Here is my ideea about how the app would work:
I will try to make as few assumptions as possible till we get more info from CALLife.
I will also present what is in my mind the simplest use case, meaning no crew scheduler, no automated estimated time of arrival calculations.
You have a dispatcher human, or computer program that sends SMS messages notifying crew members of an emergency.
The crew member receives a message, must be able to identify that it came from a dispatcher and send a quick response via SMS.
We can think of the dispatcher as an android app on the chief/captain's phone which manages a list of his captains/ crew member phone numbers. Upon clicking a button a meaningfull message is sent to all crew members.
On the crew member side, we could have an android app described as below:
1. it knows who it's possible dispatchers are (the phone numbers)
2. when an sms message arrives if it is from the dispatcher it triggers an alarm and pop's up a window where you are asked to respond with your status and location and ETA. the crew member hits a button to respond and a meaningfull sms message is sent back to the dispatcher.
This i believe would be the simplest form of the app that would be usefull.
I have a lot of ideeas on extending from this but i think it's best for CALLife to give his feedback first