Since waxing lyrical about him in the recent post in this forum -
http://www.pprune.org/forums/showthr...hreadid=108828
I just have to quote Davies on this:
Heavy Rain
In or beneath a violent thunderstorm it is possible to suffer extremely heavy rain of 50 grams per cubic metre (~= 1 inch per minute) and this could cause engine flame out. This rate, however, is extremely rare and occurs only in an area where the aeroplane shouldn’t be anyway. Leaving this and other exceptionally heavy rates aside we come to normal very heavy rain of 2 grams per cubic metre (= 2 in. per hour). This has no significant effect on the aeroplane or its engines, except that the water might impact on the pitot head and cause temporary fluctuations of airspeed, in the underreading sense, even with the heaters on. Free water can exist in large quantities at high altitudes down to extremely low temperatures. This can cause ice-accretion at a rapid rate due to the naturally low temperature of the outside of the aeroplane. Depending on the efficiency of the rain dispersal system forward visibility can be significantly reduced.
I wonder if that is why Boeing had their advice about adding 10 knots - not so much for speed as to correct the ASI? Now the trick is to land firmly and pull up whilst still staying on the presumably flooded runway.