I have many thoughts on this, but the one that appears not have have been mentioned thus far is - "The Passenger reported that he twice told the pilot that the weather at Elstree was bad and recommended that he should not take off"
Call me a cynic, but he would say that wouldn't he? We've only got his word for that and he's hardly likely to turn round and say "oh yeah - i told him there were some holes around Elstree and really encouraged him to try" is he?
Whilst the texts are a matter of record, the contents of phone calls are not.