The problem with datalink systems is they are poor substitutes for immediate control & confirmation. My co-founder Eric wrote a short piece about this: https://www.ericbutton.co/p/speech. This is why they are mainly relegated to low-urgency en-route & clearance delivery.
He’s write about the bandwidth and latency of voice, but the problem is that you can’t immediately know who should react to instructions. “GO AROUND IMMEDIATE!” - now all the pilots on frequency are wondering who’s the addressee
Also, AM voice on VHF is not full duplex and the blocking problem is very real and could be addressed potentially
interesting! have PP but haven't flown really last couple of decades.
I feel like, with proper UX in the cockpit and on the controller console, making it easy to send/acknowledge the clearance, and intrusively demanding immediate acknowledgment for important messages, with the controller able to talk to the pilot if it isn't immediately acknowledged, structured messages would save time, be more accurate, allow automated checks, i.e. be a superior substitute.
UX needs a ton of work and human factors validation, and would take 20 years to implement. But if you were starting from a blank slate it seems like the way to go!
