Instrument Flight
Flight Procedures
Maintaining an Arc Around a Station
Two ways of maintaining an arc
around a station are the chord
method and the angle of bank
method. Either procedure (or a
combination of the two) will work
at any distance from a station.
However, the chord method is
generally more practical when
you’re flying a distant arc (usually
more than 12 DME from a
station), while the angle of bank
5
method usually works better
5
when you’re flying an arc close in
(12 DME or less). The chord
C.
method consists of a series of
short straight legs, connected by
29 nm arc
turns. The angle of bank method
is flown as a shallow turn with
C
Correct 5-10 degrees for each
1/2 mile deviation from arc
variable AOB to maintain a
constant arc.
10
Chord Method
B.
(Normally used for arcs of
Desired
greater than 12 DME) To
10
30 nm arc
maintain an arc using the chord
A.
method, fly a series of short,
straight legs connected by small
turns that take you slightly inside
and outside the actual arc
(Figure 22). To use the chord
31 nm arc
method: first, ensure that the
station is tuned and identified;
then determine direction of turn
and calculate lead point. Initiate
the turn at the lead point (when
Vary the amount of
DME equals radius of arc, plus or
correction according
to the rate of deviation
minus the LPC) using a 1/2 SRT.
and adjust as
Roll out from your interception
necessary according
to the rate of
turn when the bearing pointer is
correction
5-10 degrees ahead of the
90-degree benchmark at the
correct DME. Maintain your
heading until the bearing pointer
has moved to 5-10 degrees
behind the 90-degree benchmark
and then turn until the bearing
pointer is once again positioned
5-10 degrees ahead of the
90-degree benchmark.
A
Figure 22: MAINTAINING AN ARC (CHORD METHOD)
Page 73
(4-01) Original
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