LORAN (long range navigation)
- operates in the low frequency band (90-110 KHZ)
- operated by U.S. Coast Guard
- uses 1 master station and 2 secondary stations to calculate 2 LOPS (lines of position) to determine your location
- range is as much as 2000 miles over the water because the signals follow the curvature of the earth
- similar to a ground GPS
- multiple stations to calculate position
RNAV (area navigation) it allows pilot to fly a selected course to a predetermined point without the need to fly over ground based navigation facilities by using waypoints
- RNAV is line of sight because it requires an actual VORTAC or VOR/DME system to create a waypoint, must be within range of the parent VORTAC
- the computer creates the “pseudo” VORTAC or VOR/DME by adding a vector
- uses VOR to create signals for pseudo way points
- similar to a ground based GPS
3 components of GPS
- satellites
- ground components
- receiver
Satellites
- 30 satellites that orbit the every 12 hours
- 3 spares
- minimum of 5 satellites will be in view at all times anywhere on earth
Ground components
- there are 4 control stations
- 1 main control station in Colorado Springs
- the DOD controls the satellites, monitor position, times and make any adjustments
Receiver
- antenna (located on the tail)
- receiver
There are 4 page groups for our GPS receiver - NAV group; map, position, satellite status
- WPT (waypoint) group; airport location, runway, frequency, approach, arrival, departure, intersection, NDB, VOR, and user waypoints
- AUX group; RAIM prediction, display contrast
- NRST (nearest group); nearest airport, intersection, NDB, VOR, user waypoint, center, flight service, and airspace
RAIM (receiver autonomous integrity monitoring)
- a system used to verify the usability of the received GPS signals and warns the pilot of any malfunction in the navigation system. RAIM is required for IFR certified GPS units.
- GPS needs to communicate with 5 satellites to get RAIM
- can get RAIM prediction from FSS briefer or check the AUX page group
- if you don’t have RAIM you can’t do the approach, if it fails you must
1. Stop descending
2. Proceed to the MAP and carry out MAP procedures
Warning or INTEG
- lets you know that the GPS is not working properly
- fly to MAP but do not descend, GO missed
GPS startup and self test procedure
- check the date to ensure the data base is current (updated every 28 days)
- self test shows the GPS and HSI are showing the same information
Waypoint
- a point defined by latitude and longitude used for navigation and position reporting
HSI/GPS coupling:
When in GPS mode both instruments will indicate the same information
Information provided:
- position
- ground speed
- estimated time en-route (ETE)
- distance off desired track
Advantages over other systems
- non-precision approaches can be preformed anywhere (oil rigs, hospitals ext…)
- no need for line of sight from ground based NAVAID
- not affected by the weather
- no need to fly over ground based NAVAID
Disadvantages:
- not accurate if needed satellites are not in view
Use of GPS for flight (AIM 1-1-19)
- GPS must comply with TSO-C129 (technical standard order) “IFR flight certified
- only approaches in current data base are authorized for use
- must have alternate means of navigation (VOR, NDB, LORAN)
- GPS database must be updated every 28 days if used for IFR flight
- hand held can’t be used as primary GPS also can’t be used for approaches
GPS sensitivity
3 different phases
- En-route phase
- more than 30 NM from airport
- full scale deflection 5 NM center to one side (1 NM per dot) - Terminal phase
- less than 30 NM from airport, but farther than 2 NM from FAF
- full scale deflection is 1 NM each side of center - Approach mode (must have RAIM)
- 2 miles from final approach fix
- .3 NM deflection each side of center
VHF direction finding
- special antenna at ATC ground base facility that can detect the direction of VHF-COM signals
- voice communication
- simply pushing the microphone will enable VHF DF
- directional information is displayed to a controller on a radar screen, then the controller can advise the pilot with a heading to fly
- controller can determine a fix with readings from 2 or more DF stations
- no special airborne equipment is needed
- mainly used in emergency situations- lost procedures
