The opportunity to "Feel the Heat
" comes later on in the mission when you are asked to use the Javelin to take out the enemy tanks on the bridge. Use the Javelin to take out the first 3 tanks approaching from the right. After that, you are allowed to progress in the mission, but instead, you should look for a 4th tank that approaches from the left. After getting the lock-on and taking it out, this will unlock.