New Delhi: All Boeing 737 Max 8 aircraft being operated by Indian airlines have been grounded and around 35 flights of SpiceJet would be cancelled on Thursday consequently, Civil Aviation Secretary P S Kharola said Wednesday. He said Thursday will be a "challenging" day as "out of 520 odd flights that SpiceJet flies every day, about 30-35 flights will have to be cancelled".

As the Ethiopian Airlines' 737 Max 8 crashed near Addis Ababa killing all 157 people onboard on Sunday, Indian aviation watchdog Directorate General of Civil Aviation (DGCA) Tuesday night announced that the Boeing 737 Max 8 aircraft would be "immediately" grounded.

"Tomorrow is going to be a real challenging day because today the ban has come into effect only from the second half of the day... SpiceJet has assured us that they have taken up multiple plans. They have increased the utilisation of existing aircraft, so that the cancellations get limited," Kharola said.

"As of now, all aircraft of B737 Max have been grounded. The last flight (aircraft) to be grounded was today around 2.30 pm. The deadline was 4 pm and before that all aircraft have been grounded," he said.

SpiceJet has been most affected by the grounding of 737 Max 8 aircraft as it has 12 of them in its fleet.

Jet Airways has not been affected as its five 737 Max 8 aircraft have already been grounded - even before the grounding decision of the government -- due to non-payment of dues to lessors.

On Wednesday morning, the DGCA issued a statement stating no Boeing 737 Max 8 aircraft would be allowed to fly in Indian airspace from 4 pm.

"We had a discussion with airlines as to how they would plan to overcome the situation. The airlines have assured that the grounding of 12 aircraft would not significantly impact the passengers and they would draw up a very elaborate plan," the secretary said.

"Today, SpiceJet has just cancelled 14 flights... They have been able to accommodate the passengers affected by cancellation of 14 flights within their own system," he added.

Kharola emphasised that the SpiceJet has been told that cancellations of flights should happen on those sectors that have multiple flights. He added that SpiceJet has assured that if the airport has only its flights, it will not go "unserviced" due to aircraft ban.

He said added that SpiceJet would be setting up special cell to deal with passenger complaints and ensure that the passengers are informed well in time about cancellations or any other adjustments.

He added that the ministry has requested SpiceJet that in case it is not able to adjust or accommodate, other airlines should come forward and they should carry these passengers based on their existing agreements with SpiceJet.

Operators have also agreed not to indulge in "predatory pricing", the secretary said.

DGCA chief B S Bhullar said that lifting the ban on the 737 Max 8 aircraft will be based on inputs from various agencies and it will not happen soon.

He added that other airlines - apart from SpiceJet - have been requested to keep fares at a reasonable level and the DGCA will monitor fare levels regularly.

In a statement Wednesday evening, SpiceJet said, "SpiceJet is rationalizing & optimizing the use of its Boeing 737 NG and Bombardier Q400 aircraft to address the current situation and minimize inconvenience to its passengers."

"We are evaluating options for augmenting capacity in the coming days through a mix of additional flights & aircraft inductions. We are sure that our operations will be normal very soon," it said.

The airline said that a majority of passengers affected as a result of these cancellations have been accommodated on alternate flights.

The budget carrier said it is offering passengers the option of "a full refund, changing the flight/date of travel, or even change of destination (to nearest alternate airport); all this without any cancellation charges or any fare difference".

While European Union and most countries across the world have decided to ban the use of Boeing 737 Max 8 aircraft, the US has refused to do it as yet.

Federal Aviation Administration (FAA), which regulates aviation industry in the US, said in a tweet Wednesday that it "continues to review extensively all available data and aggregate safety performance from operators and pilots of the Boeing 737 MAX".

"Thus far, our review shows no systematic performance issues and provides no basis to order grounding the aircraft. Nor have other civil aviation authorities provided data to us that would warrant action," it said, adding it will take immediate and appropriate action if any issues affecting the continued airworthiness of the aircraft are identified.