Campaigners against a third runway at Heathrow Airport "planted" 2000 black paper planes in Westminster 's Victoria Gardens to highlight the "grim year" residents will face if the decision goes ahead.
Around 70 people joined forces to plant at 10am on the day MP's return to Parliament.
Heathrow Association for the Control of Aircraft Noise (HACAN) led the event and were joined by peaceful protesters from Stop Heathrow Expansion (SHE), Chiswick against Third Runway (CHATR) and Ealing Noise Action Group (ENAG).
They were also accompanied by environmental campaign group Friends of the Earth and other residents living around the airport.
Campaigner Robert Barnstone said: "We want to remind the MP's this year not to make it too grim for those living in West London.
"We were certainly more positive before Christmas than we would have been had they supported the decision, but the positivity is now met with the reality that it will be decided this year ."
This week, a poll of MPs suggested most were in favour of expanding Heathrow Airport rather than Gatwick .
HACAN Chair John Stewart added: "2016 is likely to be the year when the government makes a decision about a new runway.
"It will be a grim year for Heathrow residents if the government decides to go for a third runway at Heathrow.
"Our New Year’s message to the Prime Minister is we will fight to the bitter end to stop a third runway happening.”
The number of planes planted represented the 2000 daily flights taken if the airport is expanded, up from the current figure of 1350.
In opposition, Back Heathrow Campaign Director, Rob Gray said the expansion is an important opportunity and one residents can benefit from.
He told Getwestlondon: "The protesters are entitled to their views but they only speak for a minority of people in the local communities surrounding Heathrow.
"Most residents living near the airport back a new runway which offers a golden opportunity for more jobs, trade, travel and greater prosperity.
"They are supported by the majority of MPs who want to see the UK's largest single site employer go from strength to strength."
Transport Secretary Patrick McLoughlin announced in December that a decision about a new runway, expected that month, would be deferred for at least another six months due to environmental concerns.
The Department for Transport is still looking at the options for a third runway at Heathrow, a second runway at Gatwick and the plan put forward by Heathrow Hub to double the length of the existing northern runway at Heathrow.
