Thanks to input from COPA member Trevor Lyons, last month’s
“COPA Newsletter,” raised issues regarding missing information on current GPS
databases. Douglas Mein, Nav Canada director, Air Navigation Services and
Airspace Branch, sent the following reply:
“There are two separate problems raised regarding GPS receiver databases:
missing single-letter identifier NDBs; and the depiction airspace boundaries.
The joint Transport Canada/Nav Canada GNSS Implementation Team (GIT) discussed
these problems at its March 22, 2002 meeting, and team members cooperated to
prepare this reply.
“Databases have been used in aviation for many years in RNAV avionics, but the
recent introduction of GPS and the availability of RNAV (GPS) approaches have
added a new dimension and revealed various database problems. GIT members have
devoted considerable effort to identifying problems and finding solutions. They
have also contributed to the development of new database standards aimed at
resolving the problems. The focus has been on data used for IFR flight because
pilots flying VFR can use GPS as an aid, but not for primary guidance. In fact,
there is no functionality standard for handhelds or VFR panel-mount GPSs. There
is an installation standard for the panel-mounts.
“Correspondence and GIT research reveal that single-letter NDBs are treated in
different ways in different avionics, and in many cases the treatment causes
problems for pilots. Nav Canada recognizes that the only way to resolve this
problem is to assign new two-or three-letter identifiers to these NDBs. This
involves finding unique identifiers and making changes to the NDB equipment. Nav
Canada has started this process, and the changes will be made as soon as
possible. The timing depends on the availability of company technicians.
“The correct depiction of airspace boundaries is important for VFR operations,
but not for IFR. Some IFR-certified avionics depict airspace and provide alerts,
but most pilots deselect these features when flying IFR, because they add
irrelevant clutter to map displays and generate alerts that are not pertinent to
IFR flight. In any case, there is no standard governing the way avionics (even
IFR avionics) handle airspace boundaries, so avionics manufacturers do their
best to process and depict this information.
The result is not subject to certification. It is therefore important to stress
that pilots flying VFR must use current maps and charts and maintain situational
awareness through visual reference to the ground.
“Nav Canada will resolve the problem with single-letter NDBs. In addition, GIT
members will work with Transport Canada and COPA to draft a Safety Letter and
COPA news articles warning pilots against relying completely on GPS avionics.”