The jet is about the same size as a Hercules military transporter, and that's the aircraft the KC-390's makers, Embraer, have in their sights around the world - including New Zealand, which has about $1 billion to spend on its airlift and VIP fleet in the next decade.
The KC-390 that this month sat in 34C heat just off the Gaviao Peixoto landing strip is one of just two prototypes built so far. The other was being worked on in a hangar besides the strip which at 5km long was once an emergency landing spot for US space shuttles.
As of earlier this month, the pair of planes had flown just 623 hours between them when the Herald was part of a small media contingent to inspect Embraer's commercial, executive jet and defence operations, based around the southern state of Sao Paulo.
The listed Brazilian company has been making planes since 1969; it is a big global player in commercial jets with up to 130 seats, and based on its revenue from aircraft making, vies with Canada's Bombardier for the third spot behind Boeing and Airbus.
In nearly 50 years of business, Embraer has delivered more than 8000 aircraft in more than 90 countries, including the tough, small Bandeirante that flew on regional routes in New Zealand for more than 20 years to 2001.
The KC-390 was conceived in 2009 as a way of diversifying Embraer's revenue, and it has pitched the company into the medium lift market dominated by Lockheed Martin's Herc, a plane first developed in the 1950s, but whose latest model is still seen as the inside runner for New Zealand's next tactical lift purchase.
Embraer says it has been able to start with a clean sheet, and use expertise and technology from its commercial and corporate jet divisions to make a plane that can not only carry big loads, but also get places as much as a third faster than turbo-prop equivalents. It flies at up to 870km/h while still being able to use short and underdeveloped runways.
The company is also promoting its versatility, not only as a cargo carrier but also a multi-mission plane that can be used as a fuel tanker, medevac aircraft and for fighting fires, dropping paratroops and search and rescue.
Customers can also opt for a range of self protection systems, including radar warning receiver, a laser warning system, missile approach warning, and the ability to fire protective chaff and flares.
Embraer is aiming to have the KC-390 certified for military use by the end of next year, is also seeking civil aircraft certification - which it hopes to gain early in 2018 - and is already talking to one potential buyer.
The company began developing a test flight and plane manufacturing base in 2001 at Gaviao Peixoto, a sprawling 16sq km site on the high plains of Sao Paulo. Today the area is covered by 13ha of buildings and is still growing.
In one of the massive buildings, the KC-390 wing and fuselage construction line is busy assembling wings (in two parts) and the fuselage (in three parts) of planes destined for its first customer and development partner - the Brazilian Air Force, which has signed up for 28 of them. Several other defence customers are close to confirming orders.
Commercial partners in Portugal, Argentina and the Czech Republic make components for the plane, but the bulk of itis sourced from Brazil.
The gleaming assembly building is heavily populated by robots, which perform the repetitive task of precision drilling more than 60 per cent of the holes, through which they drive the titanium fasteners that hold the plane together.
Two of those planes are being made to be stretched, bent and possibly buckled in static stress tests that run around the clock in a nearby hangar. Massive weights are hung from the plane to push it to 150 per cent of its maximum tolerance.
Then there is fatigue testing of another complete plane over 45,000 hours of simulated flying - three times the estimated average lifespan of an aircraft in typical military service.
They have undergone ground vibration tests and lightning tests and are likely to end up in museums.
Like other aircraft, the KC-390 began its life in a computer, followed by the construction of an "iron bird" - a two-level steel rig covering about a third the size of a rugby field.
All the aircraft's hydraulic, avionics and flight control systems snake over this Mecanno-like structure and are run and monitored for years. On some commercial jets, the "iron bird" has been running for 15 years.
Failures and glitches can be introduced to assess how systems react and engineers can also sort out problems in real time if airborne planes need information from the ground.
Before certification, the plane will be deep frozen for days in a refrigerated hangar in Florida to test systems, operated in an Arctic environment and then tested in strong crosswinds in Southern Chile.
Development costs and tooling up assembly lines adds up to a multi-billion dollar punt for Embraer and the Brazilian Air Force, which initiated the project.
There was a hitch last year when financial problems, amid Brazil's economic slump, resulted in a reported $430 million of payments being delayed, but things are back on track now.
Jackson Schneider is president and chief executive of Embraer Defence and Security and he describes the launch into the military transport market as a "bold" step for the company, which has 17,500 employees.
"We are already in a clear and defined position in commercial aviation in the regional sphere - with the most important airlines in the world you can name, we will be there," he says.
"We have already a large presence in the business jets with a large portfolio."
More than 90 airlines in 62 countries fly Embraer commercial planes and it has sold more than 1000 executive jets around the world.
Third quarter figures reveal Embraer has slipped to a loss of $41m in the past nine months on revenue of close to $6 billion, not helped by a $291m settlement to resolve a corruption investigation by the US and Brazil, which started with an aircraft deal with the Dominican Republic, then spread to other countries, including Saudi Arabia and Mozambique.
Under the settlement, Embraer will pay more than $200m to the US Justice Department and the Securities and Exchange Commission, and enter into a three-year deferred prosecution agreement.
A spokesman told the Herald the company had "learned from this experience and will be stronger as it moves forward."
Defence makes up just over 14 per cent of the company's revenue and it has built up a market for its turbo-prop light attack fighters and trainers used by air forces around the world.
"With the KC390 it is a bold step in the defence market - it's an important step for us," says Schneider.
New Zealand defence representatives have already looked over the plane, including at Farnborough, where it was displayed to a wide audience for the first time this year.
New Zealand is emphasising its need for Antarctic operations for its next airlifter, something Embraer says the KC-390 can easily serve from Christchurch, although the long trip would almost halve its maximum load to 14 tonnes.
Brazil has its own Antarctic base, and in its huge homeland it operates in heat and humidity, as does the RNZAF in the Pacific Islands.
Schneider doesn't discuss what the plane may be worth, although a sticker price of around $120 million per plane has been reported.
"Price depends on customisation the client requires. But I can guarantee that we are very competitive considering the many missions of the plane."
Boeing will provide in-service support around the world, and Embraer says this will help sales, giving it a good shot at the New Zealand contract.
But that's not how one defence analyst in this country sees it.
While Victoria University's Peter Greener sees the appeal of the KC-390's speed, he cautions that defence forces don't like being at the front of the queue for new equipment.
The KC-390 appeared to meet the criteria for a Hercules replacement, but the Brazilian plane's lack of air miles before a likely Cabinet decision around the middle of next year counts against it, he says.
Greener, senior fellow at the university's Centre for Strategic Studies, says New Zealand is more likely to follow other air forces around the world and decide the best replacement for a Hercules is a Hercules.
Lockheed Martin isn't saying much, but points out that the C-130J Super Hercules is the proven airlifter of choice for 20 operators in 17 countries.
It would not comment on its New Zealand bid.
"We defer any questions about New Zealand's air mobility needs to the New Zealand Defence Force," a spokeswoman said.
The price of the plane depended on the number and type of aircraft ordered, training and support. There's no loose lips at the Defence Force.
"The Future Air Mobility Capability project is considering a range of options for replacing the current tactical and strategic airlift fleets (the Boeing 757s and C-130 Hercules)," a spokesman said.
"The project will deliver a capability to move cargo within the South Pacific, to Antarctica and in support of coalition operation further afield. The project is expected to deliver new aircraft to the Defence Force during the early to mid 2020s."
New Zealand First defence spokesman Ron Mark is a fierce critic of much defence procurement over the past two decades, which he says has been marred by expensive mis-steps.
The Air Force was denied a chance to upgrade its transport fleet years ago, by what he says was a disastrous move to buy light armoured vehicles, but now has the opportunity it get it right.
While the speed of the KC-390 has some appeal, the Hercules replacement is an opportunity to keep the same plane.
"We're highly disposed to the 130J. You'd have to have a damn good reason to cut away and introduce something new."
The enormous Boeing C17 Globemaster has been on the radar for several years but is now out of production and only one "white tail" - unsold - aircraft is on the market.
"Let's not be fooled into buying one great big fat elephant that can't land in places where a tactical lifter could land - if you have to fly in two tactical lifters in, so be it," says Mark.
The A400M, a high performance aircraft, is much bigger than both the Hercules and the KC-390 and its maker, Airbus, is continuing to promote the aircraft in New Zealand specialist publications, after a mainstream media "hearts and minds" campaign last year.
The A400M programme has also struck snags, but last week delivered the first of 27 aircraft to Spain, the sixth nation to put it into service.
While the timing will be tight for Embraer to meet the New Zealand timetable, its Defence and Security vice president of sales, Fernando, Queiroz says the company is nimble enough to meet it.
It can defer supplying the Brazilian Air Force if another country orders the plane, he says.
Embraer hopes to bring one of the KC-390s on a flying visit to New Zealand next year, to boost its chances of seeing its big, brawny plane stationed here permanently.
Grant Bradley traveled to Brazil with the assistance of Embraer.