Lufthansa Group has reported an operating profit down 3.2% at €983 million ($1.15 billion) for the second quarter, citing a "stressful period" for subsidiary Eurowings.
The budget unit's earnings "developed negatively", says the group, while praising the performance of its network carriers.
Group revenue rose 0.4% to €9.3 billion in the second quarter.
Lufthansa says first-half earnings were only "marginally below the record result" of the previous year, "largely driven" by positive development of the group's network airlines, including Lufthansa mainline, Swiss and Austrian Ailines.
The network carriers boosted their operating profit 4.9% to €836 million in the second quarter, though revenue was down 3.7% at €5.94 billion.
Lufthansa describes the first half of the year as "very busy and stressful" for Eurowings. The subsidiary's second-quarter operating profit fell 91% to €5 million.
Its parent notes "increasing service irregularities" in the form of flight delays and cancellations which necessitated "significant modifications" to Eurowings' summer schedule.
Lufthansa argues that particular causes of the irregularities were the European Commission decision not to approve the group's acquisition of Niki and the termination of a partnership with the Austrian carrier's successor Laudamotion.
Another factor Lufthansa cites is a delay in incorporating ex-Air Berlin aircraft into the fleet. Lufthansa links this delay to the German aviation regulator's certification process for commercial aircraft.
Eurowings' operations were also adversely affected by external factors such as air traffic controller strikes, "manpower shortages" within European ATC and weather-related flight cancellations, says Lufthansa.
The Star Alliance group says its first-half performance was "overall in line" with its expectations for the full year, but expects its adjusted operating profit for 2018 to be "slightly below" the level achieved last year.