With the Boeing 787 set to return to revenue service, airlines worldwide are developing plans to get the fleet back in the air as soon as possible. Ethiopian Airlines said it could be flying by April 27, but for most carriers, the process is frustrating. It seems clear that many will not be flying until June.

Boeing delivered 50 aircraft before the Jan. 16 grounding. All Nippon Airways (ANA) is by far the largest operator with 17, followed by Japan Airlines (JAL) with seven. United Airlines and Air India both have six; Qatar Airways received five. Ethiopian took delivery of four, LAN had three and LOT Polish Airlines two. Complicating the repair work is the fact that many of the aircraft are not grounded at their home bases. One of the LOT aircraft has been stranded at Chicago's O'Hare International Airport since it touched down there following its inaugural service. One of the ANA aircraft has been parked in Frankfurt, while some are at Tokyo-Haneda and other airports throughout Japan. None of the six United aircraft were in Chicago. One of the seven JAL aircraft was still in Boston. Some those 787s will be repositioned before the battery modifications are undertaken.

Both All Nippon Airways and Japan Airlines started battery modifications on their aircraft on April 22. The two rivals account for the majority of the 787s delivered so far, and they have been hardest hit by the aircraft's grounding due to problems with its lithium-ion batteries.

An ANA spokesman tells Aviation Week that five support teams from Boeing are each working on one of the carrier's aircraft, and the modifications will take about a week per plane. All 17 of ANA's 787s are scheduled to be finished by the end of May. The spokesman emphasizes that ANA still needs a revised Technical Circular Directive to be issued by the Japan Civil Aviation Bureau (JCAB) before it can begin test flights of its 787s.

Boeing has already conducted flight testing for the battery fix, and on April 19 the FAA granted approval for the modification design. A formal directive allowing 787s to return to flight with the modification is expected this week. The JCAB will likely follow with its own directive.

Although there were reports circulating that ANA plans to conduct 100-200 test flights on the 787s within Japan, an airline spokesman says “nothing is decided yet and we will continue to communicate closely with the Japanese agency and Boeing [as to] how many flights we fly before the 787 returns to service.”

ANA had already announced in February that it would extend the cancelation of 787 flights to May 31, to provide some certainty to its scheduling. The spokesman says this plan remains in effect, which signals that the 787s will return to scheduled service at the beginning of June.

This would allow 787s to resume flying on routes where they have been temporarily replaced with other aircraft. Frequencies have had to be reduced, and some routes cut altogether to accommodate the groundings.

Some of the international routes that have been suspended due to the groundings may take longer to be reintroduced, says the ANA spokesman. “It is not decided yet, but it seems we need more time to resume services to both Seattle and San Jose, [Calif.],” he says.

When ANA first announced that the 787 cancellations would extend to May 31, an airline representative told Aviation Week that if the aircraft were cleared before then, the carrier might consider using some for special “relief flights,” to boost the domestic schedule where necessary. The spokesman confirms there is still a possibility that such flights may occur during May.

Japan Airlines was operating seven 787s on international routes before the grounding. It has arranged for alternate aircraft on these routes through the end of May, and has also had to cut some frequencies. The carrier says it will make a decision about when its 787s will return to service after JCAB has issued its clearance.

A JAL spokesman says no decision has been made on when test flights will begin. The airline had to postpone the start of a new route to Helsinki due to the 787 problems. There is no word on a revised launch date.

United Airlines, with a fleet of six 787s, the only North American operator of the type so far, says it is selling tickets for domestic flights on 787s from May 31 onward. The airline also plans to launch its new Denver-Tokyo Narita route on June 10 using the aircraft. United cautions that this will depend on completion of the modifications before that date. On the other hand, United is prepared to make “additional schedule changes, and possibly insert more 787s [back in the schedule] earlier,” as it gains more visibility on how the modification work progresses.

A spokesman for LAN says the carrier is working with the authorities and Boeing on implementing the modifications on its three aircraft, but did not reveal any dates or destinations.

Air India has plans to restart 787 flights toward mid-May, initially on domestic routes. The airline is looking at adding long-haul services by the end of May, initially from New Delhi to Frankfurt and Paris. Air India flew the aircraft to Bangalore, Calcutta and Chennai before the grounding. Of the airline's six 787s, it plans to work on two aircraft at a time once the new batteries have been delivered. The work is expected to take about one week per aircraft.

Qatar Airways plans to resume scheduled services on May 5, initially on the Doha-Dubai route. The carrier leaves open when the 787 will be redeployed on long-haul routes, although CEO Akbar Al Baker has made clear he wants this to happen as soon as possible.

LOT will send its two 787s to Ethiopian Airlines' MRO facilities in Addis Ababa for the modifications. LOT CEO Sebastian Mikosz says it will take the airline around 6-8 weeks to get the aircraft back in the air. He has voiced his frustration via several media outlets, saying: “That's not how I imagined being treated.” LOT is also working on training its pilots for the 787 and the airline should be in a position to deploy the new aircraft by the end of June. Ethiopian has taken delivery of four 787s.

In addition to the airlines whose fleets have been grounded, there are a number of carriers that are anxiously awaiting delivery of their first 787s because they are the linchpins of new routes that some airlines have planned.

Norwegian should have already received its first long-haul aircraft in order to initiate services to New York at the end of May. Instead, the airline has been forced to wet-lease two Airbus A340-300s to serve as interim capacity providers.

U.K. airlines—including charter company Thomson Airways and major carrier British Airways—are waiting to hear from Boeing about the status of their deliveries.