Defence

Another area of the selection process criticised by the US Government Accountability Office involved basic omissions and errors that tilted the tanker contract award to Northrop.

For example, the A330 is limited by flight-control software to a maximum speed of 330kt (610km/h), which falls short of the minimum speed that the USAF requires to conduct a so-called "overrun" manoeuvre.

Northrop first responded to this shortfall by advising the USAF to change its manoeuvre speed, but lost the argument. The USAF then accepted Northrop's claim that the A330 already safely achieves higher speeds in dives. The GAO notes that a commercial aircraft's maximum operating speed applies to any flight regime, but the USAF evaluator was unaware of this.

Northrop's proposal also failed to explicitly account for a requirement to supply the first two years of organic depot support, despite repeated warnings by the USAF about the omission. Nevertheless, the USAF accepted Northrop's reply that it was simply an oversight.

Paul Meyer, Northrop's vice-president for the KC-30B, says: "We actually gave a larger commitment to the air force - irrespective of time - that we would be there when they needed the capability."

But the GAO is not convinced: "We find that it is far from clear whether or not Northrop Grumman's proposed schedule establishes that it would perform these services within the two-year timeframe."