JS8Call is a program developed by KN4CRD and is based on the popular WSJT-X application and the related FT8 mode. Basically, the software takes the weak-signal benefits of FT8 and turns it into a keyboard-to-keyboard mode that doesn’t use canned messages and has some really nice other features including the ability to relay messages through other stations and the ability to send or store messages for another station if they aren’t currently available.
So, what does any of this have to do with emergency communications? Simply, the ability of a station to join the network of other stations and either communicate directly or through another station is a huge benefit. As HF propagation changes, the overall network changes, and routes come and go. But as long as the two stations involved can still work a common station or stations, then they should be able to work anyone and everyone on that particular network.
The ability of a station to store a message for someone and then walk away knowing that when the operator queries for messages your station will let them know of the pending message is also great. Mind you, these transmissions are generally slow, in the range of 8 to 40 words per minute (WPM), so it’s not appropriate for longer messages. But when you’re trying to get a message through rough conditions, this is the mode to use.
This is yet-another-tool in the toolbox of amateur radio. If you enjoy digital modes on HF and haven’t tried it, I would recommend testing it out.