FACTBOX: Heathrow airport

(Reuters) - Protesters breached tight security at Britain's parliament on Wednesday, getting on to the roof and unfurling banners to protest against plans to expand London's Heathrow airport.

The protest by anti-aviation group Plane Stupid coincided with the end of a public consultation period over a third runway.

Heathrow Airport could get a third runway and a sixth terminal to help it cope with a surge in air travel, the government has said, despite opposition.

Here are some statistics about the world's busiest international airport:

* HISTORY:

-- The airport is named after the village or hamlet of Heathrow, which used to be roughly where Terminal 3 now stands.

-- It began as a tented village in 1946 serving 18 destinations with a handful of airlines making 9,000 flights a year.

-- The first departure was on New Year's Day 1946 to Buenos Aires via Lisbon, the first refueling stop on a long-haul flight to open up Britain's first air link with South America.

-- Heathrow's first terminal for short haul flights opened in 1955. Originally known as the Europa Building, it is now known as Terminal 2.

-- Terminal 1 was formally opened in 1969 by Queen Elizabeth. Terminal 3 opened in 1961 and Terminal 4 in 1986.

-- The public inquiry into the fifth terminal was the longest in British planning history, lasting nearly four years. It was submitted in February 1993 but construction did not actually begin until Summer 2002. The terminal is expected to open on March 27, 2008.

* KEY NUMBERS:

-- Heathrow serves over 180 destinations in more than 90 countries.

-- 90 airlines have made Heathrow their base.

-- There are two main runways. The northern one is 3,902 meters long. The southern is 3,658 meters.

-- According to the BAA traffic summary, 5.6 million passengers traveled through Heathrow in March 2007. Passenger numbers amounted to 67.3 million from April 2006 to March 2007.