I'd push back on that one, explaining that it was an EasyJet aircraft that hit your wife's EasyJet aircraft.

EU261 caselaw has two prongs to the 'extraordinary circumstances' test: that the incident must be extraordinary and that the incident could not have been avoided even if all reasonable measures had been taken.

Two planes colliding probably would count as extraordinary circumstances, yes, but EasyJet cannot argue that it could not have been avoided if all reasonable measures had been taken. Making sure their pilots don't drive into things is a reasonable measure.

If another airline had crashed into your wife's plane it may be different.