The key to a lot of the information in an ACARS message is the message label. The two character message label represents a number of things about the message including the originator, and the type of information that can be expected in the message.

Many airlines use the same message labels but a number of airlines have defined their own labels, notably Air Canada, British Airways just to name a few.

On this page, we are listing examples of the contents that can be expected from the different message labels. This list is by no means complete, and we welcome additions so that we can make this a comprehensive reference page. If you have any additions, contact Tony

Here is an example of where a Mexicana A320 has been requested to change its ACARS frequency to 130.025 (Note the message does not display the data correctly in the right fields).

ACARS mode: 2 Aircraft reg: .F-OHMI
Message label: :; Block id: V Msg. no: 1300
Flight id: 25
-----------------------------------------------------------[08/11/1997 10:00]

On the surface, there appears to be no message label in the message?  Actually its a _<del> which appears as a "_  " which is  normal. Messages with this label are usually acknowledgements of uplinked messages that have been properly received by the aircraft.  In this sequence below, note the uplink to the aircraft, followed by the acknowledgement message that indicates reciept of the message, and has the "_ " message label.

ACARS mode: 2 Aircraft reg: ..B-HOS
Message label: C1 Block id: G Msg. no: .HKG
Flight id: YRCX 0
Message content:-
90800
AGM
AN B-HOS/GL LAX/MA 408A
- LOADSHEET EDNO 04
LAX HKG CX0881/08 B-HOS
F18J56W313 4/18/0 09NOV97

ZFW ACT 227720 MAX 244939
TO FUEL 16600
-----------------------------------------------------------[09/11/1997 00:00]
ACARS mode: 2 Aircraft reg: ..B-HOS
Message label: _ Block id: 0 Msg. no: S13A
Flight id: CX0881
-----------------------------------------------------------[09/11/1997 00:00]

Message label 10 when transmitted by American Airlines or American Eagle aircraft usually represents a change to the ACARS frequency being used (FQY30025 which equals changed to 130.025). Also included in these messages is the other supplementary information which is the destination airport, in this case (PIA) Peoria Illinois.

ACARS mode: 2 Aircraft reg: .N533AT
Message label: 10 Block id: 3 Msg. no: 5413
Flight id: MQ4059
Message content:-
OS PIA /FQY30025
-----------------------------------------------------------[04/01/1998 08:55]

Here is an ETA report transmitted by a British Airways 747 en route from Washington Dulles to London-Heathrow just after departure. It shows an estimated arrival time at London (IATA Code EGLL) for 0502(UTC).

ACARS mode: 2 Aircraft reg: .G-AWNP

Message label: 10 Block id: 0 Msg. no: 3056

Flight id: BA0216

Message content:-

ARR01 EGLL0502 00

 

------------------------------------------------------[14/09/1997 22:31]

 

Here is another version of the ETA message format, this type (FST) includes the flight route (Mexico D.F. MMMX) to (London-Gatwick EGKK), the current position of the flight (N376904W0794497), altitude (33007), wind direction and velocity (019/061), and estimated time of arrival (XA 1237 UTC):

 

ACARS mode: 2 Aircraft reg: .G-BNLD
Message label: 10 Block id: 3 Msg. no: 0902
Flight id: BA2242
Message content:-
FST01MMMXEGKKN376904W079449733007380380 019061 XA1237
-----------------------------------------------------------[09/11/1997 06:09]

Here is a Fedex format ATIS (Automated Terminal Information Service) weather request for destination airport Newark International (KEWR):

ACARS mode: 2 Aircraft reg: .N68050
Message label: 10 Block id: 0 Msg. no: M19A
Flight id: FX1021
Message content:-
301021/WXREQ /TYP 1/STA KEWR
-----------------------------------------------------------[30/12/1997 08:54]

 

Following successful transmission and reception of the TYP 1 weather report requested, the following message acknowledging receipt of the report is transmitted automatically by the airborne subsystem:

 

ACARS mode: 2 Aircraft reg: .N68050
Message label: 10 Block id: 2 Msg. no: M20A
Flight id: FX1021
Message content:-
301021/ACKMSG/5434
-----------------------------------------------------------[30/12/1997 08:54]

ACARS mode: 2 Aircraft reg: .N421FE

Message label: 11 Block id: 4 Msg. no: M28A

Flight id: FX1193

Message content:-

210601/INRANG/DS KIAD/ETA 0757/FOB 016080 UTM LB

----------------------[21/10/1997 07:39]

Here is a corporate aircraft (denoted by Flight ID GS0001) passing a flight plan as free text entry into the ACARS unit:

ACARS mode: 2 Aircraft reg: ..N96JA
Message label: 14 Block id: 5 Msg. no: M38A
Flight id: GS0001
Message content:-
(2AAAWN41583W 85170GDC N96JA GDC PLZ FILE
IFR FLT PLA N KTEB KMDW DEPARTUR E TIME 2045Z 3PAX 80 MACH FL390 18000FUEL ALT
KIND PIC ZUCCHER (Z
--------------------------------[04/01/1998 12:56]

 

Here is another example of a corporate aircraft free text message. Note that this example is a message from aircraft N336QS to another company aircraft N334QS:

 

ACARS mode: 2 Aircraft reg: .N336QS
Message label: 14 Block id: 7 Msg. no: M06A
Flight id: GS0001
Message content:-
(2ABAAN39238W076295334QS 336QS HEY BOYZ
WE GOIN TO GREENSBUROW THEN TO ROA OF COURSE THI S IS AFTER A 445 WAKE
CALL AND GOIN EWR-ALB-LGA-EWR WHAT ABOUT YOU (Z
-----------------------------------------------------------[18/12/1997 17:56]

Although not confirmed, this is believed to be the standard message label for corporate aircraft position reports.

ACARS mode: 2 Aircraft reg: .N918MK
Message label: 15 Block id: 5 Msg. no: M18A
Flight id: GS0001
Message content:-
(2N41449W 87420079 3 11 4(Z
----------------------------[04/01/1998 12:57]

 

Here is another example of what is believed to be a position report from Gulfstream 3 N317ML, including altitude (last three digits in first group of numbers after the longitude, in this case 37, 500 feet):

ACARS mode: 2 Aircraft reg: .N317ML
Message label: 15 Block id: 7 Msg. no: M06A
Flight id: GS0001
Message content:-
(2N37572W 75592281 34375-60(Z
-----------------------------------------------------------[02/01/1998 14:31]

Note that in this next message, the aircraft has climbed to an altitude of 38, 900 feet at the time of transmission:

ACARS mode: 2 Aircraft reg: .N317ML
Message label: 15 Block id: 8 Msg. no: M07A
Flight id: GS0001
Message content:-
(2N36163W 77013273 42389-59(Z
-----------------------------------------------------------[02/01/1998 14:46]

Although not confirmed, this is believed to be the standard message label for corporate aircraft weather requests. Below is an example of an Executive Jet Aviation Citation-V requesting weather for several cities in Michigan.

ACARS mode: 2 Aircraft reg: .N331QS
Message label: 16 Block id: 0 Msg. no: M19A
Flight id: GS0001
Message content:-
(2AAACN39320W089217ASE GJT MBS GRR LAN -/A(Z
-----------------------------------------------------------[04/01/1998 13:10]

This automatically-generated position report format gives the current position of the aircraft (N390124 W0780427), altitude (ALT 09984 feet), static air temperature (SAT -014 C), the wind direction and velocity (WND 307 degrees at 014 kts.), an entry position for true air temperature (TAT, in this example there is no entry), true air speed (TAS 309 kts.), crusing speed in Mach (CRZ Mach .61 ), fuel on board (FOB 30400 lbs.), date (DAT 971230), and the time of the report (TIM 0847:11 UTC).

ACARS mode: 2 Aircraft reg: .N425FE
Message label: 16 Block id: 8 Msg. no: M27A
Flight id: FX1018
Message content:-
301101/AUTPOS/LLD N390124 W0780427
/ALT 09984/SAT -014
/WND 307014/TAT ****/TAS 309/CRZ 061
/FOB 030400 UTM LB
/DAT 971230/TIM 084711
-----------------------------------------------------------[30/12/1997 08:47]

 

Northwest (NW) flight 444 is enroute La Guardia (LGA) to Detroit-Metropolitan (DTW) and was overhead waypoint DARBO at 1218 UTC, at flight level 350 (35,000 feet), and is estimating arrival at DTW 1319 UTC. The onboard weather is a minus 50 degrees C, the winds are 245 degrees/132 knots, and the fuel remaining is 18.7 or 18700 lbs. Free text describing the ride conditions follows.

ACARS mode: 2 Aircraft reg: .N321US

Message label: 17 Block id: 6 Msg. no: M10A

Flight id: NW0444

Message content:-

301217 LGA DTW1

LGA DARBO 1218 350 DTW 1319 M50 245 132 0 018700

0000

LT CHOP BETWEEN FL260-

FL305 DURING CLIMB. SMOOTH ABOVE.

----------------------------------------------------------[30/11/1997 12:20]

This is the Atlantic Coast Airlines version off an off report. Embedded in the message is the departure station (KIAD-Washington Dulles) and the destination (KRDU-Raleigh/Durham):

ACARS mode: 2 Aircraft reg: .N472UE
Message label: 1L Block id: 9 Msg. no: M08A
Flight id: DH6598
Message content:-
(2AAADN38529W077268QF6598KIAD1205KRDU(Z

Although not officially confirmed, the message label 24 is believed to be used for weather and/or ATIS requests for Northwest Airlines aircraft. The message shows the date and time of the request (041924) and the requested cities, in this case Chicago Midway (MDW) and Minneapolis (MSP).

ACARS mode: 2 Aircraft reg: .N926RC
Message label: 24 Block id: 3 Msg. no: M01A
Flight id: NW1089
Message content:-
041924 MDW MSP0
MDW MSP
-----------------------------------------------------------[04/01/1998 13:24]

This UPS format position report can be broken down as follows: date of flight (30), followed by the time of transmission (0826 UTC), the flight routing (Philadelphia International (PHL) to Roanoke Regional (ROA), position (P North 395459 West 0760518), followed by the wind direction and velocity in kts. (187 degrees 030 kts.), altitude (36, 502 feet), and finally the fuel remaining (26.7) .

ACARS mode: 2 Aircraft reg: .N912UP
Message label: 30 Block id: 6 Msg. no: M79A
Flight id: UP0374
Message content:-
300826 30PHL ROA P395459M0760518////187030////////03650264////0267
-----------------------------------------------------------[30/12/1997 08:26]

Another example of a Northwest format, this one reporting the weather on board for the last five reported positions. Position(N42039 W082392) is given followed by time of transmission in UTC (1812), then altitude (212, 343, etc.), air temperature in -C (153, 453), and last but not least wind direction and velocity (252 degrees at 022kts , and 280 degrees at 055kts etc).

ACARS mode: 2 Aircraft reg: .N536US

Message label: 31 Block id: 4 Msg. no: M53A

Flight id: NW1778

Message content:-

121831 DTW PHL0

N42039W0823921812212-15325202200

N41271W0813591819343-45332805500

N40381W0804061827370-52534505700

N40232W0792601834338-44834706700

N40195W0780831842275-32528702000

-------------------------------------[12/10/1997 18:44]

 

This message not only signifies that the flight is in range of the destination airport, Detroit-Metropolitan (DTW), but also serves as a crew downlink request for planned runway conditions. In this case the flight crew has selected Runway 03L at DTW as the planned arrival runway, and the uplinked response to this message will contain any pertinent information regarding the runway, i.e. landing length available, Runway Visual Range (RVR), braking action reports, and any other current NOTAMS (NOTices to AirMen).

ACARS mode: 2 Aircraft reg: ...N93S
Message label: 36 Block id: 3 Msg. no: M70A
Flight id: NW1123
Message content:-
042036 MSN DTW0
R 03L T W M HWN A F - C

-----------------------------------------------------------[04/01/1998 14:05]

Here is an example of a Northwest Airlines Boeing 757 arrival/free text request message. Note the departure airport (DTW) and the destination airport (PHL) in line one of the message; 1912 N refers to the UTC time of arrival.

ACARS mode: 2 Aircraft reg: .N536US

Message label: 39 Block id: 3 Msg. no:M52A

Flightid: NW1778

Message content:-121839 DTW PHL1

1912 N

PLZ GIVE ETA TO HOLIDAY

INN STADIUM THX

-----------------------------------[12/10/1997 18:43]

 

This message format is believed to be an Estimated Time of Arrival (ETA) Report for UPS Flight Operations in New Jersey (NJ). UPS flight 2873 is enroute Phoenix (PHX) to Philadelphia (PHL) and is estimating arrival at 1831 UTC.

ACARS mode: 2 Aircraft reg: .N319UP
Message label: 3F Block id: 5 Msg. no: M71A
Flight id: UP2873
Message content:-
181802 18PHX PHL 1831NJ
-----------------------------------------------------------[18/12/1997 18:03]

UPS free text message format. Day of operation (11) followed by message transmission time (0500 UTC), 0355331/2322XL00 are possible maintenance report codes, and then the nature of the maintenance report.

ACARS mode: 2 Aircraft reg: .N309UP
Message label: 3G Block id: 8 Msg. no: M05A
Flight id: UP0125
Message content:-
110500 11JFK RFD 0355331/2322XL00ACARS SCREEN WENT BLANK...FMC/ACARS OPERATIN
GNORMAL
-----------------------------------------------------------[11/12/1997 05:01]

This message is believed to be a flight plan routing message, the flight in question enroute Philadelphia (PHL) to Jacksonville (JAX) on day 30 of the month (30), with time of transmission in UTC (0817):

ACARS mode: 2 Aircraft reg: .N444UP
Message label: 3J Block id: 3 Msg. no: M50A
Flight id: UP0328
Message content:-
300817 30PHL JAX
-----------------------------------------------------------[30/12/1997 08:17]

Although this is pure speculation, this is believed to be a UPS format maintenance message, complete with the full day's routing for the aircraft in question.

ACARS mode: 2 Aircraft reg: .N319UP
Message label: 3S Block id: 6 Msg. no: M69A
Flight id: UP2873
Message content:-
181754 18PHX PHL KPHL 0000000ME1651
-----------------------------------------------------------[18/12/1997 17:55]

Any message uplinked to a UPS aircraft which requires acknowledgement will be sent back in its entirety, with any necessary crew comments at the top of the message. In this case the crew has simply sent back the latest Hamilton (YHM) METAR:

ACARS mode: 2 Aircraft reg: .N209UP
Message label: 3U Block id: 0 Msg. no: M30A
Flight id: UP6006
Message content:-
A100922 10PHL YHM 37SDFDI5X 000 SDFDI5X UPS6006 /10 PHL-YHM
YHM SA 0900 E21BKN 100OVC 15 0/M/0612/982
BST RDGS SANDY

ACK REQUIRED
KUEHN, SANDY /09:21:43

-----------------------------------------------------------[10/12/1997 09:22]

ACARS mode: 2 Aircraft reg: .C-GBHZ
Message label: 4A Block id: 8 Msg. no: M24A
Flight id: AC0817
Message content:-
ORD YYZ

-----------------------------------------------------------[10/12/1998 13:23]

Here's an example of take-off configuration data being sent to an Air Canada B767. In this case it states the Fuel on Board (FOB), the Zero Fuel Weight of the Aircraft, and the Take-Off Weight (TOW). In the next section it gives the reccomended STABilizer trim setting along with other information about the passengers and cargo on board.

ACARS mode: 2 Aircraft reg: .C-GAUE
Message label: 4M Block id: O Msg. no: 7 6
Flight id: 2 55
Message content:-

FOB - 25.8
ZFW - 111.9
TOW - 137.3
STAB - 6.0

OPEN BAYS YES
LIVE NO
DDG NO
MALE/FEMALE/CHILD WEIGHTS USED
SPL RMKS NO

AGT KANE/PETER
-----------------------------------------------------------[02/03/1997 13:24]

ACARS mode: 2 Aircraft reg: .C-FYIY
Message label: 4Q Block id: 8 Msg. no: M28A
Flight id: AC0551
Message content:-
TDX AC0551/30/30 DCA 1129Z 1138Z 252
0112/002685 U A
-----------------------------------------------------------[30/11/1997 11:38]

This departure report from an Air Canada Canadair Regional Jet is an example of Air Canada's own ACARS formats. Note the departure station (IAD) and the destination (YOW), and again , the flight number AC0333 are embedded in the message.

ACARS mode: 2 Aircraft reg: .C-FXMY
Message label: 4R Block id: 8 Msg. no: M48A
Flight id: AC0333
Message content:-
C32AVT 1OSVFL AC0333/12/12 IAD YOW 124 1835Z 026/0022/0001 T
05/01910169 /154232/P23P19/ /08520850/784779/09330928/02740273/
/091090/7882/076065/0 00 /0 00
-----------------------------------------------------------[12/10/1997 18:38]

This is a relatively new message that shows the valid ACARS frequencies that an Air Canada flight will use during its flight:

C-GAUW BOEING 767
AIR CANADA AC0985
Using Ground Station 2 .Message No. 2402
Message Type 4X
4C MQ5 -MFT C080 608/AC131475Y/
131550N/XA131550N/XS131725N/XS131550N/JD131450N

The airborne subsystem is requesting that the ACARS clock be updated to current time UTC (GMT)

ACARS mode: 2 Aircraft reg: .N486UE
Message label: 52 Block id: 1 Msg. no: M00A
Flight id: DH0001
-----------------------------------------------------------[09/12/1997 08:26]

ACARS mode: 2 Aircraft reg: .N19623
Message label: 5D Block id: 3 Msg. no: 5534
Flight id: CO1041
Message content:-
30KIAH
-----------------------------------------------------------[30/11/1997 11:55]

Here is another example from a UPS 727 freighter requesting weather for Hartford Bradley International (BDL):

ACARS mode: 2 Aircraft reg: .N208UP
Message label: 5D Block id: 4 Msg. no: M48A
Flight id: UP0122
Message content:-
BDL C
-----------------------------------------------------------[30/12/1997 09:29]

This message type has many variations to it. First, here is a very simple US Airways message format for weather requests, in this case requesting the latest weather for Pittsburgh (PIT).

ACARS mode: 2 Aircraft reg: .N809US

Message label: 5U Block id: 7 Msg. no: 3654

Flight id: US0302

Message content:-

1 PIT

Here's an example of a weather request message (WXRQ) from a Delta 757, in this case requesting latest weather for station (STA) KATL-Atlanta. After receiving this request, the ground station will uplink the report requested.

2 .N611DL 5U 0 1324 DL0621

01 WXRQ 0621/29 KLGA/KATL .N611DL

/TYP 1/STA KATL/STA /STA

-----------------------------------------------------------[29/01/1997 20:13]

There are several examples of a 5Z message:

Example 1: Here's an ALT (ALTimeter) report from an American Airlines 767. You can easily see that it is inbound Chicago-O'Hare, the ORD altimeter is 3011, and the ETA into ORD is 0210 UTC. OS stands for Other Supplementary information, which in American Airlines' format indicates the destination airport.

ACARS mode: 2 Aircraft reg: .N861AA
Message label: 5Z Block id: 4 Msg. no: 3649
Flight id: AA0240
Message content:-
OS ORD /ALT30110210
-----------------------------------------------------------[22/10/1997 20:38]

Example 2: Here's a report from a TWA MD83 informing operations that the flight is on time (FOT), departure airport (DA) is BWI (Baltimore-Washington International), and that the fuel on board is 22.1.

2 .N9304C 5Z 6 0213 TW0561

FOT/DA BWI/FB 0221

-------------------------------------------[29/01/1997 20:03]

In example 3, the crew uses ACARS to send a free text message for critical items such as football scores for the passengers:

ACARS mode: 2 Aircraft reg: .N582UA
Message label: 5Z Block id: 5 Msg. no: M88A
Flight id: UA1585
Message content:-
/C4 BOSDEN ANY SCORES ON THE GRN B
AY/TMPA BAY GAME?

-----------------------------------------------------------[04/01/1998 12:42]

Example 4 shows the crew advising dispatch of holding situation:

ACARS mode: 2 Aircraft reg: .N330UA
Message label: 5Z Block id: 3 Msg. no: M40A
Flight id: UA1131
Message content:-
/C4 MIAORD WILL HOLD AT HALIE-
EFC 1928Z. CAN WE USE
A CLOSER ALTERNATE ?

-----------------------------------------------------------[04/01/1998 12:58]

For more details on United Airlines 5Z messages and the parameters used in the message content, click here.

Here is an example of a regularly transmitted postion report. The KBOS/KCVG indicates that it is going from Boston to Cincinatti Oh. Both Delta and Canadian use this format. The report passes along the following information:

/POS Position VOR PSB

/NXT CVG Next station is Cincinatti

/ETA 1325 is planned arrival time in UTC

/ALT is current altitude of FL350

/FOB is Fuel on board at 31,200lbs

/SAT 50 is static air temperature at (-)50C

/WND Current winds are 237 degrees at 130kts

/MCH 84 is current Mach number of .84

/TRB is current air stability...smooth

/SKY undercast (cloud solid below)

/ICE Current icing conditions- none

 

ACARS mode: 2 Aircraft reg: .N109DL

Message label: 80 Block id: 5 Msg. no: M78A

Flight id: DL0745

Message content:-

3C03 0745/30 KBOS/KCVG

/POS PSB /OVR 1211/NXT KCVG /ETA 1325

/ENS /ALT 350/FOB 0312/SAT 50

/WND 237130/MCH 84/TRB SMOOTH /SKY UNDERCAST/ICE NONE

---------------------------------------------------------------[30/11/1997 12:11]

Similar Canadian example:

ACARS mode: 2 Aircraft reg: .C-FDCA
Message label: 80 Block id: 3 Msg. no: 5311
Flight id: CP0989
Message content:-
3C01 POSWX 0989/04 CYYZ/CYVR .C-FDCA
/POS BAE /OVR 1951
/ALT 310/FOB 0294/MCH 782/SAT 50
/POS DLL /OVR 2002
/POS
/WND 250/75/TRB SMOOTH /SKY UNDERCAST
-----------------------------------------------------------[04/01/1998 13:53]

Here is an example of a Scandanavian Airlines crew manually reporting a maintenance problem via free text entry into ACARS.

ACARS mode: 2 Aircraft reg: .OY-KDL
Message label: 84 Block id: 1 Msg. no: M41A
Flight id: SK0941
Message content:-
3E02 SNAG 0941/03 EKCH/KORD .OY-KDL
/FAL 00000000
PAX VIDEO CHARGING U/S
IN FWD GLY AND LEFT SIDE
IN FWD CBN.
-----------------------------------------------------------[03/01/1998 12:10]

 

Here is an example of the Automatic Terminal Information System (ATIS) data being uplinked to a United B727.

 

ACARS mode: 2 Aircraft reg: .N7252U
Message label: 8X Block id: 2 Msg. no: 0631
Flight id: UA1468
Message content:-
/HDQDLUA.RA CMD 18, 36
CLSD. PILOTS USE CTN
FOR BIRD ACTIVITY I
-----------------------------------------------------------[05/01/1999 09:08]

In this message, British Airways flight 2242 enroute Mexico D.F. to London-Gatwick has sent a message to Gander Center (YQXXRAC) to request oceanic clearance. The flight is estimating arrival time at oceanic entry point 49North 50West (49N050W) at 0827 UTC, requesting Mach .85 (M085) and Flight Level 370 (F370) for the crossing:

ACARS mode: 2 Aircraft reg: .G-CIVK
Message label: B1 Block id: 7 Msg. no: 0351
Flight id: BA2242
Message content:-
/YQXXRAC.-49N050W/0827 M085F370
-----------------------------------------------------------[30/12/1997 06:04]

ACARS mode: 2 Aircraft reg: .N317UP
Message label: B9 Block id: 6 Msg. no: M38A
Flight id: UP0610
Message content:-
TI2/024ORD ACB5A
-----------------------------------------------------------[30/12/1997 09:48]

This message type is initiated on the ground and uplinked to the ACARS printer in the cockpit. In the example below, the message contains the Air Traffic Control clearance for an American MD80 from Los Angeles to Chicago.

ACARS mode: 2 Aircraft reg: .N564AA
Message label: C1 Block id: J Msg. no: .TUL
Flight id: DDAA 0
Message content:-
31350 FROM 50 50
AGM
AN N564AA/AP LAX
- FLIGHT 2098/03 LAX -ORD
PDC
AAL2098 XPNDR 7316
T/MD80/A P1415 330
LAX LAXX2 TRM PKE J78 DRK
J96 IRK BDF3 ORD
MAINTAIN 2000
DEPT. FREQ. 124.3
-----------------------------------------------------------[03/03/1997 05:49]

These messages are used to transmit various flight and/or engine performance data as well as Navigation and other parameters. Different airlines appear to use different formats and codes.

The H1 message usually reflect data dumps from the flight data recorder (DFDAU) ,the flight management computer (FMC) or the Central Fault Data Indicator (CFDIU). All messages generated by these on board systems are preceded with the "#" character and a two letter code that defines which system was the source of data for the message. Typically, #CF indicates that the source was the CFDIU, #DF for the DFDAU and #M1 or #M2 for the FMC. In addition, a fourth character is displayed as either an A or B to indicate if the message is in the conventional (A) or conversational (B) mode.

The string of text that appears beyond the 4 characters described above gives an even better clue as to the nature of the message. Here are some examples and their associated meanings:

#CFBFLR or #CFBWRN = Equipment failure

#DFB*TKO or #DFBTKO = Take off performance data

#DFB*CRZ or #DFBCRZ = Cruise performance data

#DFB*WOB or #DFBWOB = Weather observation

#DFB/PIREP = Pilot Report

#DFBEDA or #DFBENG = Engine Data

#M1AAEP = Position/Weather Report

#M2APWD = Flight plan predicted wind data

#M1BREQPWI = Predicted wind info request

Below is an example of a cruise report featuring mostly engine performance data from a Continental Airlines 757 enroute Newark (KEWR)-Lima (SPIM). Note the #DFBCRZ indicating that the data was derived from the DFDAU and contains cruise performance data. Notice the five numbers after the three number sequence separated by dashes? That's the present altitude, in this case FL310, followed by the speed in Mach, the next three numbers or .800.

2 .N19117 H1 0 4656 CO0703

#DFBCRZN19117KEWRSPIM2901204614 313-2275-513 30996080022408007031SCR1C

E211 031407031408 826 830 785 789 825 825543546 4064 406414881494 94

6 953 74 771001021972060360240070110100690000011000 80002970416022

-----------------------------------------------------------[29/01/1997 20:46]

A typical weather report format for the last four programmed positions for this United Boeing 737-300

2 .N334UA H1 3 D59A UA0245

#DFB/WXPACUA./WX LGADEN5

3340A0245/29LGADEN

N40483W0751671956P26036M380271080P097

N40470W0752321957P28000M425264078P105

N40448W0753161958P30024M478261080P094

N40449W0764802008P30992M505263077P095

--------------------------------[29/01/1997 20:08]

An example of the most frequently transmitted ACARS message. Typically there is no message content with this type of message.

ACARS mode: 2 Aircraft reg: .N10236

Message label: Q0 Block id: 8 Msg. no: 5752

Flight id: CO0563

-----------------------------------------------------------[15/10/1997 12:58]

We see here that TWA flight 429 was off the gate Baltimore-Washington International (BWI) at 1401 UTC and departed BWI at 1411 UTC. St. Louis (STL) is estimated at 1615 UTC and fuel is 31.3.

ACARS mode: 2 Aircraft reg: .N54325

Message label: Q1 Block id: Msg. no: 1210

Flight id: TW0429

Message content:-

BWI14011411 0313STL/ET 1615

-----------------------------------[02/12/1997 14:11]

Here is a report from a Continental MD-80 giving their ETA at West Palm Beach International (PBI) as 2321 UTC.

ACARS mode: 2 Aircraft reg: .N14890

Message label: Q2 Block id: 3 Msg. no: 2433

Flight id: CO0626

Message content:-

PBI2321

-----------------------------------------------------------[11/12/1997 21:25]

This message is sent from the aircraft to the ground when the onboard systems cannot process an uplinked message:

ACARS mode: 2 Aircraft reg: .N867AA

Message label: Q5 Block id: 0 Msg. no: 2648

Flight id: AA0804

-----------------------------------------------------------[11/12/1997 21:28]

This message initiates a connection from the aircraft to the ACARS subsystem where prior communications between the airline and the aircraft were done via voice.

ACARS mode: 2 Aircraft reg: .N619UA

Message label: Q6 Block id: 0 Msg. no: S20A

Flight id: UA0050

-----------------------------------------------------------[30/11/1997 11:41]

In this example, American flight 804 is inbound Newark International (Note the OS/EWR part of message) but has been given a hold at waypoint HOLEY, EFC (Expect Further Clearance) at 2155 UTC.

ACARS mode: 2 Aircraft reg: .N867AA

Message label: Q7 Block id: 9 Msg. no: 2645

Flight id: AA0804

Message content:-

OS EWR /EFC2155HOLEY

-----------------------------------------------------------[11/12/1997 21:28]

United flight 1586 departed New York-La Guardia (LGA) at 1419 UTC. This message is initiated automatically when all doors are closed and the parking brake is released, which indicates a departure from the gate.

ACARS mode: 2 Aircraft reg: .N413UA

Message label: QA Block id: 2 Msg. no: M99A

Flight id: UA1586

Message content:-

LGA1419

-----------------------------------------------------------[21/11/1997 14:38]

An example of a QB report (using Atlantic Coast-designated message label 1L)

ACARS mode: 2 Aircraft reg: .N319UE

Message label: 1L Block id: 4 Msg. no: M03A

Flight id: DH0001

Message content:-

(2AAABN38597W077277QB 1256(Z

-----------------------------------------------------------[15/10/1997 12:59]

USAir flight 271 arrived New York-La Guardia (LGA) at 1258 UTC. This message is initiated when the aircraft touches down and the nose gear remains compressed for 10 seconds.

ACARS mode: 2 Aircraft reg: .N896US

Message label: QC Block id: 4 Msg. no: 5852

Flight id: US0271

Message content:-

LGA1258

------------------------------------[11/12/1997 19:44]

United 1586 has arrived Washington Dulles International (IAD) at 1436 UTC. The message is sent automatically once the aircraft has arrived at the gate, the parking brake is set, and at least one of the doors have been opened.

ACARS mode: 2 Aircraft reg: .N413UA

Message label: QD Block id: 1 Msg. no: M98A

Flight id: UA1586

Message content:-

///1436

-----------------------------------------------------------[21/11/1997 14:38]

USAir flight 2310 is enroute Washington National (DCA) to Boston Logan Int'l (BOS) with fuel onboard 19.3.

ACARS mode: 2 Aircraft reg: .N812US

Message label: QE Block id: 0 Msg. no: 0011

Flight id: US2310

Message content:-

DCA 0193BOS/DC

-----------------------------------------------------------[04/08/1997 22:33]

Here is an OFF message from a Challenger 601 corporate jet. Note that the coordinates place this aircraft on departure from Washington Dulles International. The off time is noted in the message as 2233 UTC.

ACARS mode: 2 Aircraft reg: ..N94BA

Message label: 15 Block id: 5 Msg. no: M04A

Flight id: GS0001

Message content:-

(2N38568W 77366OFF------22330909 010(Z

-----------------------------------------------------------[14/09/1997 22:37]

Here is an OFF message at the moment of departure from Baltimore-Washington International from a British Airways 767-300ER

ACARS mode: 2 Aircraft reg: .G-BNWR

Message label: 10 Block id: 7 Msg. no: 3358

Flight id: BA2194

Message content:-

OFF012233

-----------------------------------------------------------[14/09/1997 22:33]

 

An OFF report from an American Airlines B757, using the format departing airport (IAD)/time off (2018 UTC)/destination airport (LAX).

2 .N681AA QF 1829 AA0143

IAD2018LAX

------------------------------[29/01/1997 20:18]

An OFF report from a US Airways DC9; FP refers to planned flight time, CO is the Captain's company ID code, FO is the First Officer's code, and the A1/A2/A3 codes are for the flight attendants.

ACARS mode: 2 Aircraft reg: .N971VJ

Message label: QF Block id: 8 Msg. no: 3342

Flight id: US1427

Message content:-

IAD1234PIT/FP 040/CO 10030/FO 62085/A1 41850/A2 54529/A3 42356

-----------------------------------------------------------------[30/11/1997 12:33]

This message format is sent by the airborne subsystem to indicate that the unit could not process the message previously uplinked:

 

ACARS mode: 2 Aircraft reg: .C-FYIY

Message label: QX Block id: 2 Msg. no: S54A

Flight id: AC0551

-----------------------------------------------------------[30/11/1997 11:53]

The RA message is sent to the aircraft as a command to perform certain functions using the ACARS system as a gateway to other onboard systems. If for example, the company dispatch wanted to update the flight plan stored in the Flight Management System, it could do so via this message type.

Here's a United Airlines 757 receiving gate information for Chicago-O'Hare:

ACARS mode: 2 Aircraft reg: .N506UA

Message label: RA Block id: B Msg. no: QUHD

Flight id: QWDUA~

Message content:-

1GATE ASSIGN

UA881 IADORD

GATE C21 FREQ 130.15

EON 1602 APU OFF

ACARS mode: 2 Aircraft reg: .N767UA

Message label: RB Block id: 2 Msg. no: M16A

Flight id: UA0914

Message content:-

QUHDQDDUA/~2 0914 IADCDG 2224-2236/---------

8180 DENIAD 1707-1719/2001-2007

0000 ------ 1442-----/-----1449

-----------------------------------------------------------[02/08/1997 22:40]

United Airlines 5Z messages contain an additional parameter at the beginning of the message content field that gives further clarification as to the purpose or destination of the message. Note in the message below, the /CS parameter after the flight id field and at the beginning of the message content field:

ACARS mode: 2 Aircraft reg: .N991UA
Message label: 5Z Block id: 7 Msg. no: 5746
Flight id: UA1690
Message content:-
/CS GRRORD NEED 4 WHLCHRS & HAVE 4
UM'S
----------------------------------------[02/01/1998 13:58]

In this case, the /CS indicates that the message is regarding a customer service issue, and has been routed to the appropriate terminal at United. Other known parameters and their definitions are as follows:

/B1 Request Weight and Balance

/B3 Request Runway Data

/CD Weight and Balance

/CG Request Pre-departure clearance (PDC)
/CM Crew Scheduling

/C3 Off message

/C4 Flight dispatch

/C5 Maintenance Message

/C6 Customer Service

/10 PIREP

/C11 International PIREP

/DS Late message

/D3 Holding pattern message

/D6 From-to +date

/D7 From-to+Alternate+Time

/EO In range

/PW Position weather

/RL Request Release

/R3 Request howgozit message

/R4 Request the latest POSBD

/TC From-to-fuel

/WB From-to

/W1 Request weather - City