In the second quarter, passenger capacity was 22% of the same period in 2019, due to government restrictions and quarantine requirements.
It also operated 1,371 cargo-only flights, up from 1,306 in the first quarter.
At the end of the first half to 30 June, the FTSE 100 group had €10.2bn of liquidity after drawing down from previously committed facilities and issuing €1.2bn of senior unsecured bonds and €825mln of convertible bonds, both oversubscribed.
It also secured a new revolving credit facility and British Airways agreed to defer monthly pension deficit contributions for £450mln between October 2020 and September 2021.
Earlier this month, IAG signed sustainability-linked financing for British Airways' remaining fleet deliveries for 2021 worth US$785mln.
Interim operating losses came in at €2bn from €1.9bn last year, with total revenue down 58% to €2.2bn.
"Our focus is on ensuring our operational readiness, so we have the flexibility to capitalise on an environment where there's evidence of widespread pent-up demand when travel restrictions are lifted,” said chief executive Luis Gallego.
"We welcome the recent announcement that fully vaccinated travellers from amber countries in the EU and the US will no longer have to quarantine upon arrival in the UK. We see this as an important first step in fully re-opening the transatlantic travel corridor.”