Meaning: Start discussing a topic
Example: We didn't GET ONTO the third item on the agenda.
Meaning: Be elected, appointed
Example: He didn't GET ONTO the committee.
Meaning: Appear on the radio or TV
Example: He GOT ONTO every major channel after the accident.
Meaning: Contact someone because you need or want them to do something
Example: We'd better GET ONTO someone to fix this.
Meaning: Enter a plane, train, etc
Example: She GOT ONTO the plane just before it took off.