CMF Call Sign FAQs

The COMPASSION call sign and it’s three-letter designator CMF is intended to clearly identify routine ambulatory patient transport and other public service missions conducted by volunteers.The COMPASSION call sign was assigned to the Air Care Alliance as an organization that promotes public benefit flying in 1999.

Pilots should be active members of authorized VPOs and should be eligible to serve as PIC on
flights coordinated by their organization.

Additionally, in order to use any call sign that is not the aircraft registration number, the pilot’s
aircraft must be equipped with an ADS-B Out unit that is programmable by the pilot.

Most 1090ES ADS-B Out transponders and some 978 UAT ADS-B transceivers allow pilots to
edit the call sign. Sometimes that capability must be enabled or unlocked by an avionics shop. If
the ADS-B out unit is not programmable by the pilot, he/she will not be able to use a call sign.

If your aircraft is not equipped with a pilot-programmable ADS-B out unit, unfortunately, you will not be able to use a call sign other than your aircraft's registration (tail) number.

Most ADS-B transponders can be programmed. But many have a default setting that does not enable the programming function to work. In that case the unit can have the default changed by any avionics shop to permit the pilot to program the unit with the assigned CMF call sign.

Changing the setting is a fairly easy process and in most cases the unit can even remain in the plane.

This article from AOPA lists some of the more common ADS-B units and how to change the flight ID.

Pilots should consult their manuals or inquire with their avionics shop about their specific transponders.

The COMPASSION call sign is intended to clearly identify routine ambulatory patient transport and other public service missions conducted by volunteers including: animal transport, environmental flights, disaster response and other non-profit flying that serves the public interest.

Using the COMPASSION call sign has many benefits for the pilot, the organizations they fly for, as well as ATC.

● Allows pilots to clearly identify to ATC as a bona fide public benefit flight
● Gives pilots access to special handling by ATC (better routing, altitude changes, etc.)
● Provides a measure of safety and security for passengers who may have special
needs due to medical reasons.
● Encourages pilots to file a flight plan or use flight following on charitable flights which
allows for better tracking and more efficient mission coordination.
● Can provide authorization for flight operations during disaster response flights.
● Increases the value and awareness of public benefit flying within the aviation
community!

Pilots may register for their COMPASSION call sign by completing a simple form at this link:
https://www.aircarealliance.org/register/pilot-membership/

Once a pilot’s member status with their VPO(s) is validated, a call sign will be issued by email.

No. Pilots will only be assigned one COMPASSION call sign which can be used with any ACA Authorized group.

The current list of authorized groups is:

Aerobridge
Angel Flight East
Angel Flight Soars
The California DART Network (CalDART)
EVAC
Flight for Life
LifeLine Pilots
Pilots for Patients
Pilots for Christ – WY
Pilots N Paws
Turtles Fly Too
Vital Flight
VPG Air
Operation AirDrop

You may use your call sign on flights for any of these groups.

ACA welcomes any legitimate non-profit volunteer pilot group to become authorized to use the COMPASSION call sign. Groups can become authorized with ACA at any time. We expect this list to grow as more groups become authorized.

Your membership with the organization(s) you listed needs to be verified before a call sign can be issued. Verification time will vary depending on the group you fly for. It may happen automatically for some organizations, but could take several business days for others. Once your membership is validated, you should receive an email containing your assigned CMF number and instructions for use.

Procedures for use of the COMPASSION call sign may be found here. Please read and follow these instructions carefully.

COMPASSION and its associated three-letter identifier CMF are to be used to identify aircraft conducting bona fide nonprofit public benefit flying missions. This may include:

  • transporting individuals for health care, diagnostics, or treatment;
  • transporting blood, tissues, organs, or medical supplies;
  • transporting emergency personnel, equipment, and supplies in time of emergency or public need;

  • performing habitat or environmental survey or other missions in support of environmental objectives;
  • transporting rescue animals or wild animals needing relocation;

  • and in general conducting non-profit flying operations serving the public interest, especially those conducted by volunteers.

    COMPASSION must not be used for routine personal, business, or commercial flights. COMPASSION must not be used for positioning or ferry flights when during the times of flight an actual public benefit flying mission is not being conducted; EXCEPT that it may be used when there is a demonstrable need for appropriate (but not priority) handling by ATC.

  • Whatever Flight ID (call sign) is used in your flight plan must exactly match what's transmitted by the ADS-B.

    For example: If you put CMF2000 as the Flight ID on the flight plan, CMF2000 must be transmitted by the ADS-B. Alternatively, N1234 on the flight plan means N1234 transmitted by the ADS-B.

    ACA recommends adding “ensure proper flight ID” to your before takeoff checklist.

    No. Per FAA requirements, the Air Care Alliance’s three-letter ICAO designator CMF must not be used for call signs by third party flights outside of airspace controlled by the United States except for certain CMF flights that operate in other countries that have a use agreement with the Air Care Alliance and/or the FAA.

    No. Per FAA requirements, Air Care Alliance’s three-letter ICAO designator CMF must not be used for flights within the United States of third party foreign registered aircraft.

    The Air Care Alliance is the administrator of the COMPASSION call sign and grants its use to
    authorized Volunteer Pilot Organizations (VPOs) through third party agreements.

    In order to become an authorized user of the COMPASSION call sign, a VPO must:

  • Meet and attest to the ACA eligibility requirements.
  • Sign an FAA third party agreement authorizing use of the call sign.

  • Appoint a person to approve pilots who are members of their VPO*. The appointed person will receive an automated email containing a verification link whenever one of their pilots registers for a call sign. Call signs are not issued until a pilot is verified.

    *If the VPO uses VPOIDS as its flight coordination system, pilot verification will happen automatically and no point person is required.

    If your organization would like to become authorized to use the COMPASSION call sign contact Kristinia Luke at k.luke@aircarealliance.org

  • Your membership with the organization you listed needs to be verified before a call sign can be issued. This may happen automatically, or make take several business days depending on the group you fly for. Once your membership is validated, you should receive an email containing your assigned CMF number and instructions for use.

    If you still have not received your call sign after about a week, contact your group and ask them to verify you.

    If your group has verified your membership and you still haven’t received a call sign, please contact us at info@aircarealliance.org.