SEATTLE >>  A Seattle airport worker started his shift early and ended it with a nap in the wrong place — the cargo hold of a plane taking off for Los Angeles.

When he realized what was happening, he banged on the aircraft for help, a sound the pilots and first-class passengers on the Alaska Airlines flight fortunately heard.

The plane had just left Monday afternoon when the pounding noise from below started, the airline said. The captain immediately returned to Seattle-Tacoma International Airport and declared an emergency so the plane could land right away. It was in the air for 14 minutes.

After Flight 448 landed, the ramp worker walked out of the front cargo hold, which the airline said is pressurized and temperature-controlled.

"He told authorities he had fallen asleep," the airline said.

Medics checked the man, an employee of Alaska Airlines contractor Menzies Aviation, and found he wasn’t hurt, airport spokesman Perry Cooper said.

He also was evaluated at a hospital and passed a drug test after being released, airline spokesman Bryan Zidar said. All ramp employees undergo full criminal background checks and drug tests before they are hired and are given random drug screenings, the airline said in a statement.

The airline did not identify the worker, and a Menzies Aviation spokesman did not immediately return an email request for comment.

The man had been part of a four-person team loading baggage onto the flight, working from 5 a.m. to 2:30 p.m. Monday, the airline said in a statement.

Before the plane took off at 2:39 p.m., the leader of the man’s team noticed he was missing, called into the cargo hold and called and texted the man’s cellphone without an answer, the airline said. Co-workers figured he had finished his shift and gone home.

The plane had just departed when "the passengers in first class heard banging from underneath us and a person yelling for help," passenger Jesse Sycuro told Seattle television station KING.

Passenger Robert Higgins of Jacksonville, Oregon, told Los Angeles TV station KABC that "all of the sudden we heard all this pounding underneath the plane, and we thought there was something wrong with the landing gear."

A short time later, passengers were told the plane carrying 170 passengers and six crew members was turning around.

The flight left Seattle again at 3:52 p.m. and arrived in Los Angeles at 6:29 p.m., more than an hour late, the airline said.