Peculiarities Of Navigation At Night - Kazan Helicopters Mi-17-1V Flight Manual

M,,·17·1B. Flight manual
object proper and find out its characteristic points selected in advance
that is rather difficult due to limited visibility of terrain.
Adherence iu this procedure is particuiariy important in iimited visibiiity
since even at small deviations from course the next reference object may
be left unidentified or fall out of the field of vision. These conditions in-
volve difficulties in helicopter navigation and in some cases may cause
loss of orientation.
(10) In the course of preparation for enroute flight investigate possible proce-
dures of restoration of orientation in route segments lacking characteristic
reference objects.
If the next reference object fails to appear at estimated time increase alti-
tude up to 100 to 150 m to improve the terrain observation.
When flying by day in normal weather conditions and at limited horizontal
visibility it is advisable to maintain altitude visually with periodical refer-
ence to the radio altimeter. In IFR flying use the pressure altimeter with
reference to the radio altimeter.
4.24.7. Peculiarities of navigation at Night
(1) Helicopter navigation at night has several peculiarities which include de-
terioration of conditions in which visual orientation is conducted due to
poor visibility of natural reference objects, difference of artificially illumi-
nated reference objects configurations from their true configurations and
difficulties in visual determination of distances to illuminated reference
objects.
(2) At night the range of radio navigation means and accuracy of navigation
data obtained by means of ADF deteriorate as well. Apart of this, deter-
mination of navigation data with the use of common means and observa-
tion of weather dynamics become more difficult.
(3) Procedure of employment of the radio navigation means in flying by night
is basically the same as by day. But when using the ADF account for
night effect which may cause errors as high as 10 to 15°. The sign and
magnitude of the error vary continuously and cannot be determined in
advance.
(4) The locator beacons are free from night effects. Therefore it is advisable
to use them in night flying for checking the on-course condition and flying
the helicopter to approach the destination aerodrome.
(5) In night flight the crew is recommended to devote much time to visual orien-
tation and use various types of navigation computers as rare as possible.
(6) Successful fulfilment of a flight mission depends to great extent on the
crew's skill in fast and accurate mental dead reckoning and performance
of sight estimation.
(7) It is advisable to select course so as it has less possible number of turns,
adequate number of characteristic illuminated reference objects or r§fer-
ence objects which are well visible in the given weather conditions and at
actual altitude, and radio navigation aids available.
(8) On studying the route bear in mind characteristic features of the illu-
minated and natural reference objects and clarify the possibility of their
identification at a given altitude and visibility. The landing field (target)
area should be studied particularly thoroughly.
(9) Before flight calculate the flight data considering the reported wind, func-
tionally check the flight and navigation equipment and the cabin lighting.
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