Energy management during approach - how do You monitor it?

[Stochastyczny]

Hello guys,
It's my first post here.

I'm preparing short presentation (for university) about energy management during approach,
I'd like to ask You some questions about Your method of maintaining correct vertical path and speed during approach.

Any kind of answer will be appreciated, I'll present it in points, but you can answer whatever you like.
I'm flying B737-800, so my question might be biased by that. Still, if you could explain methods of planning descend/approach on other types, I would also very much appreciate that.

1. What is your primary method of monitoring descend profile?
2. Do you use any other methods in parallel to check your calculations? How often do you verify your descend profile?
3. How often do you use VNAV during descent/approach? How often do you have to change A/P modes during descent/approach?
4. What is your "philosophy" on using speedbrakes?
5. RNAV app: How often you had to make automation workarounds during RNAV approach to satisfy ATC instructions?
6. Have you ever had to make a decision to go-around due to high energy approach?
7. Have you ever had to make a decision to go-around due to VNAV function/automation behavior?

I'm mostly interested in first two questions, which I want to use in my presentation (to show different methods), but any elaboration would be appreciated.
Thanks in advance!

[Bergerie1]

This might help:- https://www.skybrary.aero/index.php/Energy_Management_during_Approach

[Sleeve Wing]

1. Dead reckoning. Height against distance to STAR altitude. Regular checks because of wind speed differences with altitude. Also makes sure you can get the Cabin Pressure down within descent limits.
2. Deceleration times with regard to pattern limiting speeds. Regular checks of distance to runway threshold.
3. All the time. Use A/P to help, not to dictate your actions.
4. DON'T USE THEM unless ATC cause a change in your profile and you need a rapid adjustment. Costs fuel.
5. Few. You should anticipate changes using overall height/ distance to runway threshold, by being familiar with the requirements of destination ATC.
6. Once or twice, when given late descent because of traffic ahead. You won't get into this situation if you think "outside the box". Maybe slow down earlier ?
7. No. I would probably go manual and adjust power to suit, following the Flight Director, but this is probably against today's philosophy !

[+TSRA]

1. Mental calculation between current and next charted altitude using a 3-degree slope with corrections for wind against the FMS calculated crossing altitudes. Works like a charm.

2. No other methods, but I verify every few thousand feet, maybe a little more frequently in mountainous terrain.

3. VNAV is used during all descents except for immediate ATC requests. We're a RNP-AR heavy airline, so we don't routinely have to change AP modes during descent or approach - we're generally coupled from TOD to landing. When there is no STAR, distance-from-airport gates are programmed (e.g. 3,000'+field elevation at 10 miles back of airport or MSA 25 back, depending on terrain and conditions).

4. I only use speedbrakes or the props (when flying turbo-props) when ATC required a help with spacing. Otherwise, I'd manage the energy so as to avoid putting out the brakes.

5. We never modify an approach in the FMS for ATC requests because it corrupts our database. SID and STAR requests will get programmed if there is time, but mostly ATC requests are handled through the FGCP.

6. A few times while doing line indoc and maybe once or twice during line ops. It happens, but the easiest thing to do is not to get in that position in the first place. An extra minute in the downwind or slowing an extra few miles sooner makes all the difference. Tell ATC what you need and they're usually accomodating.

7. A few times the pretty pink lines disappear, and we've gone around, but always when in IMC. If the autopilot stops working, no big deal - that's what we all got into this for in the first place, flying airplanes. When the flight director stops working and we're in VMC, the automatics come off, and again we kick it old school. I don't know why you'd go around on an otherwise stable approach with the airport in sight just because some information on a screen you're probably not supposed to be looking at anymore gave up the ghost.

[PEI_3721]

Use airbrake / speed-brake early to achieve or regain the required flight path. This does not use more fuel; - if you are already above the required path / speed profile (a reducing energy level), you have already expended the fuel energy - its lost. Thus the earlier that stable conditions can be achieved, maximising the time spent at the lowest ‘energy rate’ should equate to the final min fuel profile (aircraft / config / ATC dependent).
No airbrake does not save fuel, but use of airbrake might save face by avoiding an overrun.
Minimum fuel used is not minimum cost; that is achieved by avoiding the grass at the end of the runway.

Use ‘gate’ checkpoints to monitor the approach - slide 8; a mental model of how-goes-it, referenced from memory.
https://www.dropbox.com/s/o9jkpmtwrt86lxp/Managing%20threats%20and%20errors%20during%20Approach%20and% 20Landing%20Final.pdf?dl=0