FAQ (Frequently Asked Questions): 

Q. Can I use the COMPASSION (CMF) call sign?
A. For now, yes, if you follow all the guidelines  on this page.  Note that the procedures for using it are changing.  You must be flying patients or on another official public benefit flight or exercise conducted for a nonprofit public benefit flying group and the group must be a Member group of ACA or be listed on our referral system - see more detailed information in the Procedures section below. Carefully follow these procedures to avoid ATC confusion and delays!


Q. Will the COMPASSION call sign work with an ADSB-OUT transponder?
A. Yes or no, depending on your ADSB 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 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 use on your flight plan.

Public Benefit Flying:
sm Call Sign and
Three-Letter Designator CMF

Call Sign Contents: Click on item to go directly to it

1999 Letter to Public Benefit Flying Groups and Pilots

Procedures for Use of Call Sign "COMPASSION"

Magazine Article in FAA's "Callback"

  1999 Letter to Public Benefit Flying Groups and Pilots

May 29, 1999

TO: Public Benefit Flying Organizations and Pilots

RE: Call Sign COMPASSION and three-letter designator CMF

Dear Friends,

On the first of this month at the Air Care Alliance 1999 national conference in Kansas City I announced that at our request the FAA had assigned an ICAO International Call Sign to the Air Care Alliance for use by all pilots and groups flying public benefit flying missions. At that time I indicated that a notice detailing the specific procedures for using the call sign, after development and a review by FAA, would be distributed to the various groups for use by the volunteers who perform the missions.

The enclosed three-page document should provide all the information your group and its pilots will need in order to begin using the call sign and associated three-letter designator. If you have any comments or questions please feel free to contact me.

In this mailing I have also included a copy of the article about the call sign that was distributed to FAA personnel in the April 13 issue of its agency newsletter, the FAA Intercom. Please note that the FAA worked hard to implement the call sign and deserves tremendous thanks for the help and advice we enjoyed.

Please freely copy these materials to your pilots and operational personnel. Note that a current version of the procedures will also be maintained on the Air Care Alliance website at and we encourage you to provide a link to it from your own site.

We at the Air Care Alliance hope that this new tool will assist you in your and your volunteers' worthy work flying to help others.

With Warm Regards,

  Rol Murrow

Rol Murrow, Chairman Emeritus
The Air Care Alliance

ENC: COMPASSION Procedures for Use; Intercom article

  Document "Procedures for Use" for Call Sign COMPASSION
Effective May 30, 1999

Information updated September, 2019

NOTE:   These procedures involving use of portions of your own N-number may only continue to be used, possibly until DECEMBER 31, 2019 if you will not be using an ADS-B out transponder and will not be flying in the associated required airspace, but soon the procedures will not be able be used at all, including with an ADS-B out transponder, especially after January 1, 2020.  The format of the call signs below is incompatible with ADS-B out requirements.

The Air Care Alliance is working with FAA to develop new unique COMPASSION call signs that begin with the identifier CMF and which can be assigned to each qualified participating pilot and which will be compatible with ADS-B out equipped aircraft that are capable of being reprogrammed with a call sign for an appropriate public benefit flight. 

Stay tuned for instructions on how pilots flying for ACA member or listed groups can obtain unique CMF call signs for their aircraft.  Be sure you have subscribed to our bulletin and newsletter list by using the link at the bottom of this page.

Be aware that after January 1, 2020 the call sign used on the ICAO flight plan form and any call sign programmed into any ADSB-out transponder must be exactly the same as the call sign used in the filed flight plan.  Call signs using the procedures below will NOT be valid.

Public Benefit Flying Three-Letter Designator "CMF"
and Associated Radiotelephony Call Sign "COMPASSIONsm"

OLD FORMER Procedures for Use by Designated Pilots and Groups

NOT TO BE USED AFTER DECEMBER 31, 2019 or such date as may be announced by the Air Care Alliance.

Author: Rol Murrow, Chairman Emeritus, Air Care Alliance

Effective Date: May 30, 1999


This document discusses the Air Care Alliance's international aircraft call sign COMPASSION and its associated three-letter designator CMF, describes the procedures to be used to apply the call sign for a public benefit flying mission, and indicates when the call sign is appropriate for use.  Updates will be maintained at


Pilots flying public benefit missions and air traffic control (ATC) personnel have long recognized the need for a call sign that identifies such missions. Routine ambulatory patient transport and other public service missions conducted by volunteers usually do not warrant the priority handling provided through the use of the MEDEVAC (formerly LIFEGUARD) call sign, which is intended only for time critical medical and emergency operations such as those involving air ambulances.

The call sign COMPASSION has been developed to meet that need. Upon a formal request the call sign was assigned for administration to the Air Care Alliance as an organization that promotes missions conducted by pilots flying for all public benefit flying organizations or to similarly serve the community and public agencies.

The authority for call sign assignment and usage may be found in the US DOT Federal Aviation Administration (FAA) Advisory Circular 120-26H, especially under the criterion "… when deemed advantageous for air traffic control and operational purposes."


COMPASSION and the Three-Letter Identifier CMF have been assigned as an International Civil Aviation Organization (ICAO) Radiotelephony Designator and Three-Letter Identifier and are thus suitable for both domestic and international operations.


COMPASSION and its associated three-letter identifier CMF are to be used to identify aircraft conducting bona fide nonprofit public benefit flying missions as from time to time may be defined in this document or revisions to it. Such missions may include the following: 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; and in general conducting non-profit flying operations serving the public interest, especially those conducted by volunteers.

COMPASSION may be used during a positioning or ferry leg of flight when patients, supplies, or emergency personnel are not being transported only if such a flight leg has time constraints and there might be a need for helpful (but not priority) handling by ATC.


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. Such need might be to complete in a timely fashion a subsequent public benefit flight mission. COMPASSION must not be used for flights other than those defined in this document unless permission is obtained beforehand from the Air Care Alliance or the Federal Aviation Administration. See AC 120-26H paragraph 11.a.

Instructions for Use on Flight Plans:

These instructions are demonstrated in the examples below. Pilots must file a flight plan using all normal procedures, with the following two differences:

1) In the block used for the aircraft registration (tail) number the pilot shall enter the ICAO Three-Letter Identifier CMF followed by three or four additional characters or numbers, consisting of the final three or four characters of the actual tail number of the aircraft to be used. (The block can hold a maximum of seven characters).

Normally pilots would use the last three characters of the tail number, unless it is known that another aircraft using the same number might be flying in the same area, in which case the last four characters would be used in order to avoid confusion.

Example:        Actual Aircraft Tail number:           N7371G

    Aircraft Registration Block Entry: CMF71G    ( or: CMF371G )

        (DO NOT USE the incorrect overlong entry: CMF7371G)

2) In the REMARKS block the pilot should enter, separated by spaces, first the word COMPASSION followed by the full registration (tail) number of the aircraft, followed by the name of the public benefit flying organization (if any), and then any other remarks.

Example:     REMARKS:    COMPASSION N7371G VOLUNTEER FLIERS …[Followed by any other remarks]

Radio Usage:

Normally pilots will identify themselves to ATC on initial call-up using the word COMPASSION and the chosen three or four letters from their tail number as shown in the flight plan:


"City Approach, COMPASSION Seven One Golf level at three thousand feet."


Pilots and volunteer pilot organizations are strongly cautioned NOT to use the call sign MEDEVAC (or LIFEGUARD) except for situations as defined in the Airmen's Information Manual (see AIM 424 a or b), military AIR EVAC manuals, air traffic control handbooks, and/or other official documents. Using or requesting MEDEVAC (or LIFEGUARD or the L prefix) is considered to be a de facto request for priority handling, which could cause diversion of other aircraft and possibly great disruption of operations conducted by other users. It is intended to be of use when expeditious flight handling is required.

The new call sign COMPASSION is now available to identify the nature of public benefit flying missions and would normally be used for most volunteer-flown service missions.

However, should a transported person's medical condition deteriorate in flight or other conditions apply that justify expeditious handling on a priority basis, then MEDEVAC should be considered as likely more appropriate for use. ATC personnel can assist a pilot in making that decision, but pilots are advised to familiarize themselves with call sign usage and not to hesitate to use MEDEVAC if safety or medical necessity warrant its use, including changing a flight to MEDEVAC during flight if appropriate.

COMPASSION likewise has been designated to serve the public convenience, good, and necessity and we strongly encourage pilots to adopt its use for public benefit flying missions. However, some ATC personnel may be unfamiliar with the new call sign, so do be prepared to use traditional filing methods and do not be argumentative.

Also note that should pilots or organizations abuse the use of the call sign then the Air Care Alliance or the FAA can withdraw permission for its use or institute additional restrictions on its use. Likewise, should the Air Care Alliance fail to specify and authorize use of the call sign in a safe, fair, and non-discriminatory fashion then FAA may choose to revoke the authority for the use of the call sign by the Air Care Alliance and its designees.


FAA published an informative article about the COMPASSION call sign in its magazine for FAA personnel, "Callback."


The following article was published in the April 13, 1999 FAA Intercom newsletter April and circulated to personnel at all FAA Regional Offices.

FAA Intercom

April 13, 1999

Calling All Angels

Picture: Angel Flight West is part of the Air Care Alliance that provides medical and relief-related air transport services.

It is now easier to identify angels in the air, thanks to the FAA. The agency has assigned a three-letter identifier code that can be used by pilots across the country flying as part of the Air Care Alliance, a group of non-profit charitable organizations that provide medical transport for patients.

The organization’s 4,000 members — including many FAA employees — also provide transport for tissue/organ transplants and emergency/disaster relief efforts.

The new three letter identifier — CMF — and its radiotelephony call sign, "COMPASSION," make it easier for pilots to file flight plans with the FAA, reduce potential confusion about their mission, and provide a heads-up to air traffic controllers about the type of flight they will be handling.

Rol Murrow, former chairman of Air Care Alliance, explained that some Air Care Alliance flights in the past have been mistakenly identified as "Lifeguard" flights, which receive priority handling by air traffic controllers because they involve life-and-death situations. Although some Alliance flights are flown under the "Lifeguard" identification, it is usually not necessary.

Using the CMF identifier, however, does allow Air Care Alliance pilots to request

special handling to keep patients comfortable, such as flying at lower altitudes or on routes that avoid potential turbulence.

Angel Cases, an airspace and procedures specialist in the New England Region’s Air Traffic Division, was one of the FAA leads in designating the new identifier code. Because of their mission to communities throughout the U.S., Cases expedited Air Care Alliance’s request for an identifier code. "I needed to make sure they met the requirements, and if they weren’t able to, I wanted to assist them in documenting a case for a waiver to the requirements. That way they would be able to perform their mission," Cases said.

Because of the FAA’s work on this issue, volunteer pilot organizations like Angel Flight Northeast in Andover, Mass., Wings of Mercy in Muskegan, Mich., and Angel Flight West out of Santa Monica, Calif., can now provide their missions of mercy in a clearer, safer environment.

In addition to Cases, Murrow wanted to especially thank John Elliott in the Air Traffic Operations Program and all the other FAA offices that helped with this effort. "Air Care Alliance’s mission has been supported steadfastly by officials and the rank and file of the FAA," Murrow said.

Information provided by the Air Care Alliance - if you copy this information please do so in its entirety including this notice. Use your browser's BACK button to return to prior page.


FAQ (Frequently Asked Questions): 

  1993 MEMORANDUM to ACA Member Groups and Affiliates
and to all others involved in public benefit flying

Dear Friends,

Periodically we receive inquiries from pilots who are concerned about a rumor they heard that FAA might have a problem with pilots taking a tax deduction for flying bona fide public benefit missions. In the early 1990’s some at FAA did circulate such information for a short time, but it was quickly rescinded and now the rumor still keeps coming up, even though it is not true. This letter is intended to provide the latest information on the tax deduction issue so that you can answer questions authoritatively. Please notify us if you have questions or hear anything different.

After the Air Care Alliance requested a clarified policy statement FAA reviewed the matter and released guidelines which certainly seem to remove the concerns about the legality of taking a tax deduction for bona fide public benefit flying.

I will reproduce here some of the previous messages that have been circulated among the Air Care Alliance and related groups concerning this issue. See for yourself, but FAA and IRS both seem to be clearly saying that taking a tax deduction for flying a mission for a true nonprofit flying group is perfectly fine, as long as the flight and the deduction follow the proper guidelines.

I am not an attorney and thus cannot provide you with legal advice. Please read the following sections carefully and if you are still concerned then ask your group's legal counsel to review them and advise you and your pilots. If you hear anything different from local FAA officials then please have your public benefit flying group take these documents to your local FSDO and ask their opinion about your work and policies. I do NOT suggest that individual pilots burden the FSDO with numerous individual queries - please work through your group. If your group’s attorney or you find that there are documents or opinions that seem to contradict these messages, please notify us immediately so we can continue to act before FAA on behalf of all the groups.

Thanks, and I certainly hope you and your volunteers are continuing to enjoy the satisfaction of serving our communities through flying to help others!

Sincerely yours,

Rol Murrow

FAA Information Circulated to ACA and Affiliated Groups - 1993

FROM:     Air Care Alliance

RE:         TAX DEDUCTION ISSUE: Welcome News!

As discussed at the AIR CARE 93 conference, there has been concern about individuals taking a tax deduction for costs incurred in flying a public benefit flying mission. John Haverland of Angel Flight of Texas and we asked for clarification. The offices of FAA's Tony Broderick, Associate Administrator for Regulations and Certification, and John Cassady, Acting Chief Counsel, collaborated and came up with a policy statement reflecting Chief Counsel's position regarding this issue. Here is the policy statement to help guide you and your members:

Apr 23, 1993

"As a matter of policy, taking into consideration the fact that Congress has specifically provided for the tax deductibility of some costs of charitable acts, we will not treat charitable deduction of such costs, standing alone, as constituting "compensation or hire" for the purpose of enforcing [Paragraph] 61.118 or Part 135. If taking a charitable tax deduction for transporting persons or property is coupled with any reimbursement of expenses, or other compensation of any kind, then this policy does not apply."

[Signed] John H. Cassady FAA Acting Chief Counsel  

More Recent FAA Opinion Concerning Tax Deduction Issue - 1995

Background: In late 1994 and early 1995 a message circulated on the Internet stating that taking a tax deduction violated FAA regulations.  Some publications repeated the erroneous information.  Because the Cassady opinion statement had not been officially released, FAA took action to publish the issue formally. Rick Cremer, FAA's representative on Compuserve, presented the result there to settle the matter once and for all:

762019 S15/FAA Topics
23-Feb-95 11:17:31
Fm Rick Cremer FAA HQ 72130,3305


Recently, the FAA published Change 10 to it's Air Transportation Inspector's handbook (FAA Order 8400.10). That change included new guidance for our inspectors concerning Angel Flights. Included below, is the full text of guidance. What it says, basically, is that if a person takes a charitable tax deduction for the costs associated with the operation that does not constitute a for hire or compensation operation.

Best Regards

Rick Cremer FAA HDQ

FAA Order 8400.10, Vol. 4, Chap. 5, Sect. 1, Para 1345   12/20/94


FOR CHARITABLE FLIGHTS OR LIFE FLIGHTS. Various organizations and pilots are conducting flights that are characterized as "volunteer," "charity," or "humanitarian." These flights are referred to by numerous generic names, including "lifeline flights," "life flights," "mercy flights," and "angel flights." These types of flights will be referred to as "life flights" in this section.

A. Purposes for Life Flights. The types of organizations and pilots involved with or conducting life flights vary greatly. The most common purpose of life flights is to transport ill or injured persons who cannot financially afford commercial transport to appropriate medical treatment facilities, or to transport blood or human organs. Other "compassionate flights" include transporting a child to visit with a dying relative, or transporting a dying patient to return to the city of the patient's birth.

B. FAA Policy. The FAA's policy supports "truly humanitarian efforts" to provide life flights to needy persons (including "compassionate flights"). This also includes flights involving the transfer of blood and human organs. Since Congress has specifically provided for the tax deductibility of some costs of charitable acts, the FAA will not treat charitable deductions of such costs, standing alone, as constituting "compensation or hire" for the purpose of enforcement of FAR 61.118 or FAR Part 135. Inspectors should not treat the tax deductibility of costs as constituting "compensation or hire" when the flights are conducted for humanitarian purposes.    

The above information relates to the FAA.  What about the IRS?

    Internal Revenue Service Treatment of Public Benefit Flying - 1993

The following information was provided to the Air Care Alliance and affiliated public benefit flying groups in 1993.


I was requested by a pilot who flies public benefit missions to provide information about a specific Private Letter Ruling the IRS issued. It may provide some clarification regarding how the IRS regards taking a tax deduction for expenses incurred on behalf of a public benefit organization. I've copied the pertinent sections below and provided the reference for those who wish to look at the entire letter and its citations.

NOTE: CAUTION - DISCLAIMER - DON'T TREAD ON ME! This is an IRS LETTER RULING to a PARTICULAR UNNAMED GROUP. These letters are published to give people an idea of how the IRS has treated issues in the past, but you must heed the disclaimer paragraph near the end. Likewise, this relates only to certain provisions of the IRS code, regulations, or rulings. If you have further questions please feel free to contact me.

Rol Murrow, Chairman

From Page 1373 of The Exempt Organization Tax Review:

LTR 9243043

Aviation Program Expenses Are Deductible

The Service has ruled that volunteer pilots may deduct expenses directly related to a program that promotes public interest in aviation.

Date: July 29, 1992

Refer Reply to: CC:IT&A:3 TR-31-1130-92...

"Dear ...[unidentified Foundation],

"This responds to your letter of June 3, 1992, in which you request a ruling as to the tax treatment of expenses incurred by participants in a program sponsored by Foundation under section 170 of the Internal Revenue Code."  (Continued...)

[ED. NOTE: The opening of the letter describes the unnamed Foundation as a valid 501(c)(3) tax exempt organization and describes its charitable purpose, plus the program in which volunteers will provide introductory flights to youths] ...

"Volunteers will incur out-of-pocket expenses related to the demonstrations. These costs are: (1) fuel and oil for the actual flight; (2) transportation to and from the airport; (3) rental charges for a bus or van; (4) rental charges for an airplane used only for the program; (5) extra liability insurance incurred only for the program; (6) postage for mailing registration records; and (7) landing and tying down fees at a non-base home airport. Other expenses incurred by the volunteers for the youths are: (1) aeronautical educational materials; (2) meals; and (3) film and development.

"The volunteers will not be reimbursed by Foundation, or any other organization or person for demonstration and incidental costs."

[ED. NOTE: The next sections cite and review certain IRS Code Sections, Regulations, and Rulings relating to various of the above expenses. In one case, a vehicle owner driving for his church was not permitted deduction of the full fair rental value of his personal automobile and airplane because:... ]

"...the vehicles remained under the taxpayer's control at all times. A deduction for depreciation was also denied because depreciation is not considered a payment. The court further denied a deduction for insurance premiums and the cost of repairs because the church was not the sole beneficiary of the insurance, and the repairs were not shown to have been caused by the use of the vehicles for solely charitable purposes. The court, however, held that the taxpayer was entitled to a deduction for out-of-pocket expenses including unreimbursed expenses for gasoline, oil, and pilot and license registration fees.

"Volunteer pilots rendering gratuitous services to Foundation aid Foundation in carrying out its exempt purpose. Therefore, expenses actually incurred by volunteers in direct connection with, and solely attributable to the performance of such services are contributions to Foundation. Accordingly, we conclude that the expenses listed above are deductible under section 170 of the Code.

"This ruling is directed only to Foundation. Section 6110(j)(3) of the Code provides that this ruling may not be cited or used as precedent.

"No opinion is expressed as to the federal tax consequences of the transaction described above under any other provision of the Code than section 170.

"Sincerely yours,

"Assistant Chief Counsel, (Income Tax & Accounting)
by Michael D. Finley, Chief, Branch 3." 

February 13, 2007 Update:

FAA AIR TOUR RULES ANNOUNCED: Volunteer Pilot Public Benefit Flying Missions Untouched by New Regulations.  - February, 2007.

FAA makes changes in proposed rules as requested by the Air Care Alliance.

On February 13, 2007, the Federal Aviation Administration (FAA) published its final “National Air Tour Standards” regulations.   In response to comments and testimony given in Washington by the Chairman and the Regulations Committee Chairman of the Air Care Alliance, the FAA withdrew a proposed amendment to FAR §61.113 that would have created confusion and potential regulatory and insurance problems for volunteer pilots.

FAA’s explanation of the final rule, while in other sections still somewhat confused on various other types of charitable operations such as local fundraising sightseeing flights, emphatically restated its policy on volunteer patient transport flights and other community service missions:

"Additionally, nothing in the old rules and nothing in this new rule prohibits a private pilot from taking a sick or injured person from point to point as long as it is not for compensation or hire. By longstanding enforcement policy, the FAA has allowed aircraft operators who take a charitable tax deduction to transport a sick or injured person without that operator having an air carrier certificate. No other form of compensation may be received. "

We are very pleased with FAA’s continued support of charitable public benefit flying.

This information is provided by the Air Care Alliance - if you copy this information please do so in its entirety including this notice.  Use your browser's BACK button to return to previous page.