Indian packed-service carrier Vistara will operate its last flight on Monday, after nine years in existence.

A joint enterprise between Singapore Airlines and the Tata Sons, Vistara will merge with Tata-owned Air India to form a single entity with an expanded network and broader fleet.

This means that all Vistara operations will be transferred to and managed by Air India, including helpdesk kiosks and ticketing offices. The procedure of migrating passengers with existing Vistara bookings and loyalty programmes to Air India has been under way over the history few months.

“As part of the combination procedure, meals, service ware and other soft elements have been upgraded and incorporates aspects of both Vistara and Air India,” an Air India spokesperson said in an email response.

Amid concerns that the combination could impact service standards, the Tatas have assured that Vistara’s in-flight encounter will remain unchanged.

Known for its high ratings in food, service, and cabin standard, Vistara has built a faithful customer base and the selection to retire the Vistara brand has been criticised by fans, branding experts, and aviation analysts.

The combining was effectively done to tidy up Vistara’s books and wipe out its losses, said Mark Martin, an aviation analyst.

Air India has essentially been “suckered into taking a setback-making airline” in a desperate shift, he added.

“Mergers are meant to make airlines powerful. Never to wipe out losses or cover them.”

To be sure, both Air India and Vistara’s annual losses have reduced by more than half over the history year, and other operating metrics have improved too. But the combination procedure so far has been turbulent.

The exercise has been riddled with problems – from pilot shortages that have led to massive flight cancellations, to Vistara crew going on mass ill leave over plans to align their salary structures with Air India.

There have also been repeated complaints about impoverished service standards on Air India, including viral videos of broken seats and non-functioning inflight entertainment systems.

The Tatas have announced a $400m (£308m) programme to upgrade and retrofit the interiors of its older aircraft and also a brand-recent livery. They’ve also placed orders for hundreds of recent Airbus and Boeing planes worth billions of dollars to augment their offering.

But this “turnaround” is still incomplete and riddled with problems, according to Mr Martin. A combination only complicates matters.

Experts declare that the combination strikes a dissonant chord from a branding perspective too.

Harish Bijoor, a brand way specialist, told the BBC he was feeling “emotional” that a superior product offering like Vistara which had developed a “gold standard for Indian aviation” was ceasing operations.

“It is a large setback for the industry,” said Mr Bijoor, adding it will be a monumental job for the mother brand Air India to simply “copy, paste and exceed” the high standards set by Vistara, given that it’s a much smaller airline that’s being gobbled up by a much larger one.

Mr Bijoor suggests a better way would have been to operate Air India separately for five years, focusing on improving service standards, while maintaining Vistara as a distinct brand with Air India prefixed to it.

“This would have given Air India the period and chance to rectify the mother brand and bring it up to the Vistara level, while maintaining its uniqueness,” he adds.

Beyond branding, the merged entity will face a slew of operational challenges.

“Communication will be a major test in the early days, with customers arriving at the airport expecting Vistara flights, only to discover Air India branding,” says Ajay Awtaney, editor of Live From A Lounge, an aviation portal. “Air India will require to maintain obvious communication for weeks.”

Another key test, he notes, is cultural: Vistara’s agile employees may battle to adjust to Air India’s complicated bureaucracy and systems.

But the biggest job for the merged carrier would be offering customers a uniform flying encounter.

These are “two airlines with very different service formats are being integrated into one airline. It is going to be a hotchpotch of service formats, cabin formats, branding, and customer encounter. It will involve learning and unlearning, and such a procedure has rarely worked with airlines and is seldom effective,” said Mr Martin.

Still, many depend Vistara had to leave – now or some years later.

A legacy brand like Air India, with powerful global recognition and ‘India’ imprinted in its identity, wouldn’t have allowed a smaller, more additional expense subsidiary to overshadow its revival procedure.

Financially too, it makes little sense for the Tatas to have two setback-making entities compete with one another.

The combined strength of Vistara and Air India could also place the Tatas in a much better position to compete with economy chief Indigo.

The unified Air India throng (including Air India Express, which completed its combination with the former Air Asia India in October) “will be bigger and better with a fleet size of nearly 300 aircraft, an expanded network and a stronger workforce”, an Air India spokesperson said.

“Getting done with the combination means that Air India grows overnight, and the two teams commence cooperating instead of competing. There will never be one correct day to merge. Somewhere, a line had to be drawn,” said Mr Awtaney.

But for many Vistara loyalists, its demise leaves a void in India’s skies for a additional expense, packed-service carrier – marking the third such gap after the collapse of Kingfisher Airlines and Jet Airways.

It’s still too early to declare if Air India, which often ranks at the bottom of airline surveys, can successfully fill that void.