Very high speed at height isn't essential for MPA, superior fuel consumption and performance at lower levels are more important.
Originally Posted by
manccowboy
You have to ask why on earth a P8 (737) was ever considered for this role
At the risk of answering a question already tackled:
It depends on the operational requirement. To use the Nimrod figures, it could react and reach a patrol area 1000 miles from base in 3.5 hours. Unrefuelled it could remain there for 4 hours and be relieved by another Nimrod with 6 patrol cycles in 24 hours.
A Shackleton, the epitome of low and slow, could reach that patrol area in 6.5 hours and remain on patrol for 2-3 hours and thus need 10-12 patrol cycles and more aircraft and crews to do the job.
In addition the Nimrod would only be 3.5 hours late on a datum with the Shackleton nearly double that. It doesn't take a genius to calculate the respective circles of uncertainty. In the Nimrod case it could reach a point on the circumference in 10 minutes. In the Shackleton case in an hour.
These are of course extremes and the speed difference between a modern hi-fast or low and not so slow is not as extreme but it points up the need for speed.
In the case of SRMP the difference comes down to launch reaction time rather than sheer speed.