Garmin G1000 Manual page 8

• APV
Approach with vertical guidance is an International Civil Aviation Organization (ICAO)
term referring to specific ICAO criteria adopted in May 2000.
classification allows stabilized descent using vertical guidance without the accuracy
required for traditional precision approach procedures. The US has developed criteria for
lateral/vertical navigation (LNAV/VNAV) and LPV approach procedures that meet this
approach classification. LNAV/VNAV and LPV approaches provide guidance in both the
lateral and vertical planes.
• SBAS
Satellite-based augmentation systems use satellites and networks of ground stations to
provide improved accuracy for received GPS satellite signals.
countries are working with the International Civil Aviation Organization (ICAO) to
standardize satellite-based augmentation systems (SBAS) globally. WAAS is an SBAS
currently being implemented in the United States
2. Describe how WAAS provides improved accuracy.
The Wide Area Augmentation System (WAAS) uses a network of ground stations to
provide necessary corrections to received GPS SPS navigation signals. Precisely surveyed
ground reference stations are strategically positioned across the country, including in
Alaska, Hawaii, and Puerto Rico, to collect GPS satellite data. Using this information, a
message is developed to correct any signal errors. These correction messages are then
broadcast the same frequency as GPS signals by communication satellites to receivers on
board aircraft. WAAS is designed to provide the additional accuracy, availability, and
integrity necessary to enable users to rely on GPS for all phases of flight, from enroute
through approach for all qualified airports within the WAAS coverage area.
WAAS supplies two different sets of corrections:
clock, etc.) and
independent (i.e., they apply to all users located within the WAAS service area). The
second set of corrections is area specific. WAAS supplies correction parameters for a
number of points (organized in a grid pattern) across the WAAS service area. The user
receiver computes ionospheric corrections for the received GPS signals based on
algorithms which use appropriate grid points for the user location. Furthermore, the
appropriate grid points may differ for each GPS satellite signal received and processed by
the user receiver, since GPS satellites are located at various positions in the sky relative to
the user. The combination of these two sets of corrections allows for significantly
increased user position accuracy and confidence anywhere in the WAAS service area.
3. Explain the capabilities of TSO-C146a GPS equipment during instrument approaches, per
the AIM.
The equipment automatically utilizes WAAS error corrections for safe navigation of
LNAV/VNAV instrument approaches.
vertical guidance.
specifically for WAAS, providing ILS-like performance.
4. Equipped with TSO-C146a GPS equipment, what other navigational instruments must your
aircraft have on board to navigate in National Airspace?
Using TSO-C146a GPS equipment, a pilot could legally navigate solely by use of WAAS
GPS, even in areas where VOR or NDB reception is poor or non-existent.
C129/C129a systems require the presence of another approved navigation system
appropriate to the intended route of flight.
4
2
Ionospheric parameters. The first set of corrections is user position
This equipment can also navigate LPV approaches developed
GIFD Pilot's Training Guide
1
corrected GPS parameters (position,
These approaches provide both horizontal and
This approach
Internationally, many
All TSO
190-00368-05 Rev. B