To maximise survivability the seat needs to be able to orient itself optimally, then you need a number of sensors reading air speed, temperature, air pressure,

To maximise survivability the seat needs to be able to orient itself optimally, then you need a number of sensors reading air speed, temperature, air pressure, and acceleration to determine when the best time for each sequence step is. For instance, you don't want to deploy the drogue while the rockets are still firing. You also don't want to deploy it if the seat is oriented in the wrong direction and the drogue might get stuck in the seat. Then, you don't want to release the main chute until the seat has stabilised and the speed is right. You also want to control the speed of release and inflation depending on the altitude at which the ejection happened, with a more rapid release at the lowest altitudes. Early seats used simple delay fuses and didn't have the ability to sequence events based on sensor inputs, resulting in a lot more post-ejection deaths and injuries.