Could the 4 hijacked planes have had an automated message system like flight AF447 which disappeared this week ?

Herblay FRANCE

bonjour ,

with the disappearing of the aeroplane AF 447 this week I have just learned that there was an automated message system on the plane sending flight parameters information to the Air France headquarters.

Can any pilot reading this tell me if the four hijacked planes on the 11th of September 2001 send automated messages in the same way to the company headquarters. If it is the case what can we learn for 911 ?



I have a keyword to add to the search 'ACARS"

Herblay france


I have a keyword to add to the search 'ACARS"

Securing ACARS: Data Link in the Post-9/11 Environment

More Holes in the Official Story: by Michel Chossudovsky see
70. On FDR, see NTSB report,“Specialist’s Factual Report of Investigation—Digital Flight Data Recorder” for United Airlines Flight 93, Feb. 15, 2002; on CVR, see FBI report,“CVR from UA Flight #93,” Dec. 4, 2003; Commission review of Aircraft Communication and Reporting System (ACARS) messages sent to and from Flight 93 (which indicate time of message transmission and receipt); see UAL record, Ed Ballinger ACARS log, Sept. 11, 2001. At 9:22, after learning of the events at the World Trade Center, Melody Homer, the wife of co-pilot Leroy Homer, had an ACARS message sent to her husband in the cockpit asking if he was okay. See UAL record,ACARS message, Sept. 11, 2001.

ACARS messages the 11th september 2001

°1 _ _ _ _ _ ajout le 10 juin 2009

History of ACARS

Prior to the introduction of datalink, all communication between the aircraft (i.e., the flight crew) and personnel on the ground was performed using voice communication. This communication used either VHF or HF voice radios, which was further augmented with SATCOM in the early 1990s. In many cases, the voice-relayed information involves dedicated radio operators and digital messages sent to an airline teletype system or its successor systems.

Introduction of ACARS Systems

The airlines, in an effort to reduce crew workload and improve data integrity, introduced the ACARS system in the late 1980s. (A few initial ACARS systems were introduced before the late 1980s, but ACARS did not start to get any widespread use by the major airlines until the latter part of the 1980s.) Although the term ACARS is often taken into context as the datalink avionics line-replaceable unit installed on the aircraft, the term actually refers to a complete air and ground system. On the aircraft, the ACARS system was made up of an avionics computer called an ACARS Management Unit (MU) and a CDU (Control Display Unit). The MU was designed to send and receive digital messages from the ground using existing VHF radios. On the ground, the ACARS system was made up of a network of radio transceivers, which would receive (or transmit) the datalink messages, as well as route them to various airlines on the network.

Note that the initial ACARS systems were designed to the ARINC standard 597. This system was later upgraded in the late 1980s to the ARINC 724 characteristic. ARINC 724 addressed aircraft installed with avionics supporting digital data bus interfaces. This was subsequently revised to ARINC 724B, which was the primary characteristic used during the 1990s for all digital aircraft. With the introduction of the 724B specification, the ACARS MUs were also coupled with industry standard protocols for operation with flight management system MCDUs using the ARINC 739 protocol, and printers using the ARINC 740 protocol. The industry has defined a new ARINC characteristic, called ARINC 758, which is for CMU systems, the next generation of ACARS MUs.

Maintenance Data Download

It was the introduction in the early 1990s of the interface between the FDAMS / ACMS systems and the ACARS MU that resulted in datalink gaining a wider acceptance by airlines. The FDAMS / ACMS systems which analyze engine, aircraft, and operational performance conditions, were now able to provide performance data to the airlines on the ground in real time using the ACARS network. This reduced the need for airline personnel to go to the aircraft to off-load the data from these systems. These systems were capable of identifying abnormal flight conditions and automatically sending real-time messages to an airline. Detailed engine reports could also be transmitted to the ground via ACARS. The airlines used these reports to automate engine trending activities. This capability enabled airlines to better monitor their engine performance and identify and plan repair and maintenance activities.