One would get the sense that the weather radar wasn't working well before either, otherwise how would they have flown into a hailstorm of that magnitude.
1.Weather radars have a hard time seeing hail - if it is 'dry'.
2.All types of hail may be carried many miles from fathering storm clouds.
This is how it can appear with no apparent warning - catching crews by surprise - in this case an unpleasant one.