Question: Elevation --- RWY

On Aug 11, 3:49*pm, C Gattman wrote:
On Aug 10, 12:41*pm, john89 wrote:

I got a question regarding the so-called "elevation", i.e. the highest
point of a runway. I have been told that the elevation is usually at
the threshold, right before the touchdown zone, in order to ensure an
easier take-off.

This information is available to pilots and updated periodically in
the Airport/Facilities Directory and the US Terminal Procedures, etc.

The A/FD defines it's "elevation" figure as "the highest point of an
airport's usable runways measured in feet from mean sea level." *In
addition, the A/FD lists runway slope when it is .3 or greater for
airports that have instrument approaches and elaborates based on other
runway criteria ( or than 8000', etc)

For IFR purposes, the A/FD and approach plates include a Touchdown
Zone Elevation (TDZE) for specific runways.

Pilots, particular under IFR, are expected to be familiar with runways
of intended use and, if required, alternate airports. We're strongly
encouraged to study other airports along the route in case we need to
divert. Cheers!

-Chris
CFI, KTTD

I must qualify for 'least sensitive' pilot here. I've made a number of
landings with Wx close to minimums, nasty weather, cross winds, night
time, and all that stuff. When I look up at minimums and see VASI and
runway locater lights and all that good stuff, I'm real happy to go
down the last couple of hundred feet, flare, and become earthbound
again. From the moment I go visual I really don't care what the actual
altitude of the runway I'm approaching is, I can see it, and know what
I have to do to fly the miss if needed. Does it really matter if it's
at 469 feet, or 500, at that point to those of us messing around in
SELs like Mooneys? What am I missing here? Even if a CAT 3 landing
(not in MY airplane!) the radar altimeter controls yoke back pressure
at flare, doesn't it? It's looking at actual wheels to ground
distances, not some indirect measure like "corrected altimeter
subtract field elevation equals air between wheels and ground.

The other minor blimp in all of this is I set the kollsman window,
then verify the altitude indication is within specification of
published altitude. The difference in altitude between the reference
datum and my static tube could be pretty significant -- something I
had not thought about before. 20 feet eats up a lot of a 50 foot error
budget.

In article ,
john89 wrote:

Still, the elevation of the RWY being in its centre (as claimed by D
Ramapriya) still denies any logic as far as I can see.

If the high point is in the middle, it's probably because that's what
the terrain looked like before the runway was built. Ground never comes
perfectly level, and it's often not worth the expense of fixing it to be
absolutely level just because you happen to be building a runway.

--
Mike Ash
Radio Free Earth
Broadcasting from our climate-controlled studios deep inside the Moon

"jan olieslagers" wrote in message
...
john89 schreef:

Alas, no rule without exception ;-)


That's true enough, but on top of that the rules that do exist have their
bounds, geographical or other.
One example: here in Belgium, we have the notion of an "active runway" and
this is communicated either per radio (on controlled aerodromes) or in the
signal square. But in France the concept of an active runway is not
universally applied (to say the least), I remember hearing a visiting
pilot inquiring what run runway to use, and getting for answer "ah, you
know, there's not too much wind, you just pick the 12 or 30 as you
prefer..."


KA

If the winds are calm (4 Kts, IIRC) and there is no traffic, you could get
a similar response here in the US; although, other factors are trivial, some
airports do have a preferred take off direction for noise abatement. I
suppose that the approved "phraseology" would be different, but the sense of
it should still work.

Peter

"a" wrote in message
...
On Aug 11, 3:49 pm, C Gattman wrote:
On Aug 10, 12:41 pm, john89 wrote:

I got a question regarding the so-called "elevation", i.e. the highest
point of a runway. I have been told that the elevation is usually at
the threshold, right before the touchdown zone, in order to ensure an
easier take-off.

This information is available to pilots and updated periodically in
the Airport/Facilities Directory and the US Terminal Procedures, etc.

The A/FD defines it's "elevation" figure as "the highest point of an
airport's usable runways measured in feet from mean sea level." In
addition, the A/FD lists runway slope when it is .3 or greater for
airports that have instrument approaches and elaborates based on other
runway criteria ( or than 8000', etc)

For IFR purposes, the A/FD and approach plates include a Touchdown
Zone Elevation (TDZE) for specific runways.

Pilots, particular under IFR, are expected to be familiar with runways
of intended use and, if required, alternate airports. We're strongly
encouraged to study other airports along the route in case we need to
divert. Cheers!

-Chris
CFI, KTTD

I must qualify for 'least sensitive' pilot here. I've made a number of
landings with Wx close to minimums, nasty weather, cross winds, night
time, and all that stuff. When I look up at minimums and see VASI and
runway locater lights and all that good stuff, I'm real happy to go
down the last couple of hundred feet, flare, and become earthbound
again. From the moment I go visual I really don't care what the actual
altitude of the runway I'm approaching is, I can see it, and know what
I have to do to fly the miss if needed. Does it really matter if it's
at 469 feet, or 500, at that point to those of us messing around in
SELs like Mooneys? What am I missing here?

Funny you should ask... :-)

Speaking as a former avionics technician and also student pilot, who also
rode "shotgun" on a few single pilot IFR flights back in the day, you are
exactly correct. It just happens that, in addition to the dedicated
"simmers" who stop by from time to time, this forum also serves as a source
of information for a lot of beginning students--and also for future pilots
and other interested citizens who have never been inside the airport fence.
Therefore, they are not necessary aware of which portions of the information
which is required to be surveyed, and entered into databases and onto
charts, arereally trivial in normal operations.



Even if a CAT 3 landing
(not in MY airplane!) the radar altimeter controls yoke back pressure
at flare, doesn't it? It's looking at actual wheels to ground
distances, not some indirect measure like "corrected altimeter
subtract field elevation equals air between wheels and ground.

I have no personal experience with Cat 3, so I can not address the
interconnection between the radio altimeter and the autopilot; but...

Back in the day, I was a "fill in" for the regular radio altimeter
technician--so here foes: The radio altimeter, which provides the
information regarding the flare in precision approaches, measures the
distance between the ground and the radio altimeter antenna--corrected for
the height of the antenna above the ground in the typical landing attitude.
On large transport category aircraft, that is typically several feet lower
than the antenna position when the aircraft is at rest. So, in practice,
you are exactly right about the reading of the radio altimeter in the
process of landing with the expected attitude and flap deployment.

BTW, on very large aircraft such as the Boeing 747, where the pilots eye
level at the time of touchdown is too high to give a reliable height
indication relative to the runway, it is common to also use the radio
altimeter as an information source in initiating the flare.

Peter

The other minor blimp in all of this is I set the kollsman window,
then verify the altitude indication is within specification of
published altitude. The difference in altitude between the reference
datum and my static tube could be pretty significant -- something I
had not thought about before. 20 feet eats up a lot of a 50 foot error
budget.

On Aug 11, 1:18*pm, john89 wrote:

Apparently there are just now "absolute" true rules such as:

Airplanes always land in the same direction as they took off.

Not so (although the norm in most cases, especially when wind is a
factor). I fly towplanes and gliders on weekends, and on days when
the wind is light, it's common to takeoff in one direction and land in
the opposite direction, as this saves taxy time and makes for a more
efficient (and actually safer, believe it or not, as it avoids power
vs glider conflicts on final) operation. Granted, this is on a huge
grass airstrip, so there is no head-on conflict - but I've even seen
cases of simultaneous takeoffs and landings in opposite directions,
with the planes/gliders passing on the ground in the middle of their
respective takeoff and landing rolls.

Definitely requires a good lookout!

Kirk
66

wrote

... I've even seen
cases of simultaneous takeoffs and landings in opposite directions,
with the planes/gliders passing on the ground in the middle of their
respective takeoff and landing rolls.

Yikes!

On Aug 14, 3:35*pm, "Jon Woellhaf" wrote:
wrote

... I've even seen

cases of simultaneous takeoffs and landings in opposite directions,
with the planes/gliders passing on the ground in the middle of their
respective takeoff and landing rolls.

Yikes!

Yikes for sure. That happened at the old Issaquah, WA gliderfield -
there were two commercial glider operations there, one at each end of
a nice grass strip, and each disliked the other. So when the winds
were light - you had to be heads up, to say the least! Plus there was
a jump school, so occasionnally you had to add a student under a chute
to the mix, and worst of all was the ultralight driver who would
wander around the pattern ...

Sigh, that was a fun place - always a crowd of onlookers ( I wonder
why!!). Shopping center now, of course.

Kirk
66

In article
,
" wrote:

On Aug 14, 3:35*pm, "Jon Woellhaf" wrote:
wrote

... I've even seen

cases of simultaneous takeoffs and landings in opposite directions,
with the planes/gliders passing on the ground in the middle of their
respective takeoff and landing rolls.

Yikes!

Yikes for sure. That happened at the old Issaquah, WA gliderfield -
there were two commercial glider operations there, one at each end of
a nice grass strip, and each disliked the other. So when the winds
were light - you had to be heads up, to say the least! Plus there was
a jump school, so occasionnally you had to add a student under a chute
to the mix, and worst of all was the ultralight driver who would
wander around the pattern ...

Sigh, that was a fun place - always a crowd of onlookers ( I wonder
why!!). Shopping center now, of course.

Funny. At my club, if we have a glider hooked up and ready to take off
on the pavement, and another glider on final for the parallel grass, we
will usually hold the takeoff until the landing glider is down and
stopped just to make sure everybody has the maximum number of options in
case Bad Stuff ensues.

The past is a different country, for sure.

--
Mike Ash
Radio Free Earth
Broadcasting from our climate-controlled studios deep inside the Moon

On Aug 11, 1:18 pm, john89 wrote:

Apparently there are just now "absolute" true rules such as:

Airplanes always land in the same direction as they took off.

As I said befo it all depends on where you are. Take a look at
Gap-Tallard LFNA on a sunny day and you will see glider tugs AND
paradrop planes like Twin Otters taking off one way and landing in the
other - for efficiency indeed. Quite funny to take off from the 21 and
hear a Pilatur Porter announce finals for the 03! I suppose one gets
used to it.
KA

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.

Jim




On Aug 11, 1:18 pm, john89 wrote:

Apparently there are just now "absolute" true rules such as:

Airplanes always land in the same direction as they took off.