2
$\begingroup$

This may be a simple question, but how do airplanes know which ACARS messages are meant for them from the ground? I'm not sure how physically close planes would have to be in order for that to be an issue. Do they simply receive all ACARS transmissions in the area and the CMU checks for this information in the header and continues to route it if it has the proper header? I'm assuming the VHF doesn't perform any checks since the data is still an RF signal at that point.

$\endgroup$
0
1
$\begingroup$

Every ACARS message includes the tail number of the aircraft it is to/from. Every aircraft decodes every message that it receives and then discards any that don’t match its own tail number. Since every tail number is unique, this is mostly sufficient.

The messages also contain a flight number, if applicable, which helps to distinguish a message about the current flight vs the last/next flight that aircraft may also operate that day.

$\endgroup$
0
$\begingroup$

A typical ACARS VHF transmission.

Mode A

Aircraft B-18722

Ack NAK

Block id 2

Flight CI5118 <<< looks like an identifier the receiver can filter on

Label B9

Msg No. L05A

Message /KLAX.TI2/024KLAXA91A1

https://en.wikipedia.org/wiki/ACARS

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.