CMF Call Sign FAQs

FAQ (Frequently Asked Questions)

What is the COMPASSION Call Sign?

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.

What kind of flights can COMPASSION be used on?

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.

Can the COMPASSION call sign be used outside the United States?

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.

Can foreign registered aircraft use the COMPASSION call sign?

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.

What’s Changing?

Over the years, ACA has permitted VPOs use of the call sign through a specific filing process whereby a pilot enters the three-letter designator CMF on their flight plan, followed by the last three characters of their tail number. That procedure will no longer by authorized after December 15th, 2019. Pilots wishing to continue use of COMPASSION must be members of ACA authorized groups and they must register for a new, unique call sign through ACA.

Why the Change?

The change to the COMPASSION call sign process has to do with ADS-B implementation and FAA changes to call sign usage requirements.

Beginning January 1, 2020, ADS-B Out transponders will be required for all aircraft in airspace where transponders are mandatory today. This creates additional considerations for call sign usage.

The FAA issued an advisory circular containing updates to requirements and procedures for the use of aircraft call signs in the national airspace system.  The previous method of filing CMF did not meet these criteria. Therefore, new and unique call signs that meet FAA and ICAO requirements will be assigned by ACA to qualifying pilots who request one.

What is ACA's Role?

As the administrator of the COMPASSION call sign, the Air Care Alliance has worked with the FAA on behalf of public benefit flying organizations and volunteer pilots to develop new unique COMPASSION call signs which will be compatible with ADS-B out and FAA call sign usage requirements. ACA will assign these call signs, on request, to each qualified participating pilot for use on public benefit flights.

 

Can I Use the CMF call sign COMPASSION?

YES, if your public benefit flying group has been authorized to use the new call signs and you have requested and been assigned a new one.  The old filing procedure for using the COMPASSION call sign must not be used after December 15, 2019.  You may request your new call sign online IF you fly for a group authorized to use it and if you follow all the guidelines for use.

 

How does a volunteer pilot group become an authorized user?

The process is simple! In order to become an authorized user of the call sign, a group needs to sign two forms: 

The Air Care Alliance Affirmation (found on page 1 of the Membership Form). A group does NOT need to be a member of ACA to be an authorized user, but does need to agree to the affirmation.

FAA Security Agreement – The FAA requires that the ACA must obtain a security agreement before allowing third-party use of their call sign. Note: The security agreement requires that authorized groups maintain 24/7 points of contact on their website; however, please note that in the event the FAA requires information, they will contact ACA first and generally during business hours. Only in the rare event of an emergency will groups be contacted.

 

How do pilots register for a call sign?

Pilots who are members of an authorized group may register for their individual COMPASSION call sign by completing a simple form here. Once your member status is validated, you will be issued your call sign by email. This may happen automatically or may take several business days depending on the group you belong to.

 

Who should register for a call sign?

Active pilots of ACA authorized groups who are eligible to serve as PIC should register for a call sign. Please do not register for a call sign if you are a Mission Assistant (co-pilot) or otherwise not qualified to act as PIC for your organization. 

Additionally, unless you fly completely outside ADS-B required airspace, your aircraft should 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.

Note that volunteer pilots for qualifying organizations only need an ADS-B out transponder in order to fly in the mandated airspace defined by FAA – basically above 18,000’ MSL and in Class B and C related airspaces where a transponder is already required, including the airspace above, as well as the “Mode C veil.”
 
Pilots flying completely outside ADS-B required airspace can use their new COMPASSION call signs by including it in their flight plans following the procedures we have provided on our site or by using it when requesting flight following or making radio announcements.
 

Will the COMPASSION call sign work with an ADSB-Out transponder?

Yes or no, depending on your ADS-B out transponder.  You must have a model that provides for modifying and inputting a call sign appropriate for your mission since ADS-B broadcasts a call sign as programmed in an aircraft.  Many models can do this now, but this ability must be enabled at an avionics shop either during installation or later.  The call sign you program into the unit must exactly match the call sign you enter on your ICAO flight plan, if you filed a plan.  The call sign MUST conform to the new ICAO International call sign requirements as detailed in the procedures.

 

Will pilots be assigned a different call sign for each organization they fly for?

No. Pilots will only be assigned one COMPASSION call sign which can be used with any ACA Authorized group. (A list of authorized groups can be found on the registration page).

The CMF call sign is available to any legitimate volunteer pilot nonprofit group meeting ACA’s requirements to be an ACA Listed or Member Group and signing the required FAA Security Agreement available from ACA. Groups can become authorized with ACA at any time. The list will grow as other organizations become authorized.

 

What if I fly for an Angel Flight organization that uses the Air Charity Network call sign NGF?

The CMF call sign is administered separately from the NGF or “Angel Flight” call sign. Pilots who fly for Angel Flight organizations that have been assigned a unique NGF call sign can continue using the assigned call sign for flights with the organization that assigned it. 

You may separately register for a CMF call sign for use on flights for any other authorized volunteer pilot organizations you may fly for.

IMPORTANT: The changes to FAA and ICAO call sign requirements are not specific to CMF. You will need to comply with FAA and ICAO requirements, including having a programmable ADS-B out, in order to use ANY call sign that is not the aircraft’s registration number. 

 

Why can’t I find the group I fly for in the selection list when I register for a call sign?

Volunteer pilot groups must be authorized by the ACA to permit their pilots use of the COMPASSION call sign. If the group you fly for is not listed, it means they are not yet an ACA authorized user. They may have decided not to use COMPASSION or have simply not yet completed the authorization process. Please contact your group for more information.

 

Why should I use the COMPASSION call sign?

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.
  • COMPASSION 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!

How soon can I expect my call sign to be issued after I register?

Your membership with the organization 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.  
 
If you still haven’t received a call sign after about a week, please inquire with your organization about verification. 
 

How do I use the COMPASSION call sign?

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

 

Why isn't ACA's call sign assignment process more inclusive of pilots who cannot change their ADS-B?

The changes to call sign usage are directly related to new call sign requirements put into place by FAA and ICAO. It’s important to note that the call sign requirements related to ADS-B were not proposed or imposed by ACA, but rather by the FAA, and the rules are not specific to the CMF call sign. They apply to anyone wishing to use any call sign different from the N-number (or other registration number) that is initially programmed in an ADS-B out transponder.
 
ACA strongly believes the CMF call sign provides many benefits to volunteer pilots and most importantly, their passengers. In an effort to ensure that COMPASSION could continue to be used by as many pilots as possible, we have worked hard to develop a process acceptable to the FAA that meets the new requirements for call sign usage. Any group or organization that currently has or will seek to use its own call sign will have to meet the same FAA mandated requirements.
 
While the new FAA requirements do add some steps in order to use the call sign with ADS-B, without this process use of the CMF call sign for public benefit flights in ADS-B required airspace would cease to exist. We have taken every measure to ensure that as many pilots as possible can use the call sign under the new rules.
 

I don't think my ADS-B can be programmed. Does that mean I can't use the call sign?

Actually, there are relatively few ADS-B out transponders that cannot be programmed, and they tend to be early ones. 
 
A great many pilots do not realize that this is possible for their transponders. 
 
Most ADS-B transponders, except for some early ones, can be programmed. But many of those had a default setting that did 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.
 
ACA encourages pilots to inquire with their avionics shop about their specific transponders.
 
Note that volunteer pilots for qualifying organizations only need an ADS-B out transponder in order to fly in the mandated airspace defined by FAA – basically above 18,000’ MSL and in Class B and C related airspaces where a transponder is already required, including the airspace above, as well as the “Mode C veil.”
 
Pilots flying completely outside ADS-B required airspace can use their new COMPASSION call signs by including it in their flight plans following the procedures we have provided on our site or by using it when requesting flight following or making radio announcements.
 

Do I need to change the Flight ID field every time I fly?

Your assigned CMF call sign should only be used when conducting a bona fide public benefit flight. It should not be used on positioning or ferry flights, except in the rare situation where reaching a pickup or departure location is time critical and you may need ATC assistance, given on a workload permitting basis. Therefore if using a ADS-B transponder you should change the flight ID to match your call sign before a public benefit flight and change it back to your tail number after the public benefit flight is complete.
 
ACA recommends adding “ensure proper flight ID” to your before takeoff and after landing checklists.
 
While this seems like additional work, updating the Flight ID is as simple as entering a squawk code on regular transponders. And with some ADS-B units, you may only have to program your unique call sign into the unit once and then you will be able to simply select the proper pre-entered flight ID before flight.
 

I requested and received a unique CMF call sign. Can I use this with any group?

You may only use your assigned call sign with any group that is authorized by ACA to use the call sign. The most up-to-date list of authorized groups can be found in the registration drop down on the ACA website. You may also inquire with your particular group or email ACA to find out if a group is authorized.
 
The CMF call sign is available to any legitimate volunteer pilot nonprofit group meeting ACA’s requirements to be an ACA Listed or Member Group and signing the required FAA Security Agreement available from ACA. Groups can become authorized with ACA at any time. The list will grow as other organizations become authorized.
 

How do I know which groups are authorized to use CMF?

The current list of authorized groups is:
 
Angel Flight East
Angel Flight Soars
EVAC
LifeLine Pilots
Pilots for Patients
Vital Flight
Pilots N Paws
Pilots for Christ – WY
Turtles Fly Too
Pilots to the Rescue
Aerobridge
 
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 CMF call sign. Groups can become authorized with ACA at any time. We expect this list to grow as more groups become authorized. 
 

If my group isn't authorized to use the CMF call sign, but I indicate I'm on a Compassion Flight in the remarks of my flight plan will I get the same special handling as using CMF?

Not necessarily. The remarks section of your flight plan is not immediately visible to most air traffic controllers. While some ATC facilities who still use “strips” may be able to see your remarks, most facilities no longer use strips and would need to click into your flight plan to view any remarks. Many air traffic controllers simply do not have the time nor inclination to do so and expecting them to places additional burden on ATC. Your flight may also transcend sectors. This means that while one ATC facility who uses strips may see your remark, the next one may not, so you should not expect uniform treatment or special handling if you use this method.
 
Additionally, it should be noted that if your group has not been authorized by FAA and ACA and you have not been assigned a CMF number, then you are not permitted to use the telephony “COMPASSION” when identifying yourself to ATC.
 
 

When can I start using my new call sign?

As soon as you receive it! As long as you are following the procedures for use, you may begin using your call sign right away. You do not need to wait until January 1st.
 
 
Remember: The old method of filing CMF using a portion of the aircraft’s tail number is no longer authorized as of December 15th.
 

I registered for a call sign but still haven't received it. What do I do?

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

Additional Information

ADS-B: Changing Flight ID – Why Would You, How Do You?

Assignment of Aircraft Call Signs and Associated Telephonies