T-45C TS, ADV, & IUT RIFP-01
Introduction to Radio Instruments
VII. Computing ground speed using TACAN/VOR DME
Sg 6, fr 2
2.7.5.1.5.1
INTRODUCTION TO RADIO
INSTRUMENTS
NOTE: To be able to compute ground speed while
maintaining a course to or from a TACAN/VORTAC
* SID procedures
station, the DME from station must be greater than
* Radial intercept procedures
or equal to the aircraft altitude in thousands of feet.
* Indications of station passage
* TACAN/VOR DME arc
DISTANCE (NM)
procedures
______________
X
60 = GROUND SPEED
* Voice procedures
* Ground speed computation
TIME (MIN)
procedures
* Wind drift correction
EXAMPLE: If the altitude is 30,000 ft (FL 300), DME
procedures
should be 30 nm or greater.
* Pt-to-Pt procedures
* Direct to a NAVAID
A.
Start timing with a whole number in DME
* VOR-TACAN/VOR DME
indicator
holding procedures
B.
After predetermined time (in minutes), check
Sg 6, fr 3
and note DME
DISTANCE (NM)
------------------------ X 60 = GROUND SPEED
TIME (MIN)
C.
Determine distance flown (every 1/10 nm equals
6 kts) and multiply distance by a number that
RULE: DME must be greater than or equal to the
aircraft altitude in thousands of feet.
corresponds to the amount of time traveled to
GROUND SPEED CALCULATION
get ground speed
FORMULA
EXAMPLE: Your distance flown is 6 on the
Sg 6, fr 4
DME indicator. Elapsed time is 1 minute, so 6
times 60 equals 360. Ground speed is 360 kts
(6 nm/min times 60 min/hr equals 360 nm/hr).
NOTE: The ground speed check requires
tracking directly to or from the station.
NOTE: To increase accuracy, check ground
GROUND SPEED
speed for more than 1 minute.
D.
The current calculated ground speed is shown
on the HSI display and the HUD navigation
cruise display
Page 1-25
(5-99) Original
Previous Page
