In accordance with MATS Part 1 Farnborough instruct Blackbushe aircraft to squawk ‘standby’ to de-clutter their radar, but in doing so lose the advantage of TCAS. The CAA ATSSD policy to squawk standby is at variance with CAA GAD policy of squawking Mode A and C where possible in order to retain the benefits of TCAS. The Trial suspends the use of MATS Part 1, Section 1, Chapter 5, Page 7, Paragraph 4.7.1, sub-para b at the trial airfields. Using a discrete squawk such as 7006 means that radar agencies suffering from clutter can now filter out the ATZ traffic 7006 squawks whilst retaining TCAS benefits and 7000 conspicuity in the ‘open FIR’. Farnborough 'pair' the 7006 code to display a 'B'. The trial may reinforce the case for a more general policy change in MATS Part 1 to allow SSR in the traffic pattern at aerodromes generally. The trial is necessary in order to provide confirmation that no significant ATC radar display or TCAS issues would arise from such a change.