[amsat-bb] OT?? Model Rocketry

This may be off topic? I am helping a neighbor who is just getting into high power model rocketry (Tripoli) He is interested in _two way_ telemetry with his rocket and wants the downlink for the usual sensors like altitude, GPS, XYZ-attitude etc. There are _one way_ products that provide the downlink but he also wants to be able to uplink to fire parachutes or thrusters (during descent). I am leaning toward an 900 MHz ISM solution for the RF but am stumped as to what digital platform would be most flexible (and light weight) for the communications needs. Are there any standards or better yett off the shelf products? I am open to suggestions.