American Airlines has joined Southwest in canceling flights of the troubled 737 MAX through the busy northern summer peak period but believes it will be recertified sooner than August. Southwest had already announced it would cancel MAX flights until August 5 and American joined it on Sunday by canceling 115 flights a day through to August 19.  This represents about 1.5 percent of American’s flying. However, American chief executive Doug Parker said consultations with the US Federal Aviation Administration and Boeing meant the airline remained “highly confident” the MAX would be recertified before this time. READ: Data suggest Ethiopian Airlines' sensor damaged on take-off He said the move to extend cancellations through summer was so the airline could plan more reliably for the peak season and provide confidence to customers and staff about their travel plans. “Once the MAX is recertified, we anticipate bringing our MAX aircraft back online as spares to supplement our operation as needed during the summer,’’ Parker said. “We remain confident that the impending software updates, along with the new training elements Boeing is developing for the MAX, will lead to recertification of the aircraft soon. “We have been in continuous contact with the FAA, Department of Transportation (DOT), National Transportation Safety Board (NTSB), other regulatory authorities and are pleased with the progress so far.'' Southwest, which has the biggest number of MAX aircraft,  said its decision meant it would cancel 160 MAX-related flights per day. Southwest president Tom Nealon said the airline's cancelations were also designed to boost reliability. "While the timing for the return to service of the MAX remains unclear, what is very clear is our commitment to operate a reliable schedule and provide the famous customer service you expect from us,'' he said in a letter to customers. READ our 737 Max coverage. Airline staff are contacting customers on affected flights and they have been told they can receive a refund if they choose not to rebook. The grounding of the planes after two crashes in less than five months has affected airlines of all sizes worldwide. Pacific carrier Fiji Airways announced last week it had been forced to wet lease a Boeing 737-800 from Miami Air to cover some its schedules after its two MAX 8 aircraft were grounded. The chartered US-based charter company Miami Air aircraft will operate some flights on behalf of Fiji Airways between Nadi and Auckland, Apia, Christchurch and Brisbane with 166 economy seats. The aircraft operates using Miami Air's cabin crew and pilots with a Fiji Airways Purser or senior flight attendant onboard to oversee the cabin experience. Fiji said it had made the decision to lease the plane in the peak period to limit any disruptions to guests’ travel plans. "While the airline recognizes that the onboard experience and facilities will differ from its usual offering, it will do everything possible to ensure that guests continue to enjoy a comfortable experience,'' it said. "Fiji Airways will contact Business Class guests booked on flights which will now be operated by the leased aircraft to provide travel options."