The very first Boeing 777X -- the longest passenger jetliner in the world -- was revealed to the world the other day by Boeing Commercial Airplanes (BCA).

The first to get a glimpse of this overlong aircraft were Boeing employees. They got to see for themselves at this 252 foot-long plane, which is longer than its predecessor, the 777-300ER, and the super-stretched Airbus A340-600.

The Boeing 777X is the latest series of the Boeing 777 long-range, wide-body, twin-engine family. It was launched in November 2013 and comes in two variants: the 777-8 and the 777-9.

The 777-9 is 76.7 meters long while the length of the 777-8 is 69.8 meters.  Both are powered by two enormous General Electric GE9X-105B1A high-bypass turbofans specifically developed for the 777X.

This twin-engine plane will even be longer than the current record-holder: the 747-8. This is the latest version of Boeing's own "Queen of the Skies" whose ancestor flew 50 years ago.

The 777X's enormous length allows it to seat between 400 and 425 passengers in two classes. It can fly routes of more than 14,000 kilometers or 7,600 nautical miles.

The 777-8 provides seating for 365 passengers on average and has a range of 16,090 km while the 777-9 has seating for 414 passengers and a range of over 13,936 km. The -9 is expected to rake its first flight this year with deliveries to begin by 2020 at the earliest.

The 777X will become the biggest twin-engine airliner of all time when it starts flying passengers next year.

The 777-8 will seat between 350 and 375 passengers and have an endurance of more than 17 hours aloft. It is Boeing's challenger to the Airbus A350ULR's as the world's longest-range airplane.

BCA said eight airlines have placed 358 orders and commitments for the 777X. The Dubai-based Emirates will get the first 777-9 in 2020 and the 777-8 will follow by 2022. The top three airlines with firm orders for the 777X are Emirates (150 aircraft), Qatar Airways (50 aircraft) and Cathay Pacific (21 aircraft).

The new cabin wall design has the potential to allow wider seats, especially in the economy. Airlines will probably put the same economy seats on the 777X as they have on the legacy 777.

The 777X's overhead bins are larger, so passengers can better store more and more of the luggage they bring along on flights.