TOD activation (bus question)?
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TOD activation (bus question)?
on the Bus 320, when do you push "alt"?
how many miles before the TOD?
how many miles before the TOD?
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I'm guessing from the question that you're not a commercial pilot so, do you mean on an RNAV STAR or for a normal descent profile?
The aircraft will not just descend, unless you have told it to. ATC have no idea where your profile ToD is and generally (in Europe anyway) you're restricted by STAR levels and speeds so you have to deviate from the "ideal" profile.
If normal profile then once cleared to descend you can push Alt for a managed descent or pull for open descent.
On an RNAV profile it's a little less straightforward depending on where you are and what you're cleared to do.
The aircraft will not just descend, unless you have told it to. ATC have no idea where your profile ToD is and generally (in Europe anyway) you're restricted by STAR levels and speeds so you have to deviate from the "ideal" profile.
If normal profile then once cleared to descend you can push Alt for a managed descent or pull for open descent.
On an RNAV profile it's a little less straightforward depending on where you are and what you're cleared to do.
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Hi,
To the best of my knowledge, we usually do it about 8-10nm before TOD for the A/P to gradually "ease" into DES phase, if we are on VNAV.
If ALT is pushed AT TOD, the a/p will command a "drastic" change of pitch, which is relatively uncomfortable to everybody.
Any comments?
Happy Easter,
Lion-g
To the best of my knowledge, we usually do it about 8-10nm before TOD for the A/P to gradually "ease" into DES phase, if we are on VNAV.
If ALT is pushed AT TOD, the a/p will command a "drastic" change of pitch, which is relatively uncomfortable to everybody.
Any comments?
Happy Easter,
Lion-g
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For a managed descent, push at a mile to go and all works out OK. Any later and the aircraft tends to "dive" and earlier the aircraft descends at 1000fpm until profile intercept.
20 miles past the TOD and pull THR IDLE / OPEN DES, then the thrust really is at idle, and normally you still end up on profile round about 10000ft. If not you can play a little with selected speed.
I personally find the DES mode pretty conservative since it takes use of engine anti-ice etc in to account, therefore on a nice sunny day if you really want an idle descent, I prefer the aforementioned.
I personally find the DES mode pretty conservative since it takes use of engine anti-ice etc in to account, therefore on a nice sunny day if you really want an idle descent, I prefer the aforementioned.
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Agree with the above, prefer open descent - to start with anyway - as the thrust reduction and pitch change will be more gentle. I usually leave it until 5-10 miles passed TOD.
Managed descent is too shallow high up, and the efforts to stay on profile are a little too enthusiastic for my liking.
S.
Managed descent is too shallow high up, and the efforts to stay on profile are a little too enthusiastic for my liking.
S.
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The company I work for has changed the idle factor to ensure a slightly later descent around 3.5:1 profile. As some of you say it's a shallow profile at 0.0, making it nearly a 4:1 profile.
