36 - ATPL - An aircraft at FL 370 in NAT HLA cannot continue in accordance with its clearance and cannot obtain a revised clearance. After establishing a 5 NM parallel same-direction offset, if remaining in the NAT level band, the crew should normally:

Question 36 - Operational Procedures - ATPL - Airline Transport Pilot license

Climb or descend 1 000 ft.

Maintain the assigned level without any further vertical offset.

Descend 300 ft if tracking east and climb 300 ft if tracking west.

Establish a 500 ft vertical offset from normally used flight levels, unless descending below FL 290.