This is not a query on the PMDG product JS41, as it is, in its own nature, a simply perfect simulation jewell. My question is on the real life FD system designed for this aircraft and many others. Why not select ALT SEL automatically whenever the pilot change the altitude selector?

 

Maybe there is a logic behind the action in this FD electronic innards, but I cannot think why not turn ALT SEL on automatically. Is there a reason for a pilot who changes the ALT to 3000 and apply a VS any other than go to 3000?

 

Regards,

 

Heron

The only thing I can think off is in the case that you are assigned a lower level for descent with a "when ready/at pilots discretion" instruction, setting the altitude selector to an altitude below you with it automatically ALT SEL would start a descent at the default VS for the autopilot system.

 

Another reason could be when on the approach and re-setting the missed approach altitude, however I believe most autopilot systems have an ALT-ARM inhibt system when the APP is armed/active.

 

On the Q400, ALT SEL is still there because a common rating is shared between the two in some airlines - Therefore some cross-similiarities had to be maintained. Why the JS41 has it, I have no idea.

Hi White,

 

Great to hear that, ideas which I did not pay a thought. I am not still at home in the incredible JS41 cockpit (you have to work there!!) after so many years driving almost intelligent crafts. Most of the flights I have been using ALT SEL correctly, but other times I forgot to press it and had a hard time. That's the reason of my questioning.

 

Regards,

 

Heron

 but other times I forgot to press it and had a hard time.

Believe me, you are not the only one. I have seen a few YouTube videos of simmers which have forgot and violated/busted their assigned level :good:

It's the same on the DHC8. We have to confirm that "Alt Sel" is selected after changing the assigned level.

 

Depends on the situation as to whether it's required. For instance during a GNSS RNAV approach, it isn't selected when we change the assigned level to the missed approach altitude. This is because if we press "Alt Sel", it will attempt to level out at that level rather than contine down to the MDA. (if we are higher than the missed approach alt).

 

Very easily forgotten and I've seen many pilots press it when it's already selected, in which case it cancels the alt capture and if the crew isn't paying attention.... straight though the assigned level.

Done it plenty of times on Vatsim, both in the JS41 and Q400. If you're lucky you catch it as you hear the 1000ft to go.

Being filed for FL200 and finding yourself being asked by ATC to confirm your altitude as you pass 23800ft on climb isn't fun

 

I usually have better results saying aloud "(Altitude) set and selected" helps me remember. This is slightly different to my jet procedure of saying "(Altitude) Set".

 

The extra ".., set and selected" as you visually confirm it is armed is just one extra protection.

 

Every time I get lazy and stop talking in the cockpit, I'm gonna start missing little things like this. Being embarrassed on Vatsim is enough...

I'v heard of real world incidents with altitude busts in turboprop aircraft which may be related... Fortunatley real world operators are likely to have 2 in the cockpit to catch the error.

Thank you all for the replies. One thing is true, discipline and loud calls in the cockpit are imperative.

 

I forgot about the Missed Approach procedures - yeah, a fundamental reason to NOT arm the ALT SEL.

 

And yes, a copilot helps a lot...

 

Regards,

 

Heron