(Image source: tnooz.com) Delta Air Lines, Inc. (NYSE:DAL) shares are climbing in the early session of trading after the airliner reported first quarter earnings that beat estimates. Excluding certain items, the airliner earned 33 cents a share in the quarter, which was four cents above estimates. Operating revenue increased 5 percent from a year ago to $8.92 billion. In addition, passenger revenue was also up. However, due to severe weather in January and February, the airliner cancelled 17,000 flights and as a result booked $90 million in revenue lost. Considering the difficult landscape of the airline industry, no wonder Delta shares are trading in the positive territory.