In the first half of the year, the airport lost money even though people were travelling more for business and holidays.
In the first half of the year, the UK's largest airport reported a pre-tax loss of over $300 million.
A shortage of airline ground handling staff is limiting the capacity of the airport.
Since the introduction of a daily passenger cap, punctuality has improved.
The number of passengers who can leave each day over the peak summer months has been reduced.
The cap had worked, according to John Holland- Kaye.
"We've seen a material improvement in performance since it came into place, punctuality has improved, baggage has improved, performance has improved, and that shows that the difficult decisions we took two weeks ago are having the impact so that passengers can travel with confidence this summer," he said.
Thousands of UK travellers have been disrupted recently.
Demand for travel has returned and airports and airlines are struggling to find staff.