In a further setback, the RMT union, which represents train crew and other ScotRail workers, has rejected the offer and threatened a strike ballot.
The train operator said it would not reinstate the timetable until the Aslef dispute was resolved, which is not expected until mid-July because union officials want the proposed deal put to a vote by members.
Aslef’s executive committee is due to decide whether to go ahead with the referendum next Wednesday, which would take three weeks to stage. ScotRail said it would then need ten days after any settlement was reached to restore nearly 700 suspended daily services, or one third of the timetable.
It is not known whether drivers will start resuming working overtime now that an offer has been recommended for approval, which could see some trains restored sooner.
The 5 per cent offer, which would be backdated to April, was made during fresh talks following Aslef rejecting a 4.2 per cent offer last week, and a 2.2 per cent offer before that.
It would increase drivers’ basic pay by more than £2,600 to £55,264.
Rejection of the original offer led to most drivers no longer volunteering to work overtime, on which services depend, especially on Sundays.
That led to hundreds of short-notice cancellations a day, prompting ScotRail to introduce temporary reduced timetables from May 23 in an attempt to provide certainty to passengers, which included cutting Sunday services by half and last trains leaving hours earlier than normal.
ScotRail said the latest offer was a combination of the Transport Scotland-funded public sector pay limit of 2.2 per cent, under which the newly-nationalised firm operates, and a further 2.8 per cent “which recognises and rewards the flexibility of rostering arrangements”, which it would fund by revenue growth.
The package also included drivers sharing revenue when targets are exceeded, worth £2,535, higher pay for working on Sundays and rest days, and improvements to maternity and adoption leave.
The RMT said it would accept the pay offer if a clause was removed that required staff to use unspecified new technology in the future.
Scotland organiser Mick Hogg said: “If the company does not see sense, I will recommend we proceed to a ballot for industrial action.”
In a separate dispute, the RMT has called Britain-wide rail strikes on June 21, 23 and 25 over pay and jobs at other train operators and Network Rail.
However, they would also have a significant knock-on effect on ScotRail because signallers are due to take part in the walkouts.
Meantime, the improved Aslef offer is likely to encourage other public sector workers to demand similar pay increases.
It stiffened the resolve of the GMB union, which is staging a strike ballot among council workers.
The union said the award showed the “paltry” 2 per cent its members had been offered was “neither credible nor acceptable”.
The Educational Institute of Scotland has also warned teachers are prepared to “vacate classrooms” if a separate pay dispute with Cosla is not resolved.
A ScotRail spokesperson said: “It would take ten days from resolution to reinstate the timetable, but dates are all dependent on the trade unions.”
David Simpson, its service delivery director, said: “We’ve made a really good offer, which recognises the cost-of-living challenges faced by families across the country and delivers good value for the public.
“The feedback we’ve had from many drivers is that they recognise we have made a series of very good offers and we are pleased they will get a say in a referendum.”
Aslef Scottish organiser Kevin Lindsay, said: “We are pleased that today significant progress has been made in our latest round of talks with ScotRail.
“All these proposals, we believe, represent a breakthrough and significant progress and is a recognition of the vital role our members play for society and the economy.
“The full Aslef negotiating team is recommending acceptance of the offer to our members through a referendum, subject to executive committee approval [on June 15].”
A Transport Scotland spokesperson said: “We welcome Aslef’s recognition of the very good offer on the table, an offer which is in part self-funded through increased revenue and roster flexibilities, and also that they will now take this to their members with a recommendation to accept.”