Question to the Ministry of Defence:

To ask the Secretary of State for Defence, what assessment he has made of the effects of buffeting and transonic roll-off on the ability of (a) the helmet-mounted display systems to display symbology and (b) gyroscopes in the inertial platforms to operate correctly on the Joint Strike Fighter F-35B.

The Joint Strike Fighter programme has completed an extensive period of dedicated flight test to assess the impact of buffeting and transonic roll-off on both the helmet mounted display and gyroscopes in the inertial platforms. The conclusion of these flight tests, which have used changes in the flight control laws to mitigate both conditions throughout the flight envelope, is that the helmet mounted display and gyroscopic equipment meet the required performance specification and are fit for purpose to allow pilots to execute the mission. It is only in one area of the flight regime where buffet makes screen symbology difficult to read, and this is at the extremes of the envelope and extremely short lived as the aircraft manoeuvres, it is considered that they can be overcome by pilot training. These flight trials have included UK test pilots who have agreed with the conclusions of the US experts from government and industry.