Airbus landed its biggest ever airliner deal yesterday with an agreement to sell 430 planes worth up to $50 billion to US budget airlines investor Bill Franke.

The preliminary deal for A320neo narrowbody jets was signed at the Dubai Airshow and offers a major boost to Airbus, which has lagged archrival Boeing in deals this year.

It also ensures veteran sales chief John Leahy retires on a high in the coming months.

But Boeing immediately hit back with a provisional agreement to sell 175 planes to budget airline flydubai. Including options to buy a further 50 planes, that deal could be worth $27 billion at list prices.

The deal between Airbus  and Franke’s Indigo Partners is the industry’s largest ever by number of aircraft

The deal between Airbus and Franke’s Indigo Partners is the industry’s largest ever by number of aircraft.

Indigo plans to supply the A320neo narrowbody jets to four airlines in which it has stakes: Frontier Airlines, Mexico’s Volaris, Chilean carrier JetSmart and Hungary’s Wizz Air.

Airbus said it expected to finalise the transaction with the 80-year-old Franke in the coming weeks. Its shares were up 2.5 per cent to €85.59 at around midday.

The agreement, along with flydubai’s deal for Boeing’s 737 MAX narrowbody jets, underscores how budget carriers are rewriting the industry rule book by combining bargain fares with optional services and upgrades for which passengers pay extra.

According to some delegates at the air show, the deals also suggest airlines are taking advantage of a recent slowdown in demand for new jets to negotiate competitive prices. The Franke deal marks a dramatic swan song for Airbus sales chief Leahy, who is due to retire in the coming months after holding the job since 1994.

The 67-year-old has overseen the sale of jets worth $1.7 trillion at list prices and helped engineer a rise in Airbus’s market share to a par with Boeing from just 18 per cent.