Disappearing Into Thin Air
The flight eventually landed in Seattle, Washington, and Cooper got what he had asked for. He released all the 36 passengers when the authorities handed over to him the money and the parachutes. But then he did something that he didn’t actually request in his ransom note. He forced two pilots, a flight engineer and a flight attendant to stay on the plane and not exit with the rest.
Source: The AV Club
The plane was refueled, and he ordered the pilots to fly to Mexico City. He made sure they flew under 10,000 feet and at a speed slower than 200 knots. Around 8:00 PM, between Seattle and Reno, Cooper lowered the rear steps and jumped out. He literally disappeared into thin air.