From the RAF Northolt Defence Aerodrome Manual (DAM) I think this is what the others are carping about
:
4.
RWY End Safety Area (RESA). A RESA provides an undershooting or overrunning
aircraft with a cleared and graded area. The Northolt RESA details are as follows:
a. Eastern end (RWY 07 over-run):
i. RESA length is 180m and width is twice that of the RWY. There is a light
aggregate Arrestor Bed occupying the 90m furthest from the runway. No obstacles impinge
the RESA; however, the West End road, and associated obstacles, prevent the RESA
meeting the recommended distance of 240m.
ii. For aircraft approaching RWY 25, the RESA is based upon the threshold.
The RESA in the undershoot satisfies the minimum requirement in the Manual of Aerodrome
Design and Safeguarding (MADS), ie twice the RWY width by 90m. The Arrestor Bed
referred to above sits within the RESA.
b. Western end (RWY 25 over-run):
i. For aircraft approaching RWY 07, the RESA is based upon the displaced
threshold. The RESA in the undershoot satisfies the minimum requirement in the
Manual of Aerodrome Design and Safeguarding (MADS), ie twice the RWY width by
90m long.
ii. For aircraft departing RWY 25, the RESA length is 131m and width is twice
that of the RWY. There is a light aggregate Arrestor Bed 9occupying the 41m
furthest from the runway.
5.
.
Light Aggregate (Lytag) Arrestor Beds. Lytag Arrestor Beds are installed at both ends of
the RWY to compensate for the variance from the recommended RESA distances. The RWY 07
over-run Arrestor Bed sits within the RESA and is approximately 90m in length. The RWY 25 over-
run Arrestor Bed is located within the RESA. It is approximately 90m long; and narrows to
approximately 50m wide at the furthest point due to the A40 road infringing the southern edge of
the Arrestor Bed
Taken from:
http://www.londonvipairport.com/docs...tingManual.pdf
Seems that the RESAs don't make all the requirements although Lytag is a mitigation. What is well known is that there are plenty of civil licensed aerodromes that don't meet CAP168 either and have waivers with mitigations in the back of their Aerodrome Manuals.
As stated before - sour grapes...
LJ