A350 autothrottle

As I was cruising in the A350, I noticed that even though I set the speed to Mach 0.85, the speed on the PFD (Primary Flight Display) was indicating 0.84. So in order to cruise at 0.85, I had to set the speed to 0.86, and sure enough, the speed was now 0.85. Same thing as when I was climbing (still in the A350), the autothrottle never reaches the selected speed, it would always fall a few knots short. Anyone else experiencing this issue?

1 Like

Crosswind and Headwind, and/or the Weight of you aircraft may make the plane fly slower than the assigned Speed you’ve given it through the AP. There are plenty of factors that play in to what speed your aircraft will fly.

I has some strong crosswind yesterday on heavy loaded A359, and found myself flying 0.84 when I set the AP 0.85, but today, right now, with minimal wind, nothing that will effect the speed much, I’m cruising comfortably at 0.85 when the AP is set 0.85.

3 Likes

Yeah you’re right, however with previous aircraft, they always maintain the target speed.

1 Like

The speed discrepancy is a known issue.
It will probably and hopefully be looked at soon.

5 Likes

The A350 very so, like previous planes, do keep the speed, and much like the previous planes also loose or gain speed depending on wind speed and direction. I’m not sure, or I don’t believe Temperature matters in IF, but as for Wind and how Heavy you are in relation to what altitude you’re flying, that will impact on how much thrust your engines need to put out, and what your actual true speed will be, not the estimated/indicated one :)

So I’d say, try taking the A350, light weight, with minimal to no winds on Solo Mode, set AP to Mach 0.85 and cruise at desired altitude of your choice and see for yourself if the plane does reach 0.85 or not when winds are calm and the weight is low.

2 Likes