Banshee target plane's speed is 0.3 mach, ~100 m/s, ~360 km/h. New jet engined one should have almost 0.5-0.6 mach speed ~200 m/s, ~700 km/h.
0.6 mach speed is generaly enough for this type of low level SAM missions.
Supersonic aircraft has subsonic speed during low level fighting missions.