David Niven did not receive an Oscar nomination for portraying Squadron Leader Peter David Carter in A Matter of Life and Death.
David Niven plays the man who gets into the most bizarre set of circumstances that leaves him fighting for his life in a most atypical sort of way. Largely this performance is based on Niven's charm. Niven has a charm but I have to say that it doesn't always work, and sometimes can be more obnoxious than charming such as in The Pink Panther. This is not the case here though where Niven uses it rather well to establish Peter as a fairly likable guy. This is not Niven really trying anything overly different here but rather just giving a performance to make it easy enough to follow Peter through his most unusual journey. There technically isn't that much more to his character here than that except for the love story he has and the whole idea of his dealing with the other world that he is forced to visit from time to time.
The whole aspect of the other world is supposedly kept to be possibly all in Peter's mind, although it doesn't really try too had in this respect, but nor does it really need to. Niven for the most part presents his interactions in a fairly matter of fact fashion, which certainly works well enough. The biggest challenge of Niven's is to present the way each visit seems to cause a slow deterioration of his physical state while he refuses to accept that he should die. Again Niven doesn't make too big a deal of this either, but again it works well enough of the film as he shows Peter slowly losing his physical resolve as the film progresses. Again there is not anything that special about what Niven does in this regard but what he does do works well enough for the film as a whole, and there is nothing to complain about unlike the final aspect of his performance.
That is the love story Peter has with an American woman June (Kim Hunter) who heard his "final words" over the radio before he jumped from his critically damaged plane failed to die.I have to say Hunter and Niven don't really have that much chemistry and I never felt anything special between them except for in the opening scene where they speak over the radio. In their opening scene Niven is quite good portraying Peter's excessively cheery and proper resolve even as he's basically indicating that's he's about to die. In turn Hunter's reactions are effective and together they connect simply in the sense of both feeling this loss of a human life together. It's a powerful moment but I'd say the only time where their relationship truly works. Interestingly enough the film has enough going on otherwise that he doesn't matter the central relationship isn't even anything special. Niven as well gives a suitable performance throughout, but he is very much overshadowed Powell and Pressburger's vision as well as the supporting cast.