America’s number three airline, Delta, has filed for bankruptcy protection. It follows in the footsteps of United Airlines, US Airways and Northwest Airlines, which made the move within minutes of Delta.All have been hit by high oil prices and competition from low-cost carriers. The latest filings mean nearly half of US airline capacity is now operating under Chapter 11 bankruptcy protection. The situation marks a new low in the airline sector’s financial crisis dating back to the September 11th terrorist attacks. It is estimated the industry posted a net loss of around 32 billion dollars, or 26 billion euros between 2001 and 2004.