( CNN ) -- Air carriers are watching the situation at Japan 's Fukushima Daiichi nuclear power plant closely , making contingency plans and routing adjustments to keep operations running smoothly and protect passengers and crew from radiation risks . German airline Lufthansa and Italian carrier Alitalia have rerouted flights to and from the Tokyo area to other Japanese airports . Lufthansa 's flights to and from Frankfurt and Munich are going to Osaka and Nagoya instead of Tokyo/Narita `` in an effort to ensure that [ the airline 's ] operations to Japan remain as stable as possible and provide sufficient capacity for its passengers , '' Lufthansa said in a statement . The altered schedule is expected to last as least through the weekend . Since Sunday , the airline has been scanning aircraft returning from Japan for radiation . `` To date , none of the tests has detected any radioactivity , '' the statement said . Alitalia started rerouting all of its flights in and out of Tokyo airports to Osaka on Wednesday . Spokesman Clemente Senni said the change is designed to guarantee uninterrupted service to its passengers . Travelers will receive a refund for the trip between Tokyo and Osaka , Senni said . `` We are obviously testing planes for radiation , but nothing has been registered so far , '' he said . British Airways is routing its Tokyo flights through Hong Kong for a brief stopover , and its flights bound for Tokyo 's Haneda Airport will now land in Narita instead . Tokyo is more than 150 miles from the damaged nuclear power plant in Fukushima . U.S. airlines are in close contact with the Federal Aviation Administration and other agencies and regulators in the U.S. and abroad , monitoring conditions around the nuclear facility , according to the FAA . American Airlines is operating its normal schedules in and out of Tokyo 's airports , according to spokesman Tim Smith . The majority of customers have traveled as scheduled , he said . `` At this point , we 're monitoring things very closely and have not made any immediate decisions to change , '' Smith said . Delta and Continental airlines did not respond to requests for comment Wednesday afternoon . Japanese aviation authorities have imposed a no-fly zone within 30 kilometers ( about 19 miles ) of the Fukushima Daiichi plant . The FAA is alerting pilots to that restriction , spokeswoman Laura Brown said . On Wednesday , the U.S. Nuclear Regulatory Commission advised U.S. residents within 50 miles of the Fukushima reactors to evacuate . The commission 's statement did not reference airspace . Representatives from the Allied Pilots Association , the union that represents American Airlines pilots , said its members , flight attendant union members and others are working closely with American Airlines management to make contingency plans should the situation at the reactors deteriorate . `` What we 're hearing at Narita is basically things are pretty normal , '' said Captain Sam Mayer , the association 's communications director . The real concern , he said , will come if the situation worsens . First Officer Scott Shankland , a national union representative , said he believes the airline is in a good position to react to new developments . Mayer and Shankland said government security officials routinely scan U.S. airliners for radiation as part of normal operations . On Wednesday afternoon , U.S. Customs and Border Protection said it was monitoring the situation in Japan carefully . `` Out of an abundance of caution , CBP has issued field guidance reiterating its operational protocols and directing field personnel to specifically monitor maritime and air traffic from Japan , '' the agency said in a statement . `` No aircraft entering the United States today tested positive for radiation at harmful levels , '' it said .
Lufthansa and Alitalia have moved Japan departures and arrivals out of Tokyo . American Airlines continues to operate its normal operations in Tokyo . Customs , other agencies and regulators are in close contact with airlines , Japanese airlines . U.S. Customs : No aircraft entering U.S. today found to have ` ` emissions at harmful levels ''