Slowing down the game when UFO's land?

I know it's not a big deal, but I was just wondering why not slow down the game to 5sec when the UFO's that are flying around land (become green)? Sometimes I don't react in time to slow down the game manually.

Same. Maybe it'd be too handholdy to just pop an alert box and pause ala when they pop into radar, but it'd be nice to at least have a stronger cue when one lands.