Fenix - Speed issue in Approach Mode

[MarkW]

Is there an issue with speed in Approach Mode on the Fenix?  Or is it user error.

So here is the situation.  On approach and Approach Mode active, ATC gives me a speed restriction of 190 knots, green dots is approx 210 knots and I have flaps 1 out.  Once established on approach and speed restriction cancelled, I lower to flaps 2 push the speed button to managed mode and the aircraft increases the throttle and speed jumps to 250 knots.  I think this is the speed of last waypoint before I manually entered the speed.  Why would it do this and not just go to Approach Mode speed at Flaps 2 ?

[Bobsk8]

32 minutes ago, MarkW said:

Is there an issue with speed in Approach Mode on the Fenix?  Or is it user error.

So here is the situation.  On approach and Approach Mode active, ATC gives me a speed restriction of 190 knots, green dots is approx 210 knots and I have flaps 1 out.  Once established on approach and speed restriction cancelled, I lower to flaps 2 push the speed button to managed mode and the aircraft increases the throttle and speed jumps to 250 knots.  I think this is the speed of last waypoint before I manually entered the speed.  Why would it do this and not just go to Approach Mode speed at Flaps 2 ?

Are you sure you are arming the approach mode on the MCDU performance.  Once I do that, and go to managed mode, the speed goes to around 180 with flaps 2.. 

[MarkW]

In this case I did not arm it but was past the D so it should have automatically changed to APP mode. 

[DescendDescend]

Pretty sure that if you pass  the D in selected speed the D will be in white and not magenta hence the FMGS Approach Phase will not arm automatically.

[SAS443]

17 minutes ago, MarkW said:

In this case I did not arm it but was past the D so it should have automatically changed to APP mode. 

Which color was the D? FMGS enters approach phase automatically only if it's in magenta. A white D requires manual activation afaik.

 

[Bobsk8]

 I always arm approach on the MCDU, I didn't know there was any other way. 

[MarkW]

18 minutes ago, SAS443 said:

Which color was the D? FMGS enters approach phase automatically only if it's in magenta. A white D requires manual activation afaik.

 

Good point I don’t recall but will check this next time. 

[Jeff Nielsen]

No, the FNX does have an un-commanded acceleration for some reason.  You should be able to leave it in managed then passing D it should decel and go in to APPR mode automatically, but it doesn't it, just goes full tilt.  I usually pull speed well before D, the activate APPR Phase in the MCDU, then go back to managed.  That's how I get around it.  

The plane has a mega balloon issue also that I can't seem to get around.  It doesn't help that the sim winds are all over the board., updating way too much.

[pcpilot58]

I may be having a similar issue though slightly different symptoms. I have done a couple of ILS approaches where I had set the speed manually to 160 knots to fly down the glideslope I was in APP mode so glideslope captured. I had set "Approach " in the MCDU and all the speeds for the approach were there. I then selected managed mode on the speed (button IN) VAPP was 137 knots the speed then jumped to 180 knots with no sign of decreasing. Further flap reduction had no impact so I had to go in and set the speed manually to 137 knots. I must admit I did not go back to the MCDU to see if somehow it had come out of approach mode. I will do some furher testing today to see if it is something I am doing it has happened a couple of times the last time on a crosswind landing which was at a320 limits.

[Fiorentoni]

6 hours ago, Jeff Nielsen said:

No, the FNX does have an un-commanded acceleration for some reason.  You should be able to leave it in managed then passing D it should decel and go in to APPR mode automatically, but it doesn't it, just goes full tilt.  I usually pull speed well before D, the activate APPR Phase in the MCDU, then go back to managed.  That's how I get around it.  

The plane has a mega balloon issue also that I can't seem to get around.  It doesn't help that the sim winds are all over the board., updating way too much.

What happens after you pushed managed after activating the APPR phase? Speed should go to green dot with no flaps out or to the  S/F speed with flaps 1/2. It doesn‘t for you? Do you have a speed restriction in the FMC after the IAF (shouldn‘t be, but you can enter one manually)? This would overwrite the greendot/SF-speeds commanded speeds in managed mode.

I‘ve not once had any problem on approaches with speed on the Fenix, not once. And I‘ve done all kind of approaches, from ILS to visual, on Vatsim with varying speed restrictions, with varying flaps, coming in with managed speed and automatic APPR phase or with selected speed and manual APPR phase… so unless you detected a very rare bug I‘d say it‘s some user error somewhere in between.

[Fiorentoni]

1 hour ago, pcpilot58 said:

I may be having a similar issue though slightly different symptoms. I have done a couple of ILS approaches where I had set the speed manually to 160 knots to fly down the glideslope I was in APP mode so glideslope captured. I had set "Approach " in the MCDU and all the speeds for the approach were there. I then selected managed mode on the speed (button IN) VAPP was 137 knots the speed then jumped to 180 knots with no sign of decreasing. Further flap reduction had no impact so I had to go in and set the speed manually to 137 knots. I must admit I did not go back to the MCDU to see if somehow it had come out of approach mode. I will do some furher testing today to see if it is something I am doing it has happened a couple of times the last time on a crosswind landing which was at a320 limits.

Was it exactly 180 knots or was it as S-Speed (which is mostly around 180 kts)? You did not say what flaps setting you were on. If you had set flaps 1 than that would be the correct behaviour, however it should consequently reduce speed to F-Speed when you set flaps 2.
What you described I have done dozens of times on Vatsim, that‘s pretty much standard on busy airports, and speed always went to the flaps commanded speed as soon as I pushed managed.
As with the poster above the only thing I can think of is some manual speed restriction set in the FMC for the approach waypoints. Do you do that ever?

[pcpilot58]

4 minutes ago, Fiorentoni said:

Was it exactly 180 knots or was it as S-Speed (which is mostly around 180 kts)? You did not say what flaps setting you were on. If you had set flaps 1 than that would be the correct behaviour, however it should consequently reduce speed to F-Speed when you set flaps 2.
What you described I have done dozens of times on Vatsim, that‘s pretty much standard on busy airports, and speed always went to the flaps commanded speed as soon as I pushed managed.
As with the poster above the only thing I can think of is some manual speed restriction set in the FMC for the approach waypoints. Do you do that ever?

I did not see S speed referenced and it was 180 knots I was on flaps 2. I am going to try to repeat the flight and see what happens more closely today.

[Fiorentoni]

9 minutes ago, pcpilot58 said:

I did not see S speed referenced and it was 180 knots I was on flaps 2. I am going to try to repeat the flight and see what happens more closely today.

Alright that‘s a pretty good indicator that the aircraft was not (anymore) in APPR phase, because it should always show S and F speeds in APPR phase. I think a manual speed restriction at some waypoint might cause this (even after entering APPR phase manually/automatically), but I‘m not 100% sure, because in real life it‘s prohibited to manually change any waypoint (speed, altitude etc.) after the IAF.
I can‘t think of many other things that would force the aircraft to leave/overwrite APPR phase, except for the obvious (doing a climb somewhere in between, entering a new CRZ level on the PROG page, going into TOGA detent etc.).

[pcpilot58]

15 minutes ago, Fiorentoni said:

Alright that‘s a pretty indicator that the aircraft was not APPR phase, because it should always show S and F speeds in APPR phase. I think a manual speed restriction at some waypoint might cause this (even after entering APPR phase manually/automatically), but I‘m not 100% sure, because in real life it‘s prohibited to manually change any waypoint (speed, altitude etc.) after the IAF.
I can‘t think of many other things that would force the aircraft to leave/overwrite APPR phase, except for the obvious (doing a climb somewhere in between, entering TOGA etc.).

It was a fairly chaotic approach weather wise, I approached with a crosswind that was above limits that slowly came into limits. It was fairly gusty as well with the plane  chasing the ILS.and the engine spooling up and then down. I took the autopilot out at 500 feet fully configured flaps full gear down.

[VBHB]

I rarely activate approch mode the MCDU as when I hit 10,000 I turn off speed manage mode and change the speed to 240kts or per ATC/STAR. I've never had that problem you described once. That's my way of flying other people do differently. I have found throughout the years bugs that pop up from time to time and I'm sitting there going "what the hell" when the plane is doing things it's not supposed to.