the top stories on al jazeera, we begin with breaking news. us authorities say all flights in the united states have been grounded because of a system failure. the federal aviation administration says more than $400.00 flights have been delayed within into or out of the united states because of a technical glitch. it s unclear what s behind this, the federal aviation administration as treated in the last few minutes and says the f e a is working to restore its notice to air mission system. we are performing 5 final validation checks and we re roll reloading the system. now operations across the national airspeed system are affected. we re going to provide frequent updates as we make progress. or kimberly hawk at our white house correspondent is joining us on the phone. now kimberly, this is a very large scale incident. what more do we know? yeah, this is something that the biden administration is grappling to deal with right now . this is something that is unfolding in real t