Could the passengers and crew of the Air-India plane from Montreal to Mumbai have been saved if the flight landed at Heathrow on time?

This is something aviation experts are discussing 20 years after the incident.

The plane was scheduled to land at 7.45 am at Heathrow. At 8.13 am, when the plane crashed into the Atlantic, off the Irish coast, the plane was due to be cleaned and refuelled.

In that case, all passengers and some crew would have disembarked and perhaps survived.

An explosion at the airport during refuelling could have caused more extensive damage. Or, the damage could have been restricted to the plane. Three of the terrorists -- two who placed bombs on the plane in Vancouver, and another who helped make the bombs -- may never be identified, investigators said.

Some people named as suspects in court testimonies will never be charged for lack of evidence.

Relatives of the victims lay wreaths at the memorial plaque in Ohawa, Canada, in 1987.

Inset: A relative garlands a plaque at the memorial.

Archive photographs: Sanjay Suri and Ron Santana