Maybe to be sure he get in the car add small script after chopper will be on ground and Ashford will get out from chopper:
Something like this maybe:
titlecut["","BLACK OUT",1]
~0.05
titletext ["Good morning Dr Ashford.","plain down", 1]
~4
DrAshford assignascargo hummer (for example i dont know how you neme those units in mission editor)
DrAshford moveincargo hummer
titletext ["I will take you to HQ.","plain down", 1]
~4
titletext ["","plain", 1]
~1
titlecut ["","Black in", 1]
~0.05
exit
And im not sure if he must get out from car wenn you be close to officer to end mission, if yes maybe add him to the player taem (join command) or maybe use some commend on him to force him to get out from car.
Or add him to the player team when he jump from heli. Maybe my ideas how to do this are not the best and you know better way to do this

.
Im sure you will find some good solution
