Five facts about the Boeing E4B 'Doomsday Plane'

Aucklanders could be mistakenly thinking the US president is in town this week after the arrival of a very presidential looking aircraft on Monday.

While Donald Trump wasn't onboard the so-called Doomsday Plane, it was in fact carrying US Secretary of Defense, Mark Esper, who is in the country for a brief visit.

The aircraft itself has some pretty amazing facts and history behind it.

What is it?
 

The aircraft is a Boeing E4B, a military modified version of the Boeing 747-200. By airline standards, the aircraft is old - it's first flight was in 1973.

To put that into perspective, Air New Zealand's 747 -200s, which they first flew in 1981, were retired from the airlines fleet in 2000 at the age of 19 years. The E4B is still flying at the ripe old age of 45 years.

Nuclear:
 

The Boeing E4 was built to be a mobile command post for the president of the United States, even in the event of nuclear war. It's designed to withstand the electromagnetic pulse of a nuclear explosion and remaine completely intact. Because of this, its become known as the 'Doomsday Plane'.

Protect the President:

On top of being essentially a flying bunker for the US president, the aircraft is also part of the massive, behind-the-scenes contingency planning that goes into any presidential visit.

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When the US President is visiting a city overseas using Air Force One, the Boeing E4B is deployed to an airport near his destination, should immediate evacuation be required and Air Force One is not an option.

It's as rare as Texas steak
 

There are only four of these aircraft used by the United States as part of a 'Nightwatch' programme that ensures the president's safety.

It's so rare that you can even buy a model of it.

What's with the bump?

Bumps are becoming more common on the top of aircraft. They usually house WiFi antenna for onboard internet - however, the Doomsday Plane's is a step up from that.

Given what the aircraft was built for, its bump protects a massive HF and satellite antenna for communications with the ground, even in, well, apocalyptic conditions.

Newshub.