ScotRail is so short of train drivers it is trying to persuade retired staff to return to the cab, Scotland on Sunday can reveal.
The union Aslef condemned the “ridiculous” situation, which it said reflected operator Abellio’s failure to recruit and retain enough drivers.
Staff are understood to be leaving ScotRail because it has one of the lowest pay rates among train companies in Britain.
This has come at a time when it needs more drivers for two new fleets of trains and extra services, which are due to increase again in May.
Aslef figures show ScotRail, which has 1,350 drivers, pays them £47,180 a year.
That puts it in 39th place in a pay table of 45 operators.
It compares to £69,207 at top-rated Eurostar and £65,520 at Virgin Trains West Coast. Others paying more than ScotRail include TransPennine Express (£55,000) and ScotRail sister firm Greater Anglia (£50,267).
Train driving has proved to be hugely attractive, with ScotRail being swamped with more than 22,000 applications for 100 jobs during a previous recruitment drive in 2015.
However, Aslef, the main drivers’ union, said the firm had failed to ensure it had sufficient numbers.
Scottish organiser Kevin Lindsay said: “The successive failures of Abellio management to recruit and retain drivers has led to the ridiculous situation of Abellio attempting to bring retired drivers back into the railway.
“These drivers have worked hard and deserve dignity in retirement without being harassed back into the railway.
“We call on the Scottish Government to stop Abellio attempting this poorly thought-out scheme.
“Abellio should concentrate on improving the terms and conditions of existing drivers to encourage them to remain with Abellio. It should be recruiting trainees and help reduce unemployment here in Scotland.”
A spokesperson for the Scottish Government’s Transport Scotland agency, which awarded Abellio the ScotRail franchise, said: “It is for individual operators to ensure they have enough staff to deliver their franchise obligations.
“Our ongoing investment in rail is bringing more quality jobs and recent successful recruitment drives have increased staffing significantly, with the benefits of this starting to be achieved.”
ScotRail confirmed it was approaching retired drivers, but said no one was being “harassed back into the railway”.
It declined to say how old such drivers were, how many it had contacted and what response it had received.
There is no age limit for drivers, although Aslef said they should retire at the state pension age.
The train operator said a recruitment drive launched last summer for frontline staff, including drivers, was continuing and “anyone involved in that process has actively chosen to work with ScotRail”.
A spokesperson added: “The investment we are making to recruit frontline staff is helping us significantly in enhancing the day-to-day running of services for our customers. The recruitment process is inclusive and we are considering all available options.”