Managed descent, altitude constraints, radar headings
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Is it common that the autoflight system will not comply with altitude constraints?
I’m just curious, I never flew Boeing, I would love to tho! On A320 no such restrictions, we always set the lowest altitude and it will comply with the altitude constraints. At least from my experience I never saw it failing to do so.
I’m just curious, I never flew Boeing, I would love to tho! On A320 no such restrictions, we always set the lowest altitude and it will comply with the altitude constraints. At least from my experience I never saw it failing to do so.
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It's down to the operator and we can set the lowest altitude. The FCTM calls it alternate MCP altitude setting technique. Just make sure to always remain in VNAV PTH or VNAV SPD.
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pineteam
No, I can't say I've seen any SRs about aircraft not respecting the VNAV constraints. I personally don't agree with the procedure, it adds workload and the potential for unwanted level-offs. Boeing only recommends the alternate procedure (setting the highest/lowest altitude) for closely spaced constraints. It's one of those "thats what the book says" things I guess.
No, I can't say I've seen any SRs about aircraft not respecting the VNAV constraints. I personally don't agree with the procedure, it adds workload and the potential for unwanted level-offs. Boeing only recommends the alternate procedure (setting the highest/lowest altitude) for closely spaced constraints. It's one of those "thats what the book says" things I guess.
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Mistrust of automation is definitely more common amongst Boeing pilots. Historically speaking, quite understandable. Though Boeing have tried on the 787, seems type chiefs are just not interested in changing their old ways. Fly it like a tractor you will!
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Setting intermediate altitudes is a pain but its not because of distrust of automation.
Its about commonality of procedures across all approach types.
So long as non-precision approaches exist there is a place for a conservative approach.
Where I operate part of the problem has been ATC unwillingness to fully embrace RNP AR approaches.
When they were first introduced in OZ they had minima of 200’ !
They were trashed because to many operators wouldn’t or couldn’t use them and different types had different minima and increased ATC workload to apparently unacceptable levels.
Solution ? Get rid of them.
Plus ATC likes to keep the option of taking you off an approach on a heading.
Out of VNAV.
Setting intermediate altitude is cheap insurance.
Its about commonality of procedures across all approach types.
So long as non-precision approaches exist there is a place for a conservative approach.
Where I operate part of the problem has been ATC unwillingness to fully embrace RNP AR approaches.
When they were first introduced in OZ they had minima of 200’ !
They were trashed because to many operators wouldn’t or couldn’t use them and different types had different minima and increased ATC workload to apparently unacceptable levels.
Solution ? Get rid of them.
Plus ATC likes to keep the option of taking you off an approach on a heading.
Out of VNAV.
Setting intermediate altitude is cheap insurance.
Last edited by TukwillaFlyboy; 16th Jun 2021 at 07:12.
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FlightDetent
As it turns out, I had the chance to do a fully managed arrival today. With the speed managed, I got all the way to F2, then saw it was going to slow to ~160kt about 8nm from the runway. I guess it'd have been fine today, but in a normal traffic situation, it would have just messed up the approach controller's day.
It's a clever system, and I like it, but it isn't very practical for day to day use.
As it turns out, I had the chance to do a fully managed arrival today. With the speed managed, I got all the way to F2, then saw it was going to slow to ~160kt about 8nm from the runway. I guess it'd have been fine today, but in a normal traffic situation, it would have just messed up the approach controller's day.
It's a clever system, and I like it, but it isn't very practical for day to day use.
Only half a speed-brake
I'd be interested to see which approach and arrival it was, PMs accepted..
The best description I have is it's not up to the task of achieving a meaningful speed reduction schedule. All winds and ISA dev typed in, etc etc...
The best description I have is it's not up to the task of achieving a meaningful speed reduction schedule. All winds and ISA dev typed in, etc etc...
Check Airman
This is my experience too, once F2 selected the speed drops too low, on some approaches that is the time I’ll select 160-180kts to avoid upsetting ATC. Some of the approach allow you select F2 later, or have 160kt restrictions further out, so it all works well. YBCG 14X, YBSU 13W
I think it does a great job, and it makes life very simple especially in marginal weather.
This is my experience too, once F2 selected the speed drops too low, on some approaches that is the time I’ll select 160-180kts to avoid upsetting ATC. Some of the approach allow you select F2 later, or have 160kt restrictions further out, so it all works well. YBCG 14X, YBSU 13W
I think it does a great job, and it makes life very simple especially in marginal weather.
