Dramatic cockpit audio captured a Southwest pilot declaring an emergency after being informed the engine cover ripped off shortly after takeoff from Denver with 143 people on board. In the audio, the pilot tells air traffic control they need an "immediate return" to Denver and that a piece of engine cowling is hanging off. Video showed the cover flapping in the wind in full view of passengers after takeoff. The pilot said the crew in the back reported the flap from the inboard side between the engine and fuselage ripped off at takeoff.