The Red Arrows' patriotic red, white and blue smoke trails are set to become more environmentally-friendly as the MOD looks to replace the diesel solvents used with greener choices.
The RAF aerobatic team's 645mph Hawk T1 jets based at RAF Scampton currently blow the red and blue smoke by mixing coloured dye with a diesel solvent injected into the hot exhaust of the engine.
A pre-procurement notice issued by the MOD this month reveals that defence chiefs want to introduce an "environmentally friendly coloured smoke dye and a diesel solvent alternative".
Air Chief Marshal Sir Mike Wigston, the Chief of the Air Staff, has publicly pledged the RAF's commitment to become greener.
The pre-procurement notice states: "Defence Equipment and Support, a bespoke trading arm of the Ministry of Defence (the authority), is conducting early market engagement for a potential future procurement of environmentally friendly coloured smoke dye and a diesel solvent alternative to 'carry' said dye, for aerobatic displays.
"For the display aircraft to produce coloured smoke during display, dye is mixed with a solvent and stored on a pod attached to the aircraft.