Heathrow and Unite union officials are holding talks to avert strike action that will disrupt airport flights on Tuesday.
Monday's strike at Britain's largest airport ended late on Sunday and some airlines, such as British Airways, reintroduced flights.
With a walkout of workers still scheduled for Tuesday, many more flights risked being canceled.
Heathrow had originally canceled 177 flights when the two-day strike action was announced.
A total of 676 flights were scheduled for departure Monday. While 16 were canceled, five were relocated to other London airports.
& # 39; Hope for resolution & # 39;
Talks are being talked to at the Acas Conciliation Council about the salary agreement, which Heathrow says is worth 7.3% over two and a half years.
A spokesman for Heathrow said: "Unite has chosen to postpone its strike action today. The strike action on Tuesday, August 6 is still scheduled to continue.
" We are continuing talks with Unite today and we remain hopeful that we can find a resolution and stop this disruptive and unnecessary threat of strike action.
"We regret that passengers have been disadvantaged by this and encourage them to contact the airline for updated information on the status of their service."
- Heathrow flights canceled when strike personnel strike.
- Heathrow strike action aborted Monday – BA recovers flights
When Monday's strike was suspended, British Airways recovered flights from Heathrow, and Air Canada, Aer Lingus, Etihad Airways, Flybe and TAP Air Portugal.
Virgin Atlantic relocated flights from Heathrow to Gatwick, as did Qatar which also canceled two flights.
Among the airlines canceling flights were Lufthansa and Swiss, which scraped three each.
Lufthansa had booked 365 affected passengers on alternative flights.
Airlines are now waiting to learn about developments from Monday's talks with the union to determine what impact this will have on their schedules for Tuesday.
& # 39; Contact your airline & # 39;  Heathrow's website contains information for travelers on what to do on strike days. Strikes are also scheduled for August 23 and 24.
It advises passengers to contact airlines, both in the days leading up to their flight and before leaving for the airport.
Passengers should check if their flights out of Heathrow are affected or canceled by contacting the airline. The airline will also advise what to do next.
An airline will usually offer reimbursement or alternative flights to the destination (possibly with other airlines) – although the latter may be more difficult for the airlines during the busy summer season.
It is important for passengers to relate to the airline, rather than making their own alternatives and trying to claim the expenses later from the airline or a travel insurance company.
& # 39; Allow more time & # 39;
If an airline is canceled because of airport employees striking over those employed by the airline, it is unlikely that any additional compensation will be paid, as this will be considered "extraordinary circumstances" beyond the airline's control, Civil Aviation Authority.
The CAA added that the airport is not obliged to pay extra compensation directly to passengers, and whether the airport provides its customers (airlines) with compensation is a commercial matter between two parties.
Heathrow said the airport may seem busier as usual as there will be additional staff to replace those on strike.
It also urged passengers, especially frequent flyers, to allow more time to clear security.  "Our advice to all passengers is to be at the Heathrow terminal two hours before scheduled departure for the UK and European flights, and three hours for all other flights, even if you have already stayed before we arrive at the airport and only travel with hand luggage , "so Heathrow.
Unite has around 4000 members involved in the dispute.
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