Britain's airports regulator will not face legal action over a stowaway who fell to his death in west London.
Richmond Council's application for a judicial review against the Civil Aviation Authority was rejected by a High Court judge.
But council chiefs say they are still seeking safety reassurances following the death of a man found on the top of an office block in Richmond last June.
The man is believed to have hidden in a British Airways (BA) jet from South Africa to London and fallen to his death when the plane's landing gear opened on the approach to Heathrow .
A second man was found at the airport that morning in the aircraft's undercarriage after remarkably surviving the perilous journey.
The council says it was the third time since 2012 that the body of a stowaway on a BA plane bound for Heathrow had landed in the borough.
Richmond Council leader Lord Nicholas True said: "A number of tragic international events over the past few months have shown us the importance of rigorous and robust airport security procedures at the points where planes bound for London are boarded.
"I am not prepared to let the matter rest and have been assured now at a high level in government that it is being taken seriously following the Sinai attack.
"With the future of Heathrow still hanging in the balance, surely the protection of our capital is our first duty.
"Clearly there is a security problem at a number of international airports. Until this is addressed it is sheer folly even to be considering expanding Heathrow allowing hundreds of thousands more flights a year over London and potentially doubling the risk that someone or something might be on board without permission."
The council believes the CAA should be accountable as it is responsible for investigating the extent of enforcement action taken to prevent airline stowaways falling from planes.
But it said a High Court judge ruled it was not the CAA's responsibility to investigate and take action over such incidents.
A spokesman for the CAA said: "The UK Civil Aviation Authority is responsible for regulating security at UK airports only. It is not responsible for regulating security at airports outside of the UK.
"This matter has now been reviewed by a High Court Judge who has agreed that it is not the CAA's responsibility to investigate security-related incidents that occur outside of the UK or to take action in relation to stowaways."
Richmond Council has called for more to be done to prevent such tragedies, for the safety of both potential stowaways and those living under the flight path.
It says it has written to both BA and the Department for Transport demanding an investigation into how stowaways are able to access planes - especially in the wake of an aircraft being brought down in Sinai, Egypt, last year when a bomb was planted on board.
getwestlondon has contacted the CAA, BA and the Department for Transport for comment.
