It's 9.30pm. Air France flight 195 from Paris has just crash-landed at George Best Belfast City Airport.
Almost instantly the cabin bursts into flames. Smoke fills the dusk lit skies and debris is scattered along the runway. There are 65 people on board.
Immediately, the Belfast City Airport Fire Service crew roll into action. Their sirens can be heard blaring across the airfield as they rush to contain the fire, make the area safe then look for survivors. At the same time the police, ambulance service, hospitals and fire service are alerted and within minutes emergency response crews are at the scene.
The Northern Ireland Fire and Rescue Service helps to contain the scene, the police set up a perimeter and the Ambulance Service sets up a makeshift triage area.
Belfast has never experienced an air disaster of this magnitude before. How will our emergency services cope?
It is this very question that all three major services as well as George Best Belfast City Airport hope to answer as they take part in a mock air disaster at the airport tonight.
Around 200 personnel will take part in the exercise.
By law, the Civil Aviation Authority requires airports to test their response times and skills in conjunction with the emergency services to make sure they are prepared.
But the exercise also allows for each individual service to test their area of expertise, something which all have said is invaluable.
Dr David McManus, medical director for the Northern Ireland Ambulance Service, explained paramedics were used to responding in a similar manner to different types of emergencies. However with an emergency such as a plane crash, the protocol changes.
"We respond in a completely different way than we would normally," Dr McManus explained. "This is because it is part of an integrated response. Normally we have eight minutes to respond to a 999 call and we would treat this as a category A call but we are dependent on the other services.
"What is different for us is that we have to implement a system of triage. There are so many different types of injuries that we have to assess from life-threatening to shock. But none of this can take place until the scene is clear."
It is this inter-agency co-operation that PSNI Chief Superintendent George Hamilton said is the main reason for the mock exercise.
Practising allows them to identify any glitches in the co-ordinated response and to build better working relationships and eliminate any cross-over between roles.
The Civil Aviation Authority requires fire crews to be able to respond within two minutes.
The 33 firefighters at the City Airport regularly practise to ensure they meet the limit.
However, it is only in a scenario such as tonight's, that they can really test their effectiveness.