ACARS VHF tuning, B738
 

Hello again guys and gals

I've read that one can tune frequencies on the VHF3 and use it as an audio channel by selecting frequencies via ACARS on the B738.

If so.. any hints on how?

Thanks :ok:

Just out of interest where did you read that? Although I'm no '37 driver I always thought you couldn't use VHF3 with ACARS operational (as ACARS uses a freq itself, like 131.725 etc).

Heh.. no official source I'm afraid. I bought a flashcard app with questions about the 737NG on my ipod touch. It stated it was possible, but it may just as well be wrong. I was of the same opinion as you.

Oh right ok, I did a quick FCOM/QRH search but came up with nothing, perhaps someone with a little more knowledge will chime in :ok:

The ACARS uses VHF COM3 for it's data bursts. It does not need to be tuned to any freq on the control head. VHF COM3 is useable while ACARS operates 'in the background', but will not ACARS XMIT or ACARS RECIEVE while you are voice XMITTING on whatever freq you have dialed in the control head (or FMS COM page).

You can sometimes hear the screech of the ACARS burst transmit and recieve as it happens if a 'sympathetic' freq is tuned. So happens 121.5 and 123.45 are both sympathetic.

It can also use SATCOM if so equipped and enabled; same deal, is in the background, and does not interfere with voice comms thru SATCOM.