I am flying out of Tokyo tonight to spend the holiday weekend in Hawaii and try to decompress from all the nonsense surrounding the disaster situation here.
Narita Airport is operating fairly normally — it has its own generators which will keep it online through the surrounding blackouts — but most European airlines have dramatically altered their flying patterns, adding stops in Seoul, Beijing or Hong Kong. Lufthansa has stopped serving Tokyo entirely. The reason is that foreign flight crews do not want to spend a night in Narita when there is a nuclear meltdown raging just up the road, so they are instead overnighting elsewhere in Asia and operating day trips in and out of Tokyo from there.
From online fora, I have also discovered that American flight crews are agitating. They are not only concerned about radiation, but are also protesting that aftershocks disturb their sleep (posing safety concerns), and that the periodic blackouts and runs on toilet paper are making their layovers unnecessarily rough. The big problem here is that unlike the European airlines, Delta, American and United-Continental really need to keep operating direct flights to Narita, as they route almost all US-to-Asia passengers through Narita (Delta to its own connecting flights, other airlines to local JV partners’ connecting flights) and would be forced to accommodate connecting passengers on non-affiliated airlines at considerable expense if their own flights were diverted to other Asian airports.
Most governments are currently advising against non-essential travel to Japan, and I second this recommendation; there are too many variables that could combine to make Japan travel a living hell. If you really need to come here for whatever reason, plan to fly into Nagoya or Kansai.