Descent management is hard

[twinotterifr]

line training on a320, descent management is challenging, its the only thing im not fully confident with yet boo hoo :-C

[redsnail]

Where is it not working for you? I don't fly the A320, but my rule of thumb is 3 x the flight level as the start point, adjusted for wind. Eg, if at FL400, the latest I should be descending is 120 nm (3 x 40). Obviously, the FMS will have a 3 deg TOD point in it depending on the first constraint on the arrival. You can use this rule of thumb to help visualise if you're high or low.
My husband does fly the A320 and he has commented a few new guys get the speed way back to something like 220kt at 30 nm which then annoys the controllers and can upset the profile. Speed brakes aren't very effective when you're slow.
Checkboard You might be able to help here.

[rudestuff]

Doesn't it do that for you? Boeing gives you a pink string and a ToD point...

[Checkboard]

Yes - your three times table is a good guide. If you're not great with mental arithmetic though, memorising a couple of descent gates works pretty much as well:

270 knots, 9000 feet, 30 miles
250 knots, 5000 feet, 20 miles
180 knots, 3000 feet 10 miles

And yes, the problem I see the most in new pilots is a fear of being too fast, and then being rushed into the approach. They tend to over-correct for that, and want to slow down to, say 220 knots at 20 miles or more. Now this is much closer to an efficient glide speed (green dot) than 250 knots is, at 220 knots the aircraft isn't washing off energy in parasite drag the way it would be at 250 knots ...so the aircraft drifts high on the approach path. Now the pilot has TWO problems to deal with - getting back onto the approach path AND dealing with their excess energy.

It is far better to be fast, and on the approach path, than it is to be high and on speed. If you are fast and you can intercept an ILS glide path (or stay in VNAV) then the aircraft autopilot will keep you on the correct slope, and you ONLY have to deal with the speed - and that's easy. Put the gear down, if you need it. You can easliy be 220 knots at 10 miles, on glide path (or 210 at 9 miles, 200 at 8 miles, 190 at 7 miles, 180 at six miles) and putting the gear down will have you stable at 1000 feet.

In setting up for the approach (deciding when to slow down) the aircraft (WITHOUT touching speed brakes) will slow down in Open Descent 10 knots every 1 mile, and will do that in 2/3 rds the distance if you are level. Say you are on vectors, level at 5000 feet on downwind at 250 kts. You know the controller will turn you onto base at ten miles for the ILS, when do you have to slow for that? Well if you want to be 220kts turning base, then you know you'll only take (250 kts - 220 kts =) 3 miles to lose that speed if you are in open descent, and 2 miles if you are level. You can keep that 250 kts to about 5 miles past the field, select 220 and you'll be at 220 for the base turn, take Flap One and 180 kts turning base an you'll slow to 180 and descend to 3000' for the ILS on base no problems - and that's without going for speedbrake or gear which is always available if you get turned early or run into a tailwind on base or approach.

Good luck with it all. It comes in time.

[Speed_Trim_Fail]

And yes, the problem I see the most in new pilots is a fear of being too fast, and then being rushed into the approach. They tend to over-correct for that, and want to slow down to, say 220 knots at 20 miles or more. Now this is much closer to an efficient glide speed (green dot) than 250 knots is, at 220 knots the aircraft isn't washing off energy in parasite drag the way it would be at 250 knots ...so the aircraft drifts high on the approach path. Now the pilot has TWO problems to deal with - getting back onto the approach path AND dealing with their excess energy.


If you remember nothing else (other than your 3x table), remember this, which is fantastic advice. Keep the aircraft at 250/240kts until 15-17 miles and you will be a good place. Not least as this is what the aircraft would do itself if it flew fully managed, and is what the descent profile is based on.

As ever your company manuals and the FCTM should be a good guide too.

[twinotterifr]

i understand it now, my biggest issue wasn't the altitude/distance calculation, more so the lack of situational awareness, i was getting overwhelmed by the descent itself being inexperienced and not making use of all the functions available to my advantage. I will list down everything that i have improved on since:

-Using traffic cues to predict the arrival
-anticipating shortcuts and using the DIR to TEMP function on FMGS to indicate track miles
-asking ATC how many track miles remaining on the intermediate approach to help my judgement
-using the ND rings to further support visually the amount of miles to a waypoint
-making full use of SPD/ALT constraint inputs on the FMGS to optimize the descent profile
-clearing the SPD/ALT constraints on the F-PLN based on ATC instructions
-updating the managed speed on PERF des page to recalculate the profile
-constantly calculating if the aircraft is high/low on profile between each waypoint rather than the referencing the total track miles only
-configurating the aircraft based on speed control on the approach rather than completely following SOP config distances (3:1 / 6:3:1)
-utilizing open des and V/S properly based on the profile
-better understanding of the theory when decelerating/accelerating, idle/geometric segments, managed/selected modes and applying them in the dynamic situations
-utilizing CRM and requesting the captain to conduct PM duties rather than to get intimidated and try to manage everything as the PF

well aware that this may seem very novice/amateur-ish to alot of people out there but these were the issues i was experiencing being new to the line, and maybe it could help out a brand new trainee out there in the slight chance

[Michael S]

i understand it now, my biggest issue wasn't the altitude/distance calculation, more so the lack of situational awareness, i was getting overwhelmed by the descent itself being inexperienced and not making use of all the functions available to my advantage. I will list down everything that i have improved on since:

-Using traffic cues to predict the arrival
-anticipating shortcuts and using the DIR to TEMP function on FMGS to indicate track miles
-asking ATC how many track miles remaining on the intermediate approach to help my judgement
-using the ND rings to further support visually the amount of miles to a waypoint
-making full use of SPD/ALT constraint inputs on the FMGS to optimize the descent profile
-clearing the SPD/ALT constraints on the F-PLN based on ATC instructions
-updating the managed speed on PERF des page to recalculate the profile
-constantly calculating if the aircraft is high/low on profile between each waypoint rather than the referencing the total track miles only
-configurating the aircraft based on speed control on the approach rather than completely following SOP config distances (3:1 / 6:3:1)
-utilizing open des and V/S properly based on the profile
-better understanding of the theory when decelerating/accelerating, idle/geometric segments, managed/selected modes and applying them in the dynamic situations
-utilizing CRM and requesting the captain to conduct PM duties rather than to get intimidated and try to manage everything as the PF

well aware that this may seem very novice/amateur-ish to alot of people out there but these were the issues i was experiencing being new to the line, and maybe it could help out a brand new trainee out there in the slight chance

Actually, to my eye, it looks very mature.