There is available trick for this mission.
Go to the Tips and tricks
Goal
The goal in this mission is stealing the Coach (bulletproof) which is located near the airport and getting speed above 50mph. After that, the bomb timer is set and from now you have to drive it for 1 minute. When your speed will reach 50mph or less, the bus will explode and mission will fail.
Earning
3000$ for driver and passenger (optional).