"Jose" wrote in message
news

Well, actually it could. Any navigation system which tells the pilot he
is in one place when he is actually in another, which is used by a pilot
who is in IMC, could cause the pilot to place himself in a position from
which a collision with a mountainous surprise is unavoidable. While it is
true that the navigation system did not move the mountain, the effect on
the pilot is the same.


The controller will alert the pilot to the navigational error. The use of a
handheld GPS for IFR enroute navigation in US controlled airspace is no more
hazardous than being vectored.



It may be that a VFR GPS which is clipped to the right part of the yoke
will provide better guidance in and among ridges than an IFR ADF. But
there is a risk, not present with an IFR installation of anything, that
the highly accurate VFR GPS unit will fall off the yoke at the wrong
moment, perhaps while outside of radar coverage, or on an approach.


We're talking about enroute use, not approaches. If the aircraft is out of
radar contact it will be routed via airways or within the usable limits of
navaids. The pilot will be able to compare the GPS to his VOR or ADF to
verify it's accuracy. The use of a handheld GPS for IFR enroute navigation
in US controlled airspace is no more hazardous than use of VOR along
airways.



There
is a risk (present in VFR and IFR units) that the data displayed is
incorrect - it has happened in our aircraft (Danbury moved four hundred
miles without giving any notice to Ridgefield); IFR units are (presumably,
though only the manufacturer really knows) tested to higher standards.
There is a risk that the pilot will be unable to maintain the more
challenging scan required by certain VFR GPS "installations" and thus will
end up elsewhere than where he thought he was. Outside of a radar
environment, in hostle terrain, this could activate the ELT.


The controller will alert the pilot to the navigational error. The use of a
handheld GPS for IFR enroute navigation in US controlled airspace is no more
hazardous than being vectored. If the aircraft is out of radar contact it
will be routed via airways or within the usable limits of navaids. The
pilot will be able to compare the GPS to his VOR or ADF to verify it's
accuracy. The use of a handheld GPS for IFR enroute navigation in US
controlled airspace is no more hazardous than use of VOR along airways.



As for relying on controllers to "nudge" the aircraft back on course in a
radar environment, this would be true primarily in airspace controlled by
Steven P. McNicoll, who mever nakes mistakes. Merely human controllers
might, for any number of reasons incomprehensible to Steven, miss
something, allowing the pilot's error to terminate the flight prematurely.


It is not an option, it is required of all controllers. If you can't trust
the controller to perform his job as he is required to do you cannot operate
IFR in controlled airspace.