A Lockheed Martin spokesman said: “The F-35 programme has yet to formally test for lightning protection. We still have 4 years of Developmental Test ahead of us, before we actually begin formal Operational Testing. There is a plan in place for lightning testing to be completed in the future test plan, and for the jet to be appropriately equipped to fly in all weather. The plan is to conduct lightning test towards the end of the flight test programme. Because the testing has not be completed to date, we therefore have a lightning restriction of 25 miles at present for flight operations – this is obviously the safe, and sensible way to do business and supported by all involved in the programme.”