Transport Secretary Heidi Alexander has described the power outage at Heathrow Airport last week as "unprecedented" in a House of Commons statement.She told MPs: "What we know is that there was an unprecedented outage and that it wasn't the result of a single point of failure on the electricity transmission or distribution system.

Transport Secretary Heidi Alexander has described the power outage at Heathrow Airport last week as "unprecedented" in a House of Commons statement.She told MPs: "What we know is that there was an unprecedented outage and that it wasn't the result of a single point of failure on the electricity transmission or distribution system.