Tuninter Flight 1153

The report has a long 366 pages. So I can only extract some of the info from it to discuss.

If you intended to read the full report. https://bit.ly/Report_1153 同上次一樣~黑色係summary; 藍色係我小小諗法~

Final Report Accident Tunisian flight 1153 ATR72-212 Summary The accident occurred on August 6th, 2005, at 13.39 UTC (15.39 local time) and involved an ATR 72-202 aircraft, registration marks TS-LBB, operating the flight TUI 1153 from Bari to Djerba (Tunisia). The aircraft had ditched into the sea off the coast of Capo Gallo (Palermo) following the failure of both engines. The aircraft had taken off from Bari at 12.32 UTC with 39 people on board (4 crew members and 35 passengers, among which 1 airline engineer). While cruising, approximately 50 minutes after takeoff, at flight level 230 (FL 230, 23.000 feet), the right engine shut down (no. 2) and after approximately 100 seconds also the left engine shut down (no. 1). The flight crew decided to divert to the airport at Palermo, Punta Raisi, to make a precautionary landing. The crew referred to having tried to restart both engines, but without success. After gliding for approximately 16 minutes, the aircraft ditched approximately 23 nautical miles northeast from Pale

rmo's airport, Punta Raisi, within Italian territorial waters. On impact with the surface of the sea, the aircraft broke into three pieces; 14 passengers, the airline engineer and a member of the crew (senior flight attendant) reported fatal injuries. The other occupants suffered serious to minor injuries. Summary 無咩好講~

Fuel quantity indicator

The day before the accident, inefficiency of the right wing fuel tank fuel indicator recorded faults on the aircraft’s log book, as required by the airline’s procedure.

Pilots are required to record any fault or abnormal observation on the aircraft logbook; so the maintenance will either input the item to MEL or have it~

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The FQI is an instrument processing the signal from the capacitive sensors installed in the wing

fuel tanks, based on an algorithm, which is specific to each type of aircraft, depending on the shape of the tanks, their sizes and the number of probes. The wing fuel tanks of ATR 42 and ATR 72 aircraft are different in terms of maximum capacity, shape, number and positioning of the capacitive probes. Therefore, ATR 42 and ATR 72 type FQIs use different algorithms and cannot be interchanged. As we will ascertain later on, the fuel quantity indications provided by an ATR 42 type FQI, mounted on an ATR 72 aircraft, are higher than the actual quantity of fuel contained in the wing fuel tanks.

Normally, the mechanics will follow the procedure stated on the AMM Aircraft Maintenance Manual, and research on the IPC Illustrated Parts Catalog to look for Parts. Some aircrafts have common parts, which is interchangeable. However, in this case, the FQI is not interchangeable. Although they look almost the same, but that’s not interchangeable.

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In this particular case, refuelling did not take place because the Block Fuel request (1400 kg) was lower than what was actually indicated by the flight instruments (by the FQI and by the repeater placed on the refuelling panel). In fact, the quantity indicated was approximately 3100 kg. A refuelling slip was therefore filled out, stating that the refuelling operation had not been completed because the quantity of fuel present in the aircraft was higher than required. (The fuel remaining from flight before was 770 kg, half of the required.)

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Neither the refuelling operator, nor the engineer realised that instead of the 700 kg (approximately 900 litres) that should have been pumped into the aircraft (from 3100 to 3800 kg), only 465 kg (600 litres) were in fact pumped. Once refuelling was complete, the co-pilot completed the pre-flight operations and the flight captain checked the aircraft flight documentation assisted by the FD. In checking the previous refuelling operations carried out on the aircraft, the flight captain realised that the fuel slip for the refuelling of the aircraft from the quantity of 790 kg (the total fuel remaining after the last flight of the aircraft and recorded by himself the previous day in the Performance Record) to 3100 kg, the value indicated by the FQI before refuelling up to 3800 kg, was missing. The FD asked his colleague in the office if he had a copy of this slip. The answer was negative. The supervisor of the ramp engineering services was also contacted by phone by the FD, and he indicated that he was not aware of such an operation.

The FD therefore informed the flight captain that at the moment he was not certain where the fuel slip (from 790 kg to 3100 kg) was, but that it was highly likely that one of the crews planning to complete the previous routes, subsequently cancelled, might have mistakenly kept the copy of this refuelling slip. The FD therefore reported to the flight captain that he would take charge of obtaining the missing fuel slip, which he would have handed to him upon return from the flight. The flight captain decided to complete the flight with the documentation for the refuelling he had requested, but without the one confirming the previous refuelling operation from 790 kg to 3100 kg, on the basis of the information received by the FD. In situations of unclear or missing documentation occur, the flight captain should inform the Flight Operations Director. In this case it was not done. The co-pilot stated that the flight captain had not involved him in this problem. The ferry flight to Bari (TUI 152F), with two pilots, the two flight attendants and the maintenance engineer, was completed uneventfully. The aircraft took-off at 12.05 local time (10.05 (UTC) and landed at Bari at approximately 13.46 local time (11.46 UTC). The duration of the flight was therefore 101 minutes, in agreement with the distance flown.

Due to the wrong FQI installed, the indication was wrong. The refueller and the engineer didn’t pick on the mistake, also the pilots. Normally, the refueller will provide pilots the fuel receipt. We need that piece of information to compute the refueling amount and error. But sometimes, ground staff are being pressured to maintain OTP on time performance. They tend to rush the pilot to minimize the delay. Therefore, there is a norm. The more you rush; the slower I get. As they are rushing, there is more chances to commit errors; pilot needs to make sure and safeguard that error won’t affect safety. Airline are concerned with their reputation of OTP, but when safety gets into a concern; OTP is not as important.

Cruise phase TUI 1153 requested FL 230, the final cruise flight level. This was also granted. At 13.21.36 (approximately four minutes since the previous radio communication), TUI 1153 requested permission to descend to FL 170 due to technical problem (the PNF did not specify to air traffic control the type of problem occurring). From the analysis of the data recorded by the FDR, it appears that in fact the right engine had shut down by itself (uncommanded shut down). Due to other traffic presence, Rome ACC did not authorise the aircraft to descend directly to the requested flight level (FL 170), but gave initial authorization to descend to FL 190. At 13.23.00, after approximately two minutes, TUI 1153 communicated that they wanted to land at Palermo. By now also the left engine had shut down, approximately 100 seconds after the first one (data taken from FDR). In giving authorization to descend to FL 170, Rome ACC asked if special assistance was needed. This communication overlapped with the previous one of TUI 1153 and was not understood by the crew. TUI 1153 transmitted the MAYDAY declaration (emergency condition declaration), confirming the need to proceed for Palermo. The controller in contact repeated the authorization to descend to FL 170, confirming receipt of the emergency message, and at the same time coordinating the management of other traffic, to enable the TUI 1153 to proceed directly for Palermo. At 13.24.19, TUI 1153 transmitted once more the MAYDAY declaration, asking to be vectored (to receive radar guidance) for Palermo and confirming they had lost both engines (“We lose both engines”).

我連埋下面先一次過comment~

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1.1.9. Operations inside the cockpit

This paragraph describes the operations carried out inside the cockpit from the moment the first failured occurred until ditching, on the basis of the information gathered from the aircraft recorders FDR/CVR and from the declarations of the pilots. From taking-off from Bari until the shut down of the first engine (right-hand engine) approximately 49,50 minutes passed, and both the operations inside the cockpit and the communications with the involved air traffic control units (Bari TWR, Brindisi ACC and Rome 15 ACC) were carried out normally, without any communications of faults. After the right-hand engine shut down, while at flight level FL 230 (23.000 ft), TUI 1153 requested to descend to FL 170. In the meantime the crew was trying to understand, based on the visual and acoustic warnings inside the cockpit, why the right-hand engine had suddenly shut down. In fact, the “FEED LO PR” light had come on (fuel feed low pressure), together with a decrease of the engine torque, the flowmeter and the “ITT” temperature, all indicating an uncontrolled shut down of the right-hand engine. After coordinating the descent to FL 170 with Rome ACC, the co-pilot started reading out loud the check list (Procedures following failures – page 2.13 of the QRH) for the procedure to follow for the type of failure detected (FEED LO PR).

Feed LO PR即係無fuel pressure, 無油到engine. (但係FQI 仲indicate 有油)

During the reading of the relevant check list, approximately 100 seconds after the righthand engine shut down, the flight captain requested that the co-pilot stop reading, because also the other engine (left) had shut down. He then ordered the co-pilot to inform air traffic control of the decision to divert the aircraft to Palermo, Punta Raisi, and declare the emergency (MAYDAY). For about a minute the pilots tried to interpret the indications of the cockpit instruments warnings and identify the reasons for the failure of both engines, but unsuccessfully. The flight captain communicated again the MAYDAY to Rome ACC, informing them at the same time that both engines had failed (“[omissis], we lose both engines”).

The aircraft was at an altitude of approximately 17.000 ft. The flight captain asked the senior flight attendant to call the airline engineer to the cockpit. A minute later the engineer, who had been sitting in the rearmost passenger row, entered the cockpit and took up position between the two pilots, attempting to assist in restarting the two engines. Some attempts to restart the engines were made, but unsuccessfully.

因為佢地覺得仲有油,所以attempt to restart engine! 當single engine, 正常pilot 會maintain 一個safe speed (180kt) to ensure handling quality 同windmilling effect to assist restart. 唔會太care 個glide. 因為只要restart 到其中一個engine 都recover 到. 所以relighting the engine is the first priority.

In consideration of the distance from Palermo airport, given several times via radio by Palermo APP, the flight captain, upon comparing this distance with the altitude, called the senior flight attendant and asked him to prepare the passengers for a possible ditching. Five minutes and thirty seconds had passed from the moment the second engine had shut down, and the aircraft was now at an altitude of 12.000 ft and at a distance slightly less than 40 NM from Palermo airport. Both the flight crew and the engineer were unable to understand what type of fault had occurred to the two engines.

The distance from Palermo was repeatedly requested and after a last attempt, unsuccessful, to restart the right-hand engine, with the aircraft at an altitude of 4000 ft and at a distance of 20 NM from Palermo airport, the flight captain informed the ATC controller that they were unable to reach the runway and requested that the emergency services be dispatched. Twelve minutes had passed from the time both engines had shut down.

During the restart, Captain has already made the decision of diverting, regardless if the engine will relight or not. Only question is if they will make it to the airport or not.

A few seconds after informing Palermo APP that the aircraft was unable to reach the runway, the flight captain asked the co-pilot to read the ditching procedure check list. The flight captain continued to carry out his role of PF, while the co-pilot read the ditching check list. In the meantime, the flight captain informed ATC that he was unable to reach the airport and wanted to go left onto heading 180°, as he could see two boats (“there are two boats, I am going to join them left side, heading 180”), and asked if it would be possible to inform the boats of the situation. The co-pilot continued to complete the checks listed in the ditching check list, including those for the landing gear and confirming its retracted position (“Landing Gear: UP”).

The flight captain, in view of the imminence of the ditching, asked the co-pilot to assist him in the steering of the aircraft and to get ready for the impact. The ditching check list was not completed. A little before the impact, the captain also recommended the engineer, who had remained in the cockpit, to also get ready. After 22 seconds the aircraft impacted on the sea surface. Nearly 17 minutes had passed from the moment the first engine had shut down, to the ditching. The last valid data recorded by the flight data recorder (FDR) was at 13.37.089. The last recordings of the noises and sounds inside the cockpit (CVR) were at 13.38.05, approximately one minute after, and coinciding with the effective time of ditching.

When both engines quit, the aircraft can only descent and glide; consider ATR is a very streamline-designed aircraft, it doesn’t have a long gliding time or distance. Consider the length of the checklist and the limited time under massive pressure, the ditching checklist might not able to be finished.

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An examination of the RH engine propeller revolutions (NP) reveals that they remained high and constant, as the CL’s were not retracted into the feather (FTR) position, and the propeller kept up the same number of revolutions as it did with the engine running as a result of windmilling. The engine design, known as free turbine, is characterised by the fact that the propeller rotation speed (measured by the NP parameter) is independent of the gas generator compressor-turbine unit speed (low and high pressure compressor rotation speeds measured by the NL and NH parameters respectively). The CLs were not retracted into the feather (FTR) position as the check list reading was broken off, seeing that the second engine had failed.

Left engine failure

About 100 seconds after the RH engine had shut down, with the aircraft at an altitude of about 21.500 ft, in descent towards 19.000 ft, the LH engine shut down. Flame out occurred while the checks prescribed in the “FEED LO PR” check list (page 2.13 of the QRH) were being carried out 2.13 for the RH engine. The captain thus asked the co-pilot to break off reading the check list and to report the intention of diverting to Palermo Punta Raisi airport. The aircraft, with both engines failed, descended through altitude 20.000 ft after about 42 seconds; during the descent, the crew attempted to find out what the cause of the dual failure might be. The crew did not perform the checks laid down in the check list – emergency section – in the event of dual engine flame out (“BOTH ENGINES FLAME OUT” – page 1.03 of the QRH), but attempted to find out the reasons for the sudden flame-out in both engines from the indications furnished by the other cockpit instruments and reported the emergency situation to the controller in radio contact (MAYDAY declaration). Prior to attempting re-ignition, the aforementioned procedure (“BOTH ENGINES FLAME OUT”) prescribes achieving and maintaining what is known as drift-down speed (VmHB, optimum descent speed). This speed is given in the OPS DATA section in the QRH; with an aircraft mass of 17.000 kg, as in the case in point, said speed is about 129 knots with flaps 0°, and 137 knots for an aircraft mass of 19.000 kg (dotted line in figure 32). At the time of the second failure, the aircraft was flying at a speed of about 180 kts, and the flight crew in any case maintained speeds considerably higher than those prescribed by the procedure down to an altitude of about 6000 ft.

Although the report says the other pilot able to reach to the airport and landed the aircraft, but I personally think it also need to consider human factor( just like Captain Sully’s case)

Of course, the aircraft might able to land safely, with all perfect conditions (all prop feathered, best glide speed) But consider all human factors and thinking process, also the confusions between the FQI and Fuel LO PR indication; I think the pilot tried his best to put the aircraft down and safe some peoples lives. (It might cost more lives if they force landing on land.) (also, some passengers die because they inflated the life vest before escaping the cabin.)

我盡左力簡短地detail! 如果有咩想法, 留言la~