility to keep the information in your account up-to-date. This includes contact information and any groups you are authorized to fly for. You can log in to your account at any time to do so.


  • On the Air Care Alliance website, go to “Log In” in the upper right corner (or click this link: https://www.aircarealliance.org/wp-login.php)
  • Enter your Username and Password.
    • Your username was emailed to you upon registration for the use of a CMF call sign. If you’ve forgotten your password you can reset it with the “Lost your password?” link. Need help? Email info@aircarealliance.org
  • Once logged in, click “My Profile” in the upper right hand corner.
    • At the bottom of the page is a block that lists your Call Sign ID and the orgs that have verified you to use it.
    • If you fly for additional authorized organizations not listed here, please ask them to verify you or contact info@aircarealliance.org for help.