You can refer to the cruise charts in back of the POH for the optimal values.  As Jim said 205 IAS is pretty normal for that altitude.

Try closing the cowl flaps, you will gain some speed knots

14 hours ago, 737_800 said:

Hi,

I am flying with the AFE and am at cruise but the aircraft doesn't speed up, it stuck at 271 kt. GS. I deactivated AFE Cruise Mode and pushed the throttle full forward.

That GS is normal.  

6 hours ago, JaseMelbo said:

That GS is normal.  

No such thing as normal ground speed. That is totally dependant on the winds aloft. 

1 hour ago, Bobsk8 said:

No such thing as normal ground speed. That is totally dependant on the winds aloft. 

Well, but there is such a thing as abnormal ground speed. If the DC-6 were doing 50kts ground speed, or for that matter Mach 2 ground speed, that would be decidedly abnormal. 😉

 

So there is a normal *range* of groundspeed.

 

 

2 minutes ago, eslader said:

Well, but there is such a thing as abnormal ground speed. If the DC-6 were doing 50kts ground speed, or for that matter Mach 2 ground speed, that would be decidedly abnormal. 😉

 

So there is a normal *range* of groundspeed.

 

 

If the DC^ were head into a 100 knot headwind, it's GS would be around 150 knots at cruise. Many who fly sims all the time don't know the difference between indicated airspeed, true airspeed or ground speed. Normal ground speed is a ridiculous statement to make. 

I know the difference. There is still a normal range of groundspeed. In your example, we need around a 200 knot headwind to get 50kts ground speed. That would be abnormal.

In my high-example, we need a supersonic tailwind to get a ~1500mph groundspeed. That, also, would be abnormal, at least on this planet.

Ground speed for a given aircraft does have a normal range. That doesn't mean Xkts is normal and X+1kts is abnormal, but it does mean there is a range of normal ground speed for that plane.

If 271kts ground speed is commonly seen in a given plane, then that can be called a normal groundspeed when someone is concerned that their groundspeed is "low."  It's not low. It's normal, because it falls within the normal range of expected groundspeeds.

 

3 minutes ago, eslader said:

I know the difference. There is still a normal range of groundspeed. In your example, we need around a 200 knot headwind to get 50kts ground speed. That would be abnormal.

In my high-example, we need a supersonic tailwind to get a ~1500mph groundspeed. That, also, would be abnormal, at least on this planet.

Ground speed for a given aircraft does have a normal range. That doesn't mean Xkts is normal and X+1kts is abnormal, but it does mean there is a range of normal ground speed for that plane.

If 271kts ground speed is commonly seen in a given plane, then that can be called a normal groundspeed when someone is concerned that their groundspeed is "low."  It's not low. It's normal, because it falls within the normal range of expected groundspeeds.

 

That is not what I referred to when I posted on "normal ground speed". Someone said that 271 knots ground speed is normal. It is not normal if you have a 80 knot tailwind, or an 80 knot headwind. TAS and IAS are how you judge the speed of an aircraft, not groundspeed. 

2 minutes ago, Bobsk8 said:

TAS and IAS are how you judge the speed of an aircraft, not groundspeed. 

Correct. But when someone comes on and asks questions that indicate they might not fully understand the difference between the 3 speeds, and they're worried that a 271kt ground speed is "slow," the first thing you tell them is that it's normal. *Then* you can get into the differences. You have to get them out of the mindset that 271 is a problem, because it might well not be. 

 

On the other hand, I'm not sure everyone saw it, but OP later came in and clarified that their IAS was 205kt at 18,000 feet, which according to the speed/power table is actually quite fast  as it should be somewhere in the 180's for most weights.