Position Recorders allowed the US for Silver badges?

A question I would like to see settled, important for those who fly
beneath controlled airspace (CAS), is how to ensure that the CAS has
not been entered. (In the UK at least, this is treated as a reason to
not grant claims.)

If the base of CAS is defined by flight level, GPS altitude does not
establish whether or not CAS was violated unless some elaborate
computations are done, AIUI. Baro is needed.

If CAS is defined by height or altitude, GPS may suffice.

As our moving map software is using height/altitude data for glide
angle to goal etc., can it mislead people to think that they are clear
of CAS when on fact just up inside it?

If the logger is the source of the GPS engine for the moving map, this
seems to me to be an issue.

I was recently in a comp where one pilot on successive days was
penalised for just slightly going up into CAS. He did not mean to. I
suspect that the FL/Altitude difference may have played a part.

Chris N.

Tim, thanks. By your silence on the subject, I presume you agree with
my first point: that moving map software using (I think) only GPS
altitude data is apt to mislead pilots into thinking they are below
(or above, depending on QNH on the day) CAS which is defined by flight
levels.

I was short cutting a bit when I said “may”, in “If CAS is defined by
height or altitude, GPS may suffice”. What I was hinting was that at
low levels (e.g. Stansted UK CTA at 1500’), and when QNH and ascents
are close to standard atmosphere, you would be unlikely to be a few
hundred feet wrong.

In principle, yes – FAI requires baro. So does the law in the UK. So
our moving map warning, re height, are undependable.


Chris N.

Chris Nicholas wrote:
Tim, thanks. By your silence on the subject, I presume you agree with
my first point: that moving map software using (I think) only GPS
altitude data is apt to mislead pilots into thinking they are below
(or above, depending on QNH on the day) CAS which is defined by flight
levels.

I was short cutting a bit when I said “may�, in “If CAS is defined by
height or altitude, GPS may suffice�. What I was hinting was that at
low levels (e.g. Stansted UK CTA at 1500’), and when QNH and ascents
are close to standard atmosphere, you would be unlikely to be a few
hundred feet wrong.

In principle, yes – FAI requires baro. So does the law in the UK. So
our moving map warning, re height, are undependable.


Chris N.

I am not sure why you seem to be referring to this issue as in the
moving map software or why you seem to assume all "loggers" only pass
GPS based altitudes.

All popular PDA/PNA software that I am aware of is capable of (and
flight computers that support airspace all) will work with pressure
altitude. You want this to all work as it should with "moving map
software" then buy a flight computer/flight recorder etc. that outputs
pressure altitude data over NMEA. Pilots who do not have that better get
the need to defer to their altimeter. As for use for determining
airspace violations post-flight I think this is such a pain in the neck
that pressure recording should always be required (so we likely agree on
that).

I really think the whole position recorder idea from the IGC was
unnecessary and results in yet more confusion. And that is on top of the
already multiple levels of approvals for IGC flight recorders, often
separate ENL options, confusing IGC/FAI rules, different OLC rules,
crappy support for popular legacy products (e.g. Cambridge), ... all
that just ads up to a much worse end-user experience than it should be.

Darryl

Darryl, thanks. I did not know that “All popular PDA/PNA software that
I am aware of is capable of (and flight computers that support
airspace all) will work with pressure altitude.”

So I was seeking clarification.

I use Volkslogger and Winpilot, set up and connected by an agent/
vendor. I really don’t know the technicalities.

There was some correspondence recently on the (mainly UK)
gliderpilot.net which caused me to raise the question.

Regards – Chris.

Chris

Winpilot (Advanced and Pro) will use pressure altitude for airspace
violation warnings etc. The pressure altitude is in the Volkslogger's
PGCS NMEA sentence--assuming that sentence is turned in the Volkslogger
setup. That setup is described well in both the Winpilot and Volkslogger
manuals.

That pressure altitude is of course cockpit ambient pressure and may
disagree with a proper static source. But that is what you have an
altimeter for. And it's the cockpit static that gets recorded in the IGC
file. Pilots should compare these altitudes and effects of opening
cockpit vents etc in flight.

Darryl

Chris Nicholas wrote:


Darryl, thanks. I did not know that “All popular PDA/PNA software that
I am aware of is capable of (and flight computers that support
airspace all) will work with pressure altitude.�

So I was seeking clarification.

I use Volkslogger and Winpilot, set up and connected by an agent/
vendor. I really don’t know the technicalities.

There was some correspondence recently on the (mainly UK)
gliderpilot.net which caused me to raise the question.

Regards – Chris.

Thanks again. Got it now!

Chris N.