There are certain obligations both on the employee and employer. The employee should make every effort to contact the employer to explain their predicament and to indicate as best they can when they are likely to be back. In these circumstances contact can be made by phone, email or text message. For small organisations absence of key employees can have a devastating effect especially if the absence is prolonged and unplanned stopping the employer from taking contingency action to cover the absence.
If the employee fails to make any sort of contact the employer can think about treating this as an unauthorised absence An employer can always decide to exercise its discretion and take a pragmatic approach and pay employees for some or all of the days they cannot make it into work where their absence is beyond their control. However, you must ensure all employees are treated in the same manner so if in December there is snow and people can’t get to work you must adopt the same approach, A sensible way to approach this it to ask the employee to take additional holiday or take the extra days as unpaid leave or if that is not possible put together a practical solution to allow the employee to make up the extra time by say unpaid overtime over a period i.e. if they have been delayed by 5 days and a normal working day is 8 hours then they work 1 extra unpaid hour for the next 40 days messy but fair.
These events regrettably seem to becoming more common there was a similar problem in Tunisia earlier this year and there are always air traffic or weather issues which may unavoidably delay employees return
Employers should review their holiday policies and make sure they are updated to cover these contingencies and to communicate to all employees what is expected in these circumstances and how the employees should act. Existing contracts should updated every 3 years anyway and this should be included in the next update.