As an SFO on the 757, flying 400 hours a year (which is 100 hours more than the last two years!): matching the companies 8% pension contribution expect about £3500-3700 a month take home in the winter flying 2 days a month, flying 10 days a month in the summer taking home £4100. Normal FO salary is approx £6000 less off your gross annual salary so deduct about £250 a month from the above figures, however if you join on the 737 expect to fly double the above averaged out over the year and probably about another £300 a month in sector/duty pay (this is a guess as obviously i don't fly it)