1. The passengers on board this train are heading towards Chicago.

Note: There's very little difference between "on board" and "aboard."

 2. The control panel on board the fire engine has a lot of gauges and switches.

 3. Pets are allowed on board the flight, but they must stay inside a pet carrier.

4. Get on board the plane before it leaves.

 6. Everyone on board the plane died when it went into the ocean.

 7. The people on board this boat are sleeping.

 8. They keep life vests on board for every passenger in case of an emergency.

 9. They need to bring another employee on board because the company is very busy right now.