Lufthansa has denied claims that it withheld information about the health of Andreas Lubitz. The copilot of the subsidiary Germanwings is believed to have deliberately crashed a plane into the French Alps.
The German airline said on Monday that it was not required to inform German aviation authorities about Lubitz's past depression as he qualified as a pilot before stricter reporting rules came into effect in Germany in April 2013.
Lufthansa said that a provision in the new regulation, safeguarded certain pre-existing fit-to-fly certificates and medical certificates issued by specialized aviation doctors.
Aeromedical centers or aviation doctors could therefore issue extensions to such medical certificates even after the new rules came into effect, the airline said.
"A general and separate duty to refer to the Luftfahrtbundesamt (LBA) did not therefore arise as a result of the change in the legal position," Lufthansa said.
Under European regulations, pilots with psychiatric conditions should be referred to the licensing authority by aeromedical examiners, who may then decide to restrict the pilot's licence.
The LBA, the relevant German authority, said on Sunday it had "no information at all" before the crash about Lubitz's depression.
The question of what and if Lufthansa knew about any of Lubitz's psychiatric problems may become a factor in its liability in the crash.
Last Tuesday, Lufthansa said it had set aside $300 million (279 million euros) to cover financial compensation for victims' families and the cost of the aircraft itself, which belonged to the budget airline carrier Germanwings.
Lufthansa has already offered victims' families up to 50,000 euros in immediate financial assistance.
Lubitz, who is thought to have deliberately killed all 150 passengers and cabin crew on board the the A320 airbus on March 24, broke off pilot training for several months in 2009.
On resuming his pilot training, he told Lufthansa pilot instructors in an email that he had overcome a period of severe depression. He was first certified to fly commercial planes in 2012.
German prosecutors said last week that Lubitz had also received psychotherapy treatment for suicidal tendencies before he became a pilot.
"Several years ago before obtaining his pilot's license, the co-pilot was in a long period of psychotherapeutic treatment with noticeable suicidal tendencies," said the prosecutor's office in Düsseldorf, where Lubitz had lived.
ksb/rc (AFP, Reuters, dpa)