TAM A319 near Rio de Janeiro on Jun 17th 2011, airborne contact with hot air balloon causes unreliable speeds

Last Update: October 1, 2013 / 20:22:01 GMT/Zulu time

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Incident Facts

Date of incident
Jun 17, 2011

Classification
Report

Flight number
JJ-3756

Aircraft Registration
PT-MZC

Aircraft Type
Airbus A319

ICAO Type Designator
A319

A TAM Linhas Aereas Airbus A319-100, registration PT-MZC performing flight JJ-3756 from Rio de Janeiro Santos Dumont,RJ to Belo Horizonte,MG (Brazil) with 95 passengers and 6 crew, was climbing out of Santos Dumont Airport when air traffic control advised of presence of (unmanned) hot air balloons in the area. When the aircraft climbed through about FL120 at 275 KIAS the crew noticed a hot air balloon dragging a plastic banner which contacted the aircraft. Immediately afterwards all airspeed indications disagreed and autopilot and autothrust disconnected, messages "MAINTENANCE STATUS F/CTL", "NAV ADR DISAGREE", "F/CTL ALTN LAW", "AUTO FLT AP OFF", "AUTO FLT A/THR OFF" and "NAV ALTI DISCREPANCY" were shown on ECAM. The captain instructed the first officer to disregard the "NAV ADR DISAGREE" message and did not inform Air Traffic Control. The crew attempted to reconnect the flight directors and autopilot however without success. The crew partially executed the unreliable speed checklists - while the first officer read the checklist the commander switched the ADR data sources and identified ADR3 as not working, the crew however did not rearrange the systems to use ADR1 and ADR2 instead. Subsequently the crew referred to the pitch/power tables using an aircraft weight of 66 tons although the actual aircraft weight was 54 tons and the table for 56 and less tons should have been used. Although the aircraft was no longer compliant with requirements for RVSM airspace, the crew did not notify ATC and continued the climb manually into RVSM airspace levelling off at FL310. Throughout the flight a multitude of alerts regarding deviations from altitude and heading occurred. During the descent air traffic control complained the aircraft was 1nm off track and queried whether they would be able to conduct an ILS approach to Belo Horizonte. The crew configured the aircraft for flaps on the ILS approach to Belo Horizonte's runway 13, the captain identified the speed indications of left and right PFD disagreed by more than 10 knots with the first officer's instrument showing the higher value, the captain decided to use the first officer's indications without checking whether his or the first officer's indications were more reliable. When the crew lowered the landing gear the message "F/CTL DIRECT LAW" was shown on the ECAM. The crew continued for a safe landing.

Brazil's CENtro de Investigacao e Prevencao de Acidentes aeronauticos (CENIPA) released their final report in Portugese reporting, that as result of impact with the banner all three dynamic ports of the pitot system as well as a TAT probe were obstructed. CENIPA concluded the probable causes of the serious incident were:

The collision of the balloon with the aircraft was the main factor to the occurrence of the serious incident, which resulted in the discrepancy and inaccuracy of basic flight parameters and in the degradation of the automatic systems.

Contributing factors were:

There was inadequate management of duties of each crew member to the extent that actions were not requested, performed or completed although required by standard operating procedures like defined by task sharing by the manufacturer, the ECAM actions and checklist items.

Both pilots triggered their sidesticks simultaneously creating a dual input, when the crew spotted the balloon so close that insufficient time remained to avoid the balloon. It was not possible to determine whether the pilot actions contributed to the collision.

The investigation could not decide whether the crew continued the flight into RVSM airspace, onto a RNAV approach and onto an ILS approach without required systems being available because of forgetfulness or ignorance.

The training programme of the operator had not completed training of unreliable airspeed and ADR check procedures in all phases of flight and did not cover all items recommended by the aircraft manufacturer, with respect to frequency of simulator training it is possible that there was lack of familiarity with the tables used in emergencies.

CENIPA reported that the captain (9,163 hours total, 3,074 hours on type) was pilot flying, the first officer (5,951 hours total, 2,651 hours on type) was pilot monitoring. During departure from Santos Dumont the captain demonstrated the "update function" of the inertial system on the progress page of the FMGS, while following the departure route PORTO-6. Suddenly both crew spotted the balloon and both reacted triggering their sidesticks in order to avoid a frontal collision with the balloon, the banner however hit the aircraft and obstructed all three dynamic ports of the pitot system as well as a TAT probe. CENIPA analysed that due to the demonstration of the FMGS the attention of both crew member was diverted inside the aircraft causing reduced monitoring of the exterior. Hence the crew detected a balloon on their trajectory late prompting both crew members to move their sidesticks, causing a "dual input" message, in order to take an evasive maneouver, which however could no longer prevent contact with the balloon.

CENIPA continued analysis stating that as result of the banner having obstructed all dynamic ports and a TAT probe all automatic systems were degradated causing the autopilot and autothrust to disconnect, the flight controls change to alternate mode, the standby speed indicator becoming inoperative. All these messages and events would have required to run the relevant checklists, however, the captain did not assign task sharing and did not request the first officer to perform the related ECAM actions. Instead the crew attempted to reset the flight director and autopilot to no avail.

The analysis continued saying that the captain instructed the first officer to disregard the "NAV ADR DISAGREE" message, which however would be the most important tool to detect discrepancies in indicated air speed and suspect unreliable airspeed. The captain finally instructed the checklist unreliable airspeed but interrupted the execution of the checklist when he identified ADR3 as inoperative and changed some switches to select another source. In doing so the commander executed a task that he as pilot flying and monitoring the first officer running the checklist should not have executed. After executing memory items several items of the checklists were omitted including to inform air traffic control and check the accuracy of airspeed and altitude as well as other indications off the air data reference units. The crew thus still could not determine whether ADR1 or ADR2 were providing reliable data. The unreliable air data reference units should have been shut down.

Although the aircraft had lost systems mandatory for operating in RVSM airspace as well as mandatory to perform the arrival route and ILS approach the crew did not report the occurrence to air traffic control or advise of the inability to perform the procedures. As result numerous alarms like altitude and heading deviations occurred in cruise flight, the aircraft went more than a nautical mile off the approach track.

CENIPA continued analysis stating that the weather was extremely favourable to deal with the emergency by providing visual meteorologic conditions throughout the flight, which also helped to compensate for the unfamiliarity of the first officer with the pitch/power tables.

The lack of familiarity with the scenario, the lack of familiarity with the pitch/power tables, the lack of task sharing and monitoring, the lack of coordination with air traffic control, the lack of compliance with checklists as well as low situational awareness have all aggravated the situation. An annual simulator training in compliance with the aircraft manufacturer's recommendations could have resulted in a different performance by the crew.

The release of balloons create a risk of collision with aircraft as the trajectory of unmanned balloons can not be controlled and may enter areas of intense air traffic. Although balloons are generally objects of low intensity, the high speed and energy of aircraft pose the danger of a catastrophic outcome. Even though the collision with a balloon has been (partly) considered in aircraft design, the impact of the fire source or accessories of the balloon with the aircraft's engines or gear may create a fire hazard, cause engine failures and take out air data reference systems. In this case a balloon of 10kg caused an impact force of 2.26 tons, a balloon of 50kg an impact force of 100 tons due to the aircraft moving at more than 250 KIAS. The balloon caused all air data references to be obstructed and could have caused a catastrophic outcome to 101 occupants of the aircraft.

In general there have been 143 sightings of balloons by aircrews in 2012, several of which required partly extreme evasive maneouvers to prevent a collision. The balloons such pose a significant danger to Brazilian Aviation.
Incident Facts

Date of incident
Jun 17, 2011

Classification
Report

Flight number
JJ-3756

Aircraft Registration
PT-MZC

Aircraft Type
Airbus A319

ICAO Type Designator
A319

This article is published under license from Avherald.com. © of text by Avherald.com.
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