By Will Smale
BBC News business reporter
The unofficial strike by British Airways staff at Heathrow Airport has once more thrust the state of industrial relations at the airline into the media spotlight.
This is the second summer that BA passengers have seen disruption
The current walkout is an unofficial action in sympathy with workers who were dismissed at another company, BA's food supplier Gate Gourmet.
And BA argues that the current walkout is therefore out of its control.
However, this is the third summer in succession that workers at the UK's flag carrier airline has carried out industrial action.
Last summer staff voted to strike over pay before agreement was reached with BA managers, and some workers stayed home in protest at low staffing levels.
And in 2003 ground staff walked out in protest over a new check-in timekeeping system.
Two summers in a row might be coincidence, but three is surely profligate.
What could be the reason for possible simmering industrial relations strife at BA, and why are some of its staff currently striking when the matter has nothing directly to do with the airline?
The current dispute started when Gate Gourmet, which is BA's sole provider of in-flight meals, sacked 350 members of its staff at Heathrow in a dispute over working practices, pay, and the appointment of temporary summer workers.
Owned by US venture capitalist Texas Pacific
Says it needs to reform outdated working practices
Claims to be facing substantial losses
Sacked staff were angry at the appointment of temporary workers
Thought they were going to be replaced by cheaper labour
Many of staff members of TGWU union
Hundreds of BA baggage handlers and other ground staff at the airport quickly went out on strike in sympathy, despite knowing this would cripple the airline's services from Heathrow, cause chaos for passengers, and cost the company an estimated £10m a day.
Such loyalty to staff at another firm can be explained by a number of factors.
Firstly, both sets of workers are members of the same union, the Transport and General Workers Union (TGWU).
While the union itself has had no involvement in organising the sympathy strike - which is illegal under UK labour law - the striking BA staff see the sacked Gate Gourmet workers almost as colleagues.
This impression is strengthened by the fact that up until December 1997, BA used to make all is own in-flight meals itself, so historically the Gate Gourmet workers would have been on the airline's payroll.
Some of the BA ground staff would also inevitably know Gate Gourmet workers personally, as Heathrow pulls in most of its core personnel from the surrounding London suburbs, and the airport's workers are a close-knit community.
The striking BA workers are also inevitably hoping that their actions will put pressure on BA to intervene in the dispute - which is almost certainly the case - and "encourage" Gate Gourmet to find some agreement.
Summer bargaining power
Another key factor in the BA sympathy strike is the time of year - the middle of the peak summer season.
BA check-in desks have been empty since the latest strike
It is no coincidence that the three last industrial disputes at BA all took place around this time of the year.
With millions of people flying abroad for their summer holiday, staff at BA know that their hand is at its strongest.
While a number of commentators claim BA continues to be hampered by 1970s style militancy among a sizeable minority of its staff, the airline itself disagrees.
"Fundamentally I don't think we do [have an industrial relations problem]," said a BA spokeswoman.
"We have a very hardworking and professional workforce, the current situation is very much an exception to that rule."
The TGWU agrees, adding that it was also doing everything it could to resolve the current situation.
"We want everyone back at work and that includes the sacked workers from Gate Gourmet," said a TGWU spokeswoman.
"We are talking to both it and BA, urging them to get an immediate resolution to the problem.
"We do not condone the unofficial action."
Despite the claims of long running union militancy at BA, the TGWU spokeswoman insisted there were "no outstanding issues" between it and the airline.
Yet BA has now been hit by industrial action three summers in succession.
The walkouts have come since the company started a major restructuring plan that resulted in thousands of job losses.
The restructuring has undoubtedly been a financial success for BA, which is today among the world's most profitable carriers.
However, it appears the firm still has work to do to curb staff militancy and secure the full loyalty of all its employees to match its renewed financial success.