Perhaps it’s an ultra-modern jet like Qantas’ brand-new Dreamliners, the first of which triumphantly arrived from the Boeing factory amid much pomp and ceremony just a few months ago.

Or if the plane not quite factory-fresh — older aircraft can still fly safety — we are at least assured it has undergone rigorous testing and regular maintenance checks, with no expense spared for new parts and necessary upgrades.

But passengers in this country have no such reassurances when they step on board local planes.

Crippling international sanctions that banned the import of new aeroplanes and much-needed aircraft parts have left Iran with a dysfunctional air travel industry where disaster has practically been waiting to strike. And this week — and not for the first time — it did.

All 66 passengers and crew on Iranian Aseman Airlines flight 3704 were killed when the ageing plane crashed, likely due to bad weather, on Sunday.

The wreckage of the twin-engined turboprop ATR 72, which had taken off from Tehran, was found on Tuesday night in a mountainous area close to its destination city of Yasuj.

The doomed plane was 24 years old — quite young, compared to the rest of Aseman’s fleet — and had been grounded for six years before it returned to the skies just three months ago.

Iran’s President Hassan Rouhani has ordered an investigation into the crash.

But while he awaits his transport minister’s findings on the specific cause, the tragedy has brought the spotlight back on Iran’s struggling airlines, which have had no choice but to fly with very little.

Tehran has blamed sanctions for preventing its airlines from buying new planes and spare parts from the West, and therefore jeopardising the safety of its passengers.

Most of that blame has been put on the United States, which has to give permission to jet giants Boeing and Airbus to sell aircraft to countries such as Iran. (France-based Airbus is not an American company, but a significant volume of its aircraft components come from the US.)

During sanctions against Iran, accessing spare parts was so difficult for airlines, Aseman was forced to ground planes.

Planes that were kept in service were done so using parts that had been bought on the black market or cannibalised from other aircraft.

Relief appeared to come in 2015, when world powers agreed to lift the tough sanctions — including those on aviation purchases — in exchange for Tehran curbing its nuclear program.

Following this, the US gave Boeing and Airbus the green light to sell tens of billions of dollars of aircraft to Iran.

Aseman itself bought 30 Boeing 737 MAX jets for $3.8 billion in June, with an option to buy 30 more, according to AFP.

But fresh question marks are hanging over Iran’s new-found access to aircraft and precious parts beyond its borders.

Just a week before the crash of flight 3704, the US, Great Britain and France drafted a resolution to renew sanctions again Iran, accusing Tehran of failing to stop the supply of ballistic weapons to Yemen’s Houthi rebel group, which Iran disputed.

Meanwhile US President Donald Trump’s administration has for months threatened to reimpose sanctions against Iran — including a ban on aviation exports — citing violations of the 2015 agreement.

“Since the signing of the nuclear agreement, the Iranian regime’s support of dangerous militias and terror groups has markedly increased,” the US ambassador to the UN, Nikki Haley, wrote in the New York Times just days before the plane crash.

“Its missiles and advanced weapons are turning up in war zones all across the Middle East.”

Aseman Airlines is not currently under sanctions but it was black-listed by the European Commission in December 2016 for failing to meet international safety standards.

The crash of flight 3704 is the latest in a long list of tragedies to strike Iran’s struggling air travel industry.

Among them was a 2014 Sepahan Airlines crash in Tehran that killed 40 people.

A Boeing 727 crashed in northwest Iran in 2011, killing 78 people.

In 2009, 168 people died when a Tehran-based Caspian Airlines plane crashed on its way to Armenia.

And 2003, a troop carrier crashed in southeast Iran, killing all 276 soldiers and crew on board.