The One (2) - S1-E22
Other mistake: The captain talks about the "outflow valve", which has a distinctive rectangular shape and is fitted flush with an opening in the aircraft skin. It would be immediately recognizable by any crew member because it part of the walkaround inspection before each flight. He is holding a round pneumatic supply valve instead, which is part of the internal ductwork.
The One (2) - S1-E22
Other mistake: The tail and nose section of the crashed plane are from a 737, which has only a single axle on each landing gear. Landing gear with dual axles, from a much larger plane, can be seen in several scenes.
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