Butt Report
The Butt Report, 1941, found that on average only one in three RAF bombers claimed to have reached the target and, of these, only one in five bombed within 5 miles of it, a figure that fell to one in 15 on a moonless night.
So only 1 bomb in 45 got within 5 miles of its target under those conditions.
The Operations Research Group were given the task of identifying the problems, and providing solutions.
ORG calculated, from ‘real world’ photographic data, that the Dead Reckoning 50% Band of Error would have been 24 miles radius after the 3 hour flight to Berlin.
DR Errors on a UK to Berlin flight:
A 1o error in heading gives an across track error of 10 nautical miles.
A 10 knot error in the across-track component of wind gives an across track error of 10 nautical miles.
A 10 knot error in the along-track component of wind gives an along- track error of 30 nautical miles.
A 1 minute error in bomb release gives a 3 nautical mile along- track error.
A pencil line is ¼ mile wide on a 1:500,000 plotting chart.