[Coulson nods. He's not surprised by the ease at which Bucky gets the plane ready. He just reaches for the radio and speaks into it.]

Bus to base. Bus to base. Maintenance crew's taking us out for a test flight. Will reconnect when done. Over.

[He switches the comms off and leans over towards Bucky, just enough so he can point at a a red switch under the panels] That should buy us some time. You might wanna switch that off. [It's the homing beacon for the plane.]