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About the function of preselect HDG on A320

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About the function of preselect HDG on A320

Old 20th Jul 2023, 08:12
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About the function of preselect HDG on A320

Hi, everyone
The PDC told us to fly hdg 248° when airborne AND we tuned 248° in HDG window. The departure rwy heading is 263……
Question is: when we airborned , PULL the HDG and FMA showed TRK in HDG-VS FD mode??
How could this happened ?Bug or normal?
As I found on FCOM it should be in HDG mode……
leffsu is offline  
Old 20th Jul 2023, 10:55
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Originally Posted by leffsu
Hi, everyone
The PDC told us to fly hdg 248° when airborne AND we tuned 248° in HDG window. The departure rwy heading is 263……
Question is: when we airborned , PULL the HDG and FMA showed TRK in HDG-VS FD mode??
How could this happened ?Bug or normal?
As I found on FCOM it should be in HDG mode……
From the FCOM:

”HDG/TRK PRESET


GENERAL The system has a HDG/TRK preset function for takeoff and go-around. If the flight crew decides not to fly the flight plan after takeoff or go-around, the flight crew can turn the HDG/TRK knob on the FCU to preset a heading or a track. The set value remains displayed in the FCU HDG/TRK window until the flight crew pulls the knob.

AT TAKEOFF If the flight crew presets the HDG/TRK before takeoff and up to 30 ft RA, NAV disarms. The preset value remains displayed in the HDG/TRK window (even when RWY TRK engages at 50 ft RA). When the flight crew pulls the HDG/TRK knob (at least 5 s after liftoff), HDG or TRK mode engages. The aircraft follows the preset target.”

If You have acted as per above, You should have gotten HDG displayed once pulled.
Have You tried recycling the FPV pushbutton?
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Old 20th Jul 2023, 12:00
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Actually……NO
I am sure the FD is in HDG-VS mode
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Old 20th Jul 2023, 12:53
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Was it really TRK and not RWY TRK ?
Is it possible you 'failed' to pull or dit it before 5s after liftoff and you happened to pass 50ft at the same time engaging RWY TRK that you mistook it for a consequence of you pulling HDG ?
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Old 20th Jul 2023, 13:35
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Originally Posted by Meikleour
Should have PUSHED for heading!
Pushed? Maybe pull for heading
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Old 20th Jul 2023, 13:46
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when airborne,it always show RWY TRK……then I pull the know……TRK came out!
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Old 20th Jul 2023, 14:13
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Actually with HDG preselected you should get RWY as lateral mode in FMA (if LOC signal valid) until 50ft then FMA change with RWY TRK.

But if you got TRK then I really have no idea.
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Old 20th Jul 2023, 14:15
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same to me……Thats pretty weird.
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Old 20th Jul 2023, 16:10
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What should happen is straight forward. When lined up on the runway if you set a heading may be even RW heading after getting airborne it will change to RW TRK and at ACC ALT change to OP CLB. When you pull heading it will change to heading turn to preset heading.
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Old 20th Jul 2023, 16:17
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Do it again, and let us know.
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Old 26th Jul 2023, 14:16
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Somebody must have hit the HDG/TRK button by mistake or accident. It happens.
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