GPS 400 Pilot’s Guide and Reference
190-00140-60 Rev. E
SECTION 12 – MESSAGES,
ABBREVIATIONS, & NAV TERMS
12-12
Term
Description
EPE (estimated
position error)
A measure of satellite geometry quality and additional factors, expressed as a horizontal
position error in feet or meters
ESA (enroute safe
altitude)
The recommended minimum altitude within ten miles, left or right, of the desired course on an
active flight plan or direct-to
ETA (estimate time of
arrival)
The estimated time at which the aircraft will reach the destination waypoint, based upon
current speed and track
ETE (estimated time
enroute)
The time it will take to reach the destination waypoint, from present position, based upon
current ground speed
FF (fuel flow)
The fuel flow rate, expressed in fuel units per time (e.g., gallons per hour)
FOB (fuel on board)
The total amount of usable fuel on board the aircraft
GS (ground speed)
The velocity of the aircraft relative to a ground position
HDG (heading)
The direction an aircraft is pointed, based upon indications from a magnetic compass or a
properly set directional gyro
IND (indicated)
Information provided by properly calibrated and set instrumentation in the aircraft panel (e.g.,
indicated altitude)
LFOB (left-over fuel
onboard)
The amount of fuel remaining on board after the completion of a one or more legs of a flight
plan (or a direct-to)
LRES (left-over fuel
reserve)
The amount of fuel remaining on board after the completion of a one or more legs of a flight
plan (or a direct-to), expressed in time and based upon a known fuel consumption (flow) rate
MSA (minimum safe
altitude)
Uses Grid Minimum Off-route Altitudes (Grid MORAs) to determine a safe altitude within ten
miles of the present position
Grid MORAs are one degree latitude by one degree longitude in size and clear all reference
points within the grid by 1000 feet in areas where the highest reference point is 5000 feet
MSL or lower
If the highest reference point is above 5000 feet, the Grid MORA will clear the highest
reference point by 2000 feet
TKE (track angle
error)
The angle difference between the desired track and the current track
An arrow indicates the proper direction to turn to reduce TKE to zero
TRK (track)
The direction of movement relative to a ground position; also referred to as “ground track”
VSR (vertical speed
required)
The vertical speed necessary to descend/climb from current position and altitude to a defined
target position and altitude, based upon current ground speed
XTK (crosstrack error)
The distance the aircraft is off a desired course in either direction, left or right