Two German pilots on a world tour took Calcutta airport for a pit stop where they could land, park and walk out without any formalities and, shockingly, did so unnoticed until moments before their return journey two days later.

Marc Aurel Lehmann and Carl Heinz Maxwitat, both in their late 60s, landed their two-seater DA 40 aircraft at Netaji Subhas Chandra Bose International Airport on Monday and casually walked out after parking it on hangar No. 9, close to where Air India keeps its aircraft.

The veteran pilots didn’t bother going through immigration and customs clearance, and none of the airport personnel who might have seen the duo walking out bothered to tell them that they should.

The security breach was discovered only on Wednesday, when Lehmann and Maxwitat showed up at the immigration counter before they were to take off for Phuket, Thailand.

“They admitted to making a mistake and apologised. Their documents were checked and because everything was in order, they were allowed to leave,” said Basab Talukdar, the deputy commissioner of security control and foreigners’ regional registration officer.

Asked whether such blatant disregard for security regulations did not merit stringent punishment, the official said they were “reprimanded” for the act.

The Germans told immigration officials that they were “extremely tired” and needed rest, which is why they “hurried off to a hotel”.

This is the second such security breach at the airport this year. In January, three passengers of a flight from Yangon walked out of the airport without going through immigration and customs.

The passengers were, however, not entirely to blame. The driver of the Air India bus they boarded after deplaning dropped them at the domestic terminal instead of the international one.

Calcutta airport’s brush with Lehmann and Maxwitat did not end with the duo taking off after a mere apology. After travelling 180 nautical miles south of Calcutta, Air Traffic Control lost touch with the pilots.

“We contacted Bangkok later and were informed that the aircraft was 50 nautical miles north of Phuket,” an official said.

The Germans had started their world tour in Berlin and halted at two other Indian cities — Ahmedabad and Nagpur — before coming to Calcutta for refuelling and two days of rest. They stayed in a hotel off EM Bypass.

Airport sources said it was the responsibility of the handling agent —usually an airline— to guide foreign pilots through the necessary formalities. Lehmann and Maxwitat did not have a handling agent and drew up their travel plans on their own.

“The security breach will be brought to the notice of the directorate-general of civil aviation,” a senior official of the Airports Authority of India said.