the scaled QRA response, civilian air traffic controllers might see on their screens an aircraft behaving erratically, not responding to their radio calls, or note that it's transmitting a distress signal through its transponder. Rather than scramble Typhoons at the first hint of something abnormal, a controller has the option to put them on a higher level of alert, 'a call to cockpit'. In this scenario the pilot races to the hardened aircraft shelter and does everything short of starting his engines". On 4 October 2015, a final stand-down saw the end of more than 70 years of RAF Search and Rescue provision in the UK. The RAF and Royal Navy's Westland Sea King fleets, after over 30 years of service, were retired. A civilian contractor, Bristow Helicopters, took over responsibility for UK Search and Rescue, under a Private Finance Initiative with newly purchased Sikorsky S-92 and AgustaWestland AW189 aircraft. The new contract means that all UK SAR coverage is now provided by Bristow aircraft. In 2018, the RAF's vision of a future constellation of imagery satellites was initiated through the launch of the Carbonite-2 technology demonstrator. The 100 kg Carbonite-2 uses commercial off-the-shelf (COTS) components to deliver high-quality imagery and 3D video footage from space. From March 2020, as part of Operation Rescript, the RAF has been assisting with the response efforts to the COVID-19 pandemic in the United Kingdom. This has seen the service provide repatriation flights and aeromedical evacuations of COVID-19 patients, drivers and call-handlers to support ambulance services and medics to assist with the staffing of hospitals, testing units and vaccination centres. Under Operation Broadshare, the RAF has also been involved with COVID-19 relief operations overseas, repatriating stranded nationals and delivering medical supplies and vaccines to British Overseas Territories and military installations. Structure Senior management The professional head and highest-ranking officer of the Royal Air Force is the Chief of the Air Staff (CAS). He reports to the Chief of the Defence Staff, who is the professional head of the British Armed Forces. The incumbent Chief of the Air Staff is Air Chief Marshal Sir Mike Wigston, who was appointed in July 2019. The management of the RAF is the responsibility of the Air Force Board, a sub-committee of the Defence Council which is part of the Ministry of Defence and body legally responsible for the defence of the United Kingdom and its overseas territories. The