Question to the Ministry of Defence:

To ask the Secretary of State for Defence, what steps have been taken to eliminate uncommanded wing drop when manoeuvring the F-35B.

The Joint Strike Fighter programme has completed an extensive period of dedicated development flight test to both assess the impact of uncommanded wing drop (called transonic roll off) and mitigate its impact. The results of flight test have been to use a combination of control surface inputs from the leading edge flaps, trailing edge flaps and horizontal tails which have been applied differentially using software driven flight controls when the aircraft is operating at elevated angles of attack in the transonic flight condition.

It is extremely difficult to totally remove transonic roll from the transonic area of the flight regime, but these changes in the software control laws have lessened its severity and it has been assessed that they are now acceptable by the experienced flight crews that have flown with them. The programme leadership, which includes the UK Ministry of Defence, has concluded that they will allow the aircraft and pilots to execute the mission. The programme will continue to monitor and refine the flight control laws throughout the life of the aircraft as the aircraft's capability develops and if the target set and mission changes.