[Coop]

blowing up a nuke mid-air (for whatever reason).

It would most likely spread fall-out over a larger area, but I just think the risk of detection far outweighs any reward from a larger nuclear "footprint."

[Anti-McGovern]

Airburst would be more inherently more destructive (blast and heat effects). However, if plane is contrained to Dulles landing pattern, they would be able to detonate it w.in range to do much harm to the Federal core of DC--assuming suitcase nuke.