A310 exceeding red tape speed on initial climb after takeoff

[Malte Dietsch]

Hi,

I have noticed on several occoasions the following behaviour:

- After Takeoff, I engange A/THR, P. CLB and NAV and AP1

- Sometimes, the A310 continues accelerating past the calculated speed (250 IAS for example) and speeds of the 390 (!) knots

- It doesn't seem to stick to the calculated or manually set speed at all

- Workaround: I have to switch AP off and on again, turn off the the desired modes and turn them back on again

So I'm asking myself, what is going wrong here?

Thx

Malte

[Jehudale]

Looks like it is related to what I have posted 

 

Edited December 27, 2021 by Jehudale

[Malte Dietsch]

Oh yes that sound like the same issue.

Unfortunately, no solution?

So I will use my "workaround"...

[Jehudale]

To me that happened onlz on descends so far, when I used FLC before that. Than it sticks to the manual dialed speed instead of the FMS speed, mostlz because teh selected speed is in mach and it wants to hunt that at lower levels. Mz workaround in that case is to go FLC, dial in a slow speed until it gets to knots instead of Mach, dial it up again to 270 and re/engage profile mode. That helped always. It never heppened to me after takeoff as far as I can remember.

[Max]

On 12/27/2021 at 5:15 PM, Malte Dietsch said:

Hi,

I have noticed on several occoasions the following behaviour:

- After Takeoff, I engange A/THR, P. CLB and NAV and AP1

- Sometimes, the A310 continues accelerating past the calculated speed (250 IAS for example) and speeds of the 390 (!) knots

- It doesn't seem to stick to the calculated or manually set speed at all

- Workaround: I have to switch AP off and on again, turn off the the desired modes and turn them back on again

So I'm asking myself, what is going wrong here?

Thx

Malte

Hello,

Could you post a screenshot of your MIP when this happens next?

Cheers.

[Cammac]

Hi,

Thanks for the post. 

I think your issue may be coupled to an auto flight protection system in the A300/A310. If you ever see THR L shown this means the aircraft went over a set AOA and will try and protect itself by applying full power and the only way to reset this mode is toggle the A/THR on and off. 

In reference to this thread: 

 

 

The behaviour you are seeing is indeed correct. When you are in PROFILE the target is to stay at idle as long as possible the only way this is possible is to increase or decrease the target speed while staying at idle. If the target speed drops below the target speed -25kts ( I believe ) it will trigger to P.SPD again and come back on target speed. You see the same thing with the 320 family but it draws the speed window. This is not the case on the A310 /  A300. 

If you are using very high CI then the speed target will be very much right on VMO / MMO which I can see in the one screenshot but the A310/A300 will reduce thrust when reaching MMO and VMO but often you will end up high as the aircraft has no way to get back on profile as it can't speed up. This can also be seen on the 32 family.

Cheers.