The Aviation Safety Network have a record for the accident. It seems like the aircraft was fitted with the wrong Fuel Quantity Indicator which was reading fuel quantities about 2000 Kg higher than the actual levels. The Fuel Quantity Indicators for both the ATR-42 and the ATR-72 looked the same and were fitted the same way, but used different algorithm to calculate the fuel level.
I know very little about the airline industry, but my basic engineer's guess tells me that such a critical subsystem should not leave room for confusion. Design common sense would suggest using as many common parts as possible across models to reduce manufacturing costs, but not when people's lives depend on them.
I recently found the 5-minute recording from the blackbox:
The conversation was a mix of Arabic, French, English and Italian. A blogger has published a transcript of the conversation. The mechanical engineer Chokri didn't make it, but the pilot survived although he was badly hit. A survivor said: "I saw the pilot on the wing. He was in a terrible state and blood covered his face."
Here is the same transcript with little corrections I made. The commander is Chafik Al Gharbi (شفيق الغربي), the second pilot it Ali Kebaier Lassoued (علي كبيّر الأسود).
Hours 15,34' 33"
- commander: check whether it started. Leave it, leave it.. in the name of God, most compassionate, most merciful. What's the ditching procedure?
- second pilot:
- commander: confirm the distance, please.
- Palermo control: [incomprehensible]
- commander: confirm the distance, please.
- Palermo: the distance is now 20 miles.
- commander: I think… we are not able, we are not able to reach the terrain. We are at four thousand feet and we are not able, we loose both engines. Can you send for us helicopters or something like that?
- second pilot: ditching.. ditching (talking to self while going through the procedures manual)
- commander: fast, fast.
- Palermo: I can advise.
- second pilot: preparation.
3'33" to the splash down
- commander: it's better we turn towards that ship, it's better if we turn towards that ship.
- second pilot: should I put [incomprehensible]
- commander: no, no, the wind is strong, the wind is strong. Oh! God be clement. In name of God the merciful one, the clement one, in name of God, the merciful one, the clement one...
- second pilot: cabin and cockpit: prepare.
- commander: so this one still doesn't start?
- second pilot: no, it refuses to start.
- Palermo: 1153, Palermo, be informed that we informed ... the ships... Your position is about 22 miles now radial 20… 036,… radial 036, 22 miles.
- commander: uhhh, the battery! Unable, unable to reach, 2200 feet. There are two boats, we are going to join them, left side, heading 180, can you call them please?
- commander: try again, try again (trying to restart the engines)
- Palermo: heading 180, confirmed?
- commander: which one have you ignited, which you have ignited? (stressed tone)
- second pilot: the right one.
- commander: go, go. The other one, the other one!
- second pilot: already did, it refuses to start!
- Palermo: Tuninter 1153, Palermo, say again!
- commander: there is a boat, there is a boat… left side… I'm going to put there. 1100 feet. In the name of God the merciful one, the clement one.
- second pilot: auto, press, dump.
- commander: prepare for emergency ditching.
Less than 1' 55" to the ditching
- Palermo: you are at about… now the position is approximately… 20 miles to east of the field
- commander: Unable to reach, unable to reach
- second pilot: not in a position to reach land. Tuninter 1153 unable to reach the field, we see two ships on the left side, big boats. We try to land… to ditch near of them. If you can call them, please…
- second pilot: before ditching. Optimal ditch altitude. Minimise impact slope. Brace for impact (reads out the ditching procedure)
- commander: good
- second pilot: [incomprehensible] (reads on, seems nervous)
- commander: did it start? try the other one
Less than 27" to the ditching
- commander: is that the sound of the engine?
- second pilot: the same, the same, it does not want to make anything
- commander: God be clement, God be clement
- second pilot: gear level… up… ditch push button before.
- commander: go, it's over now, help me Ali. Be alert Ali. Chokri, get ready, Chokri get ready.
- Chokri: I am ready
- commander: we're touching the sea.
- commander: in the name of God the merciful one, the clement one, in the name of God the merciful one, the clement one
Splash-down hours 15,38' 53"