Authorities say the pilot of a small, single-engine plane that made an emergency landing on a busy highway southwest of Boston had been practicing how to handle stalls.

The pilot and a passenger on board walked away. There were no other injuries in the mishap that tied up traffic on Interstate 495 for hours Tuesday.

The Federal Aviation Administration had said earlier the plane was a traffic reporting plane. FAA spokesman Jim Peters said later that it was practicing stalls by slowing down its airspeed when its engine quit.

The plane wound up nose-down with a collapsed undercarriage, taking up nearly all three southbound lanes of the highway and backing up traffic for miles.

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