From handling the big jets, by D.P.Davies.
Quote:
The effect of the wing planform characteristics (sweep). In practice the whole wing does not stall at the same instance. A simple swept and tapered wing will tend to stall at the tips first because the high loading outboard, due to taper, is aggravated by sweep back. The boundary layer outflow also resulting from sweep reduces the lift capability near the tips and further worsens the situation. This causes a loss of lift outboard (and therefore aft) which produces pitch up. A lot of design sophistication is needed, including the use of camber and twist, leading edge breaker strips, fences, etc., to supress this raw quality and get an inboard section stalled first so that the initial pitching tendency is nose down. However, when a highly developed swept wing is taken beyond its initial stalling incidence the tips may still become fully stalled before the inner wing in spite of the initial separation occuring inboard. The wing will then, therefore, pitch up.