[HELP] Helicopter Flight Path Problem

Okay, here's a video explaining my problem as to what goes wrong during the flight path for helicopters.

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"target" "heli_spot_1"
"targetname" "heli_start"
"classname" "script_origin"
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"origin" "-8884 -157 2150"
"target" "heli_spot_1"
"targetname" "heli_start"
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"origin" "-224 -130 2150"
"targetname" "heli_spot_1"
"target" "heli_spot_2"
"classname" "script_origin"
"_color" ".5 1 1"
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"angles" "0 275 0"
"origin" "-130 1923 2150"
"targetname" "heli_spot_2"
"target" "heli_spot_3"
"classname" "script_origin"
"_color" ".5 1 1"
}
{
"angles" "0 275 0"
"origin" "-2445 2306 2150"
"targetname" "heli_spot_3"
"target" "heli_spot_4"
"classname" "script_origin"
"_color" ".5 1 1"
}
{
"angles" "0 275 0"
"origin" "-1950 -1666 2150"
"targetname" "heli_spot_4"
"target" "heli_spot_5"
"classname" "script_origin"
"_color" ".5 1 1"
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{
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"targetname" "heli_spot_5"
"target" "heli_spot_6
"classname" "script_origin"
"_color" ".5 1 1"
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"targetname" "heli_spot_6"
"target" "heli_spot_7"
"classname" "script_origin"
"_color" ".5 1 1"
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{
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"origin" "1441 426 2150"
"targetname" "heli_spot_7"
"target" "heli_spot_8"
"classname" "script_origin"
"_color" ".5 1 1"
}
{
"target" "heli_spot_8"
"origin" "529 474 2150"
"targetname" "heli_loop_start"
"_color" ".5 1 1"
"angles" "0 270 0"
"classname" "script_origin"
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"targetname" "heli_leave"
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"targetname" "heli_leave"
"classname" "script_origin"
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"angles" "0 270 0"
"origin" "-10430 2909 2100"
"targetname" "heli_leave"
"classname" "script_origin"
}
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"angles" "0 270 0"
"origin" "-10400 -3170 2000"
"targetname" "heli_leave"
"classname" "script_origin"
}
{
"angles" "0 255 0"
"target" "heli_crash_end"
"origin" "266 -460 1945"
"targetname" "heli_crash_start"
"classname" "script_origin"
}
{
"targetname" "heli_crash_end"
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"_color" "0 1 .5"
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}