An A319 Captain reported that he missed an assigned descent crossing restriction after slowing his airspeed for turbulence. Descent path deviation detection was difficult because of fatigue; the PFD Level Off point is updated slowly and its symbology different from his previous aircraft.

Narrative

We were on a direct routing. We were told to cross our next fix at FL240. I started the descent in 'managed descent' and the FMS showed that we were right on the path to make the restriction. As we descended through about FL280 we entered a cloud layer and started to get light and then moderated turbulence. I immediately slowed the aircraft to turbulent penetration airspeed (275 KIAS) while continuing the descent. I then realized; too late; that we were not going to make the restriction. We crossed at about FL250 (1;000 FT high) and were handed off to the next controller. There was no mention of our being too high or of a conflict of any kind. As far as CRM goes the First Officer and I had flown together before and work well together. We were at the end of a 13 hour duty day. We are both fairly new on the aircraft. He went through training in March 2010 and I went through in May 2010. Speaking for myself; I have 20 years on Boeing/McDonnell Douglas aircraft; and those FMS displays have a continuously updated 'green arc' that shows exactly where your aircraft will level at the selected altitude. The Airbus display is different. It has a small blue arrow that shows the level off point; but is not updated as quickly. I think that was a contributing factor in my delay in realizing that I was too high; after having slowed down for the turbulence.