The Bombs Away trophy in Borderlands 2 is story-related and can't be missed.
You will unlock the trophy once you complete the "Toil and Trouble" story mission.
*** Spoiler - click to reveal ***- Go to Eridium Blight
- Find Sawtooth Cauldron
- Enter Smoking Guanno Grotto
- Kill Ambush Commanders: 0/4
- Enter Main Street Reservoir
- Enter Cramfist's Foundry
- Find buzzard hangars
- Open buzzard hangar
- Destroy Boombringer (Scare Mortar and look like a badass)
- Ascend Inferno Tower (Kill Mortar)
- Destroy buzzards: 0/5
- Steal Odomo crates: 0/4
- Head to Arid Nexus