Heathrow Director - an uneducated question here but sometimes the Tower issues a caution warning on approach. Along the lines of ' 2.5 miles behind a 777, caution wake turbulence'.
When I have heard this, it almost sounds as if the Tower are apportioning blame to the following a/c, I know that they are not but why does that scenario occur in the first place ?
To the extreme, I once heard the Tower requesting an a/c to fly a zig-zag pattern to increase seperation on finals because of the limited distance from the preceding a/c.
Fairly familiar with the holding patterns and the flows into EGFF so not in any way a criticsm or finger pointing post - I am simply curious.
Cheers