Help with Airbus 320-200

[EHM-2198 Didimo]

A couple of days ago I flew the  the main fleet's A320 for about an hour. I just took off from MPTO on the active runway (offline flight) with default fuel (full I think) and default cargo.

It flew beautifully, I took it up to 25000 en route to Limon, Costa Rica and did various maneuvers. I was able to step wise push the speed to nearly 320 knots IAS and perhaps a little bit more, anyway M0.80 I remember.

Being satisfied with it I decided to take the bird on an official flight from KATL to MPTO thinking that at that speed (M0.80) I could arrive in 3:30-4:00 hours (as in real life).

I started with 27000 pounds of cargo after lowering it down. In any case the default config was a bit off balance (COG forward). I loaded some 30000 pounds of fuel.

Well, to my surprise now I am right now at 33000' and in the past 2 hours I have not been able to push it past 220 KIAS without overspeeding

At this moment it is flying on this configuration:
 - Airspeed 218 KIAS 9on the PFD vertical strip)
 - Winds 093 degrees /09 knots
 - Heading 182
 - Ground speed 331 Knots
 - Autopilot ENABLED
 - Autothrottle ENABLED
 - AP Speed: 218 ENABLED
 - Altitude 33000'
 - Pitch trim 2.8-3.0 (controlled by autopilot)
 - Fuel On Board (now) 17940 pounds

In other words it should be the most fuel efficient mode, auto and at high altitude.

I don't know whether starting to dump fuel or what, at this speed the sun will rise and I will have to go to work.

Any ideas what I am doing wrong?

[EHM-2155 Mariano]

Mate as you climb higher, the mach numbers are easier to "achieve" so, at 270 and 320 kts being m0.8, and 330 at 220 being 0.8,  sounds about right... Check your ground speed it should be around 400 kts.

[EHM-2198 Didimo]

Well I am at FL330 with the speed indicator at 218 which is what I set as target speed on the autopilot. The tape shows M0.57 as the speed and not M0.8

[EHM-2155 Mariano]

That is definetly weird, what happens if you set your AP to mach mode and push it to 0.78?

[EHM-1749 Hector]

Strange indeed. At FL330 and 218 KIAS, provided standard temperature rates, M should be 0.63 and the KTAS 364.
This link can help to understand how M varies with altitude:
http://www.hochwarth.com/misc/AviationCalculator.html

[EHM-2097 Andrei]

I can think of one explanation...

BEFORE ever stating it, note that I DO NOT imply pilot error, it may still be a technical problem. I think this exact  behaviour will happen when the aircraft reaches cruise level with one notch of flaps out. I am thinking especially at the pitch angle, which seems quite low for a "clean" Airbus at low speed, but could be consistent with some flaps out.

I noted that on some aircraft, when the model and the panel do not match very well, it is possible to see no flaps or full flaps on the gauges while the reality is "slightly" different (one or several notches may not be apparent on the panel).

Andrei

[EHM-2198 Didimo]

Interesting note Andrei, I spent the whole flight trying to figure out what I could do to fly with a lower pitch. Normally one pitches up a little bit to slow down the a/c at that crucial speed where a pitch up will not cause the plane to gain altitude.

However, I am 100% sure my flaps were up because it was in my after takeoff schedule and my lever was 100% up. Also the indicator on the panel as far as I remember was back at 0 degrees.

During my first test of the A3xx in combination with the MCP Pro (new toy) it stalled, crashed and burned some minutes after takeoff. The air crash investigator (myself :-) noticed that the flaps had not been fully retracted. That was also a very good note for me to learn about this bird's characteristics before commiting it to my first PP flight on it.

It must have been something, what I do not know but I found it strange that some days before I could push it at 300+ at FL250. That was the only reason why I used it.

I guess I might take it for another (much shorter) ride and see if it exhibits the same behaviour.

[EHM-2089 Vincent]

I have been using the A320-200 for my Mediterranean Tour and did not notice any of those problems. I usually leave my pitot and de-icing on for a while when flying on higher altitudes. The usage of autopilot should not affect anything. However I had seen my IAS drop to around 250 odd, but my GS was sitting at more than 400 at that time. Try an empty cargo and passengers scenario and see if it repeats. Dis-engage autopilot and push those throttles to full and see if it makes any difference too.
On the tour, I flew most of the short ones below FL250 while I had a couple that had been flown on cruise alt.