The One (2) - S1-E22
Factual error: The tail section of the crashed plane is from an early model 737, based on the curvature where the forward edge of the vertical stabilizer meets the top of the fuselage. The maximum seating capacity would have been about 130 passengers, while the number of crash victims was given as approximately twice that.
Answer: This "spirit" appears in several episodes throughout the rest of the season including the season finale. He's a "bad spirit" that is intent on keeping souls trapped on Earth. With the death of Andrea (her business partner) he wanted to make a deal with Melinda, to give him HER soul to release everyone else including Andrea to cross over.
Boobra