My error. We did a massive cut and paste job on the runway about 15 years
ago and took an average 3% slope down to 2.1%

But that's not the point. THe point is that both ends of the runway are
surveyed and the elevation at that end marked for altimeter setting.

THe other point is that instrument approach charts list TDZE (touch down
zone elevation) for just this reason ... not many airports have EXACTLY the
same elevation at both ends, not even in Kansas, Toto.

Jim



"a" wrote in message
...
On Aug 15, 11:18 am, "RST Engineering - JIm"
wrote:
KGOO (formerly O17, Grass Valley CA) has a 3% slope to the runway. The
firebombers (air tankers Grumman S2Ts) always take off downhill and land
uphill. Night operations for everybody are notamed the same because of the
trees at the east end of the runway.
text -

- Show quoted text -

Jim, a 3% slope would mean 3 feet of altitiude change per 100 feet of
runway. On a 4000 fooot runway that means 120 feet. My question is,
if the tiedowns are near the low end, when the altimeter is set to
local pressure, if the altimeter is calibrated and the field elevation
is taken as the highest point on the runway, there would be a 120 foot
'error'. For a pilot starting an IFR flight who didn't know better,
that's outside the 75 foot error allowed. Are there special
procedures published for that airport or others like it?

SInce the takeoffs there are downhill, the altimeter would read
within tolerance if checked during run-up at the take off end (if one
knew of the problem) but I am wondering about the more general case.