International air and sea efforts to send aid to Haiti are facing huge obstacles in delivering both workers and goods to the earthquake-ravaged country. A large part of the delay stems from traffic on airport runways and at damaged ports, and experts are warning that it could take days until relief is flowing freely into the country. The news comes as the Red Cross estimates that up to 50,000 people have been killed, with thousands more still missing. Traditionally, relief efforts identify a 72-hour window of opportunity to find survivors and save lives, but aid agencies are frantic in the wake of news that help may not arrive in time. Port-au-Prince’s airport has been overwhelmed with air traffic since the quake, and the FAA has agreed to keep any planes headed for the disaster zone from taking off. A team of 35 rescue workers from England was turned around today after circling for 30 minutes above the airport. Bodies are said to be lining the streets, and many injured are roaming the streets of the capital in search of help—but little is to be found at the moment. Only a few hospitals were not destroyed, but they cannot accommodate all the injured. President Obama and many other world leaders have pledged support, but it appears as though the window for finding survivors may be closing.