The men are being questioned over an alleged plot to fund terrorist activities.
This follows the arrest last week of another British Airways employee from Newcastle on similar charges.
From the Daily Mail:
A Heathrow Airport worker is in police custody today after a series of raids into an alleged terrorist fund-raising plot.
The man is the second British Airways worker held after three men were arrested in dawn raids this morning, taking to four the number in custody.
It follows the arrest on Thursday of a 30-year-old British Airways employee in Newcastle.
The three men, aged 31, 32 and 43, were seized by police at 5am today in Slough.
The men are now being questioned about a plot to fund a terrorist attack.
Police refused to clarify what positions the two BA employees had within the airline. Sources said the latest arrests were 'significant'.