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Originally Posted by Blueskymine
(Post 10536124)
The RTA is okay for giving you an indication of what’s required without letting it do the job. However it’ll bring you right back to green dot if you let it take over which sometimes isn’t appropriate. Especially in a smaller airbus with higher wing loading. Not so critical in the bigger ones. I use the RTA with a selected speed to initially see what it will require in the cruise. Then I’ll select that plus 10 knots and work the rest out with descent speeds. It it really is a piece of cake. If you can’t make the time at this point, you advise ATC and they give you vectors. Or you drop to a lower level and slow up. Green dot is a knot higher for every 1000 feet over 20. So you can get some good speed reductions down low. Especially east bound out of the jet. Anyway, stick with it son. Just let the automatics do their job, and then when it can’t, intervene |
You can do it if you want. But when you’re up high at green dot with less than 10 knots to VLS and she’s a bit choppy - I’m paid to keep it on the rails and provide a safe margin. Not to reduce those margins and let the automatics take care of it.
The bus is a handful when she comes back with a ‘cannot’ and hands it over to you. I hope you’re ready for it. I’ll be down low at green dot plus 10 with my feet up reading the...notams. |
the Honeywell FMS that’s standard in most Australian buses will give you an estimate based on the current conditions to the second in which you will pass overhead the feeder fix. When you say "buses" do you mean Airbus aircraft? The limited number of FMSs I have experience on show an estimate time over the waypoint to the minute - and that "minute" is actually (sensibly) based on the half-minute: ie if the actual waypoint crossing time is 12:05:29(secs) it would show a crossing time of 12:05 - if the actual crossing time is 12:05:31(secs), it would should a crossing time of 12:06. This is NOT utilising an RTA feature, however - which I don't have in the FMS installed on the aircraft I fly. Makes the "30 secs early, but not late" thingy difficult without doing it manually. Perhaps some FMSs display an estimated crossing time to the second? Out of interest, are ATCer's aware of these limitations? |
You can put an RTA in seconds as well. personally this is my process. insert time marker 1. CI=0 (MRc) 2. Lower descent speed towards green dot. Note: only go the Green Dot + 20 to allow for a slower descent speed to be selected on descent if winds are not as forecast unless you have an up to date wind link on ACARS. if no luck 3. Set RTA to the assigned time minus 15 sec ( -30 sec/+0 requirement average) if it targets green dot pull green dot +10 when above 25000’ (G loading on Alpha prot settles around this altitude and below) 4. Look at the extra track miles required to make the time (distance between RTA and time market) and how long I have to do it. 5. Descend to a new cruise altitude, allowing average 5 Kt TAS plus 1 knot green dot reduction reduction per 1000, approx. Eg. Nil wind, Required crossing time of 2130 difference between waypoint and RTA is 8 nm after points 1-3. present time is 2100. 30min to lose 8 nm, or 16nm over 60 min, therefore 16 kts. 16/6 kts per 1000’ is about a 3000’ reduction in altitude. hemispherical = descend 4000’ insert new cruise alt if required on the PROG page Check/reinsert descent speed. RTA should do the rest. |
Originally Posted by ROH111
(Post 10535766)
I can’t help but ask F100 drivers and tonight I’ll include the Network A320 drivers, what the story is with their lack of ability to reach Beverly or Julim, on time. Forever in a day we fly into perth, reach the fix (up to 30 seconds early, but not late) do our 250 knots then get told to vector off to rejoin final, yep, behind an F100. Tonight we had speed cancelled and a time to make Beverly, made it fine, then got told to slow down, vector off but this time, it was behind a Network A320.... who earlier was given direct to Rolob as ATC could see they had no idea of space or time. I know it’s not just me who suffers this daily, is it lack of technology on the F100 that makes it difficult? Can you guys uplink the latest winds prior to decent? Curious to know what it is, it’s becoming frustrating. |
Originally Posted by josephfeatherweight
(Post 10536136)
No such luck for me - have approached the FMS manufacturer for answers and they have not been forthcoming. Would like to know how to achieve over a waypoint to the second?
When you say "buses" do you mean Airbus aircraft? The limited number of FMSs I have experience on show an estimate time over the waypoint to the minute - and that "minute" is actually (sensibly) based on the half-minute: ie if the actual waypoint crossing time is 12:05:29(secs) it would show a crossing time of 12:05 - if the actual crossing time is 12:05:31(secs), it would should a crossing time of 12:06. This is NOT utilising an RTA feature, however - which I don't have in the FMS installed on the aircraft I fly. Makes the "30 secs early, but not late" thingy difficult without doing it manually. Perhaps some FMSs display an estimated crossing time to the second? Out of interest, are ATCer's aware of these limitations? When you go to the RTA prompt at a waypoint it will give you the current estimate to the second. The flight plan page only gives you to the minute based on your above observations. So does a time marker. I personally use a time marker and cross check the estimate at the RTA page. Then you can see the trend and stoke the boilers or save the planet. |
Ah, I see, thanks for the explanation! Look forward to flying something with the RTA function!
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On a bus, time marker, pull speed, adjust and cross to the second. Too easy
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I don't see how a Netflix F100 can beat any other jet to JULIM at cost index zero :rolleyes:
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RTA’s can be met to the second in a Boeing. As maggot states, I believe it can be done in an airbus too. Simple remedy, if you consistently miss the times “turn left heading 090, we will fit you in when we can.” A few instances of this and the problem should be solved. I too drag my arse in behind fokkers as well. Very painful, it’s not that hard. |
Having flown both types I am pretty confident in easily achieving a fix time +/- 5 seconds or so. I don’t have to, of course, but I choose to out of respect for my fellow airmen and the long suffering controllers. That ATC has subscribed to the odd notion of central control is not the controllers’ fault, nor ours. It would be so much easier if a metering fix crossing time was part of our initial clearance. Why, pray tell, does ATC waste resources trying to predict crossing times when they could simply assign them hours prior, and let punitive holding be the wages of sin (or poor nav skills)? |
Originally Posted by morno
(Post 10536133)
It’s not going to drop out of the sky. Just let the automatics do their job, and then when it can’t, intervene. |
Originally Posted by Australopithecus
(Post 10536311)
That ATC has subscribed to the odd notion of central control is not the controllers’ fault, nor ours. It would be so much easier if a metering fix crossing time was part of our initial clearance. Why, pray tell, does ATC waste resources trying to predict crossing times when they could simply assign them hours prior, and let punitive holding be the wages of sin (or poor nav skills)? |
Time marker on BOTH Airbus and Boeing, open speed window and drive to the marker. Sorry I don’t understand the issue here......I plead ignorance regards other types |
What is especially frustrating is flying across the Bight at max chickens for 3.5 hours to then be required to “reduce speed to cross BVRLY at XX” - we’ve got ADSB/CPDLC - you can see where we are and what we’re doing... I fly what would be considered a modern aircraft and the FMS has no function to readily assist with achieving these requirements - in fact, it actually throws you under the bus because the FMS displayed estimated time over a waypoint is usually about 3-4 mins later than the time you actually end up flying over it - the discrepancy appears to magically fix itself when you’ve got about 3-4 mins to run and no chance to fix it. |
Originally Posted by neville_nobody
(Post 10536343)
I have been told that the current ATC technology is unable to do this and has to wait until everybody is closer in. Maybe someone in ATC could elaborate?
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Originally Posted by neville_nobody
(Post 10536343)
I have been told that the current ATC technology is unable to do this and has to wait until everybody is closer in. Maybe someone in ATC could elaborate?
That holding was either due to crazy winds, Speedbird Concorde descending on vapours or other random unpredictable furballs being coughed up by the system. |
Capn Bloggs - I thought we were mates!? I think you’ve got the wrong end of the stick there, I didn’t say anything about other aircraft “clearing out of my way”, did I? I just think the system could be better than watching a whole bunch of aircraft fly at high (planned) fuel flows/speeds across the country, and then be slowed to min speed approaching a waypoint, instead of sequencing the whole process earlier in the piece. I’m not all that swept up on the ATC system, so maybe it’s a pipe dream. As for blaming a system for my inadequacies, I don’t really think I did that either - can you re-read my post and perhaps clarify where I got you all hot and bothered? |
in fact, it actually throws you under the bus because the FMS displayed estimated time over a waypoint is usually about 3-4 mins later than the time you actually end up flying over it |
A what???.... |
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