Drivers at Hull Trains are set to strike for eight weeks over the sacking of a colleague.
Aslef said a driver was unfairly dismissed after raising a safety issue at a meeting, a claim the company denies.
Members of Aslef will walk out on March 31 to May 24.
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Mick Whelan, Aslef’s general secretary, said: “The company’s failure to act responsibly has an impact – and enormous implications – not just for rail workers and passengers at the company but for staff and passengers right across the wider rail industry.
“This is a moral issue because we have a culture on the railway designed to keep everyone safe.
“Anyone who works on the railway should be able to report a safety concern without fearing they will be penalised, punished, or lose their livelihood. The company has behaved deplorably.”
A spokesperson for Hull Trains said: “We’re disappointed to receive notice of further strike action from Aslef.
“Safety will always remain our number one priority.
“We are currently reviewing the impact of these latest proposed strike action dates and any changes to services will be communicated in due course.”
