Name: The Runways of Fire That Let WW2 Planes Land In Fog: FIDO
Uploaded: 2020-04-01T01:10:12.000Z
Duration: 2 min 15 s
Description: Thousands of YouTube videos with English-Chinese subtitles! Now you can learn to understand native speakers, expand your vocabulary, and improve your pronunciation...

This used to be RAF Graveley, a Royal Air Force base near Cambridge.

Now, it's a farm and some wind turbines, but in the 1940s

aircraft would set off from here to fight in Europe.

And, they hoped, they'd be able to safely land back here as well.

Or, rather, smog: all the soot and air pollution from domestic coal fires

combined with fog to make an incredibly thick "pea soup".

because we don't burn smoke-producing coal in every house any more.

even runway lights wouldn't get through it

and there were no modern instruments to guide the air crews home.

By setting enormous amounts of petrol on fire.

This incredible photo shows a Lancaster bomber taking off from just behind me,

but this was how wartime airfields boiled off fog.

Set up enormous lines of petrol burners to heat up the air,

vaporise all the liquid water droplets to make steam,

which will rise out of the way and clear the air.

There are demonstration films taken by the RAF on clear days,

showing just how big and how visible this was.

that says that the glow from the fires was visible for miles.

There was a bit of smoke when they started the system up,

but once it got hot, the air could be so clear

that people on the ground could see the stars.

A small Fido system burne 70,000 gallons of fuel an hour.

One estimate says that in one foggy night over England,

all the Fido systems in use would burn 20 million gallons of fuel.

There's even a report all the extra heat pumped into the atmosphere triggered a thunderstorm.

At the current price of jet fuel, as I record this,

running a Fido system would cost about $200,000 per hour per runway.

aircraft could just not take off instead and wait for the fog to clear,

or divert to another airport if they were trying to land.

to let planes take off for battle in any weather