QUOTE(Fast Jet @ Jan 25 2011, 05:02 AM) [snapback]132881[/snapback]
If you have ACARS capable of uplinking and downlinking, just about everything you want to receive and transmit about the flight, in text form (but not always) . . . .
Why is there SATCOM? for things like CPDLC or are they both the same thing?
What happens if the internet is down with SATCOM?
ACARS basically provides information. Our Phase III system will give us all of the basic stuff (ATIS, WX, connections to dispatch and mechanics and a bunch of other things) plus things like clearances from ATC.
CPDLC is a whole different monster. The fast and easy answer is that CPDLC is dependent on SATCOM. No SATCOM, no CPDLC. Without getting into 30 minutes worth of typing to explain it all, CPDLC has basically two different functions. One is position reporting. Once we plug into the system and do all the magic from our end, we don't have to make verbal position reports. That's a huge thing. No more trying to reach Rangoon radio on nights where the HF reception sucks. The CPDLC system via SATCOM does it automagically for us. The second function is kind of a virtual radar thing. The onboard computer basically marries up to the ATC computers and they have an ongoing conversation. As a result of that, the ATC computer system is able to determine the position of our airplane in environments where there is no regular radar coverage. In reality it's a lot more complicated than that but that gives you the quick and dirty explanation.
SATCOM has nothing to do with the internet. One more really good thing about SATCOM. It acts like a phone. If I'm flying over Outer Screwedupistan and I have a problem I can use SATCOM to literally phone home. I input the phone number for maintenance and transmit it. Within seconds I'm talking to the maintenance folks back in the world. And it's like they're sitting in the right seat with me. I could even call my girlfriend (Bluebird) but that'll tick the company off because the calls are very expensive. Cool stuff.