Alton Towers owner Merlin Entertainments said it had "learned every lesson" from last year's Smiler rollercoaster crash as it revealed that visitor numbers were still being affected.
The group said the Alton Towers theme park had seen trading start to recover over the summer, but admitted that visitor numbers were still "some way" below levels before last year's collision, in which five people seriously injured, including two teenagers who each lost a leg.
Merlin was fined £5 million earlier this week after admitting health and safety breaches.
Judge Michael Chambers QC, passing sentence at Stafford Crown Court, called the accident a "catastrophic failure" by the company involving basic health and safety measures.
In Merlin's latest trading update, chief executive Nick Varney said: "We have learned every lesson from what happened last year and made a number of technical and procedural improvements to make sure that an accident like this cannot happen again."
Merlin said its resort theme parks - which also include Thorpe Park and Chessington World Of Adventures - was now seeing year-on-year growth in like-for-like revenues, up 3% in the nine months to September 17, after signs of a recovery at Alton Towers.
But the group warned that recent terrorist attacks across Europe have hit demand for its London attractions and said there had been no boost so far from the Brexit-hit pound on tourism trade.
Like-for-like revenues over the 38-week period fell 0.4% at its so-called midway attractions, such as Madame Tussauds and The Dungeons, although it said its Eye-Popping Days Out marketing campaign helped halt the decline in August.
Merlin said underlying earnings margins would remain under pressure throughout 2017, but added that it was focusing on cutting costs and targeting its marketing in strategic markets.
Overall it posted a 1.3% rise in like-for-like revenues across its attractions.
Mr Varney said: "London in particular continues to suppress overall trading performance as we are yet to see any significant benefit from the depreciation of sterling."