"Heavy" denotes a wide-bodied aircraft. A "vector" is an instruction indicating the direction in which an aircraft turns. "Pan pan pan" indicates an emergency, but is not a distress call.

Crew: Swissair One Eleven heavy is declaring pan pan pan. We have smoke in the cockpit, request deviate immediate right turn to a convenient place, I guess Boston.

Controller: Would your prefer to go into Halifax?

Affirmative for Swissair One Eleven ... prefer Halifax from our position.

A TSB note attached to the transcript indicates that at that time, the plane was 70 nautical miles from Halifax and 300 nautical miles from Boston, flying at 10,000 metres (33,000 feet).

Okay active runway at Halifax is zero six. Should I start you an vector for six.

Yes, vector for six will be fine, Swissair One Eleven heavy.

Turn left heading zero three zero.

You've got 30 miles to fly to the (runway) threshold.

We need more than 30 miles ...

... turn left ... to lose some altitude.

Roger. We are turning left.

... We must dump some fuel. We may do that in this area during descent.

Okay ...

Okay. We are able for a left or right turn towards the south to dump.

Roger. Turn left, heading of 200 degrees and advise me when you are ready to dump ...

... We are declaring an emergency at time zero one two four ... We are starting vent now. We have to land immediately.

Swissair One Eleven You are cleared to commence your fuel dump on that track and advise me when the dump is completed.

Swissair One Eleven. Check you are cleared to start fuel dump.