Technical data

Product Specification
HIF-2121/R5 CAGE CODE: 97896 SCALE: NONE SIZE: A DWG NO: 965-1176-601 REV: D SHEET 81
When the roll angle exceeds these limits two “Bank Angle” voice messages are given with the standard 0.75 second delay
between messages. Once the bank angle messages are given the voice is shut off until the roll angle increased by another 20%
at which time another two bank angle messages will be given. If the radio altitude data is invalid (e.g., looses track at high
roll attitudes) then the warning threshold is set to the maximum curve value. Figure 6.4.4-1 illustrates the bank angle curves.
When the roll angle exceeds the curve for altitudes below 210 feet, the .75 second pause is not used, otherwise the two “Bank
Angle” voice messages are given with the standard 0.75 second delay between messages. Once the bank angle messages are
given, the voice is shut off and the bank angle curve is biased 20% to the right. Only if roll angle then violates this biased
curve will another two bank angle messages be given, at which point the bank angle curve will be biased another 20% of
nominal to the right. If the roll angle then violates the 40% biased curve, the bank angle messages become continuous with a 3
second pause between sets of messages. The following example illustrates the bank angle callout logic using the 50 degree
maximum curve value.
Conditions: (This example applies to a continuous roll past 72 degrees): Aircraft starts banking at cruise altitude. Nominal
bank angle threshold set to 50 degrees. As roll angle exceeds 50 +1/-2 degrees, “Bank Angle, Bank Angle” is given once and
the callout curve is biased up 20% to 60 degrees. Now as long as the roll angle remains less than 60 degrees no further
messages will be given. However, if the roll angle decreases below 50 degrees, and then increases greater than 50 degrees,
another “Bank Angle, Bank Angle” is issued and the callout threshold is set to 60 degrees.
If roll angle continues to increase past 60 +1/-2 degrees, “Bank Angle, Bank Angle” is given again and the callout curve will
be biased up another 20% of nominal to 72 degrees. Now as long as the roll angle remains less than 72 degrees no further
messages will be given. However, if the roll angle decreases below 50 degrees, and then increases greater than 50 degrees,
another “Bank Angle, Bank Angle” is issued and the alert threshold is set to 60 degrees.
If roll angle continues to increase past 72 +1/-2 degrees, the continuous voice message with a three second pause between
message pairs will start, “Bank Angle, Bank Angle” (3 sec pause) “Bank Angle, Bank Angle” (3 sec pause)..... and so on.
However, if the roll angle decreases below 72 degrees the messages will stop. As long as the roll angle remains less than 72
degrees no further messages will be given. If the roll angle then increases to greater than 72 degrees the continuous message
will start again. Only if the roll angle decreases below 50 degrees, and then increases greater than 50 degrees, will another
“Bank Angle, Bank Angle” be issued and the whole curve biasing logic will start over.
The above example shows the threshold biasing above 210 feet AGL. It is applicable to all altitudes AGL by replacing “50”
with the curve value for the current radio altitude. However, the sensitivity of the curve to radio altitude, and radio altitude
changes during banking, must be kept in mind when trying to predict the callout thresholds for low level flight.
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BANK ANGLE WARNING THRESHOLD (+/- DEG)
15 DEG
50 55
ADDITIONAL AUTOPILOT
ENGAGED WARNING AREA
WARNING AREA
210 FT
FIGURE 6.4.4-1: BANK ANGLE CURVE (TURBOPROP)