(Bloomberg) -- Deutsche Lufthansa AG may face unlimitedliability for payments to families of victims of the Germanwingsjet crashed by its suicidal co-pilot, according to lawyers.

“The liability for the victims would be uncapped,” said GeorgeLeloudas, a lecturer at Swansea University College of Law whospecializes in aviation law. “From the perspective of the airlineit’s difficult. There are no real defenses that you can use. It isirrational. That is why you buy insurance.”

The crash on Tuesday, killing all 150 passengers and crew,mystified investigators because the plane flew in normal daylightconditions and had undergone routine checks. French investigatorsThursday said Andreas Lubitz, the 27-year-old co-pilot of theplane, allegedly locked the pilot out of the cockpit andintentionally flew the aircraft into a mountainside in the FrenchAlps.

Investigators said Friday they found a torn-up doctor’s note inLubitz’s home that certified he was unfit for work on the day ofthe crash. Authorities believe Lubitz, who was in treatment, hidhis medical condition from his employer, according to a statementfrom Dusseldorf prosecutors, who are leading the investigation inGermany.

Because the flight from Barcelona to Dusseldorf wasinternational, it’s governed by the 1999 international accord knownas the Montreal Convention, lawyers said. Under that agreement,crash victims’ families are automatically entitled to 100,000special drawing rights, the equivalent of $139,000.

“That does not limit a person’s recovery,” Kevin P. Durkin, anair crash liability attorney with Chicago’s Clifford Law Offices,said in a phone interview on Thursday.

Should a claimant seek more, the burden is on Germanwings toprove that some entity other than it was the only cause of theoccurrence, he said.

$350 Million

“We believe there is at least $1 billion of insurance cover onoffer for Germanwings,” James Healy-Pratt, an aviation lawyer atStewarts Law LLP in London, said in a phone interview. “We haveactually assessed the likely compensation total to be around $350million.”

Germanwings will be insured “even if it is proved thatintentional pilot conduct, suicide, was the cause of this tragedy,”he said.

The “insurance remains valid unless there is cast iron evidencethat senior management at Germanwings actively colluded in thealleged criminal activities of the co-pilot.”

French prosecutors have already opened a criminal investigationinto the circumstances of the crash.

Medical Tests

Lufthansa Chief Executive Officer Carsten Spohr said theco-pilot had passed all medical tests and checks, and had startedtraining in 2008, both in Bremen in northern Germany and inPhoenix, Arizona. All cockpit personnel undergo thoroughexamination, said Spohr at a press conference Thursday, calling theincident a “tragic, isolated case.”

The company didn’t immediately respond to questions about itspotential liability following the crash.

Lufthansa, which had operated the aircraft before it was handedover to Germanwings at the start of 2014, said the cockpit hadfortified doors with video surveillance to prevent unauthorizedentry, a measure that became mandatory after the 9/11 terrorattacks in the U.S. While pilots have a security code that letsthem open the door from the outside, the person remaining in thecockpit can still deny access.

While the amount of liability payments is not limited, thequestion what counts as damages is governed by national rules, saidElmar Giemulla, a lawyer and professor of aviation law at Berlin’sTechnical University.

Main Breadwinner

Under German law, this includes payouts for psychologicaltreatments and burial costs. If a victim was the breadwinner for asurviving family, the airline has to make up any cost of livingpayments for dependents, like alimony payments for children untilthey reach the age of 27. He estimates this is around 6,000 euros ayear per child.

“These are not big sums, nothing threatening for the airline,”said Giemulla.

“And of course, this is insured anyway,” he said. “Normally,these cases do not go to court, the airlines are willing to pay anddo pay.”

--With assistance from Sarah Jones, Heather Smith and AndreaGerlin in London, Karin Matussek in Berlin, Richard Weiss inFrankfurt and Oliver Suess in Munich.

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