Serious incident to the Cessna 525 registered F-HGPG operated by Valljet and to the Embraer ERJ170 reistered F-HBXG operated by HOP on 12/01/2022 en route
Fault on an air data system en route, proximity with an aeroplane without activation of anti-collision systems
The crew of the Cessna 525 CJ registered F-HGPG were carrying out a flight between Paris-Le Bourget airport (Seine-Saint-Denis) and Geneva airport (Switzerland).
During the climb, following a sudden variation in the nose-up attitude with the autopilot engaged in IAS mode, the crew observed erratic speeds on the system 1 airspeed indicator. After a short manual flight phase, the climb was continued with the autopilot in VS mode. Later, when approaching the en-route level, the crew realised that there was a difference in altitude between the two altimeters (system 1 and system 2). The cross-check with the help of the controller who had the flight level transmitted by the aeroplane’s transponder displayed on his radar screen did not enable the crew to identify that the system 1 altimeter indications were erroneous. The climb was continued to the en-route level based on an erroneous altitude.
En route, after having observed that the left and right altimeters were giving different indications, the crew informed the controller of the onboard altimeter fault. The latter then informed the crew of converging traffic (the Embraer 170 registered F- HBXG) at a distance of 2 NM, in theory 1,000 ft higher than them. In reality, the traffic was lower than them (the minimum separation was estimated at 665 ft and 1.5 NM). No collision avoidance system warning, whether it be on the ground or onboard the Embraer 170 was emitted, as the systems had analysed erroneous data from the Cessna 525. Subsequently, the controller asked the crew to deactivate the transponder Mode C, he coordinated with the Swiss control services and the flight continued to Geneva, its destination.
The head of the control centre room attempted to determine the actual altitude of the aeroplane with the help of the National air operations centre (CNOA), however, the latter did not have additional altitude information. However, another parameter, the aeroplane’s altimeter setting, which the CNOA shared with the controller proved to be erroneous. The investigation was not able to determine the cause of this difference.
The investigation showed that the fault on air data system 1 (altimeter and airspeed indicator on captain’s side) had already occurred three times on this aeroplane in 2017, 2019 and 2021.
The BEA has issued six safety recommendations concerning five topics:
- maintenance documentation published by Textron Aviation;
- notification of technical faults at the operator, Valljet;
- DSNA quick reference card when a pilot has a doubt about the altitude of his flight;
- information transmitted by CNOA;
- EASA’s analysis of the risk posed by an air data system fault.
Maintenance documentation published by Textron Aviation
The BEA recommends that:
- whereas a TSM for the Cessna 525 does not exist;
- whereas the tasks in the maintenance manual relating to the air data system exclude aeroplanes modified by Service Bulletin SB525-34-41, although some of the actions set out in this task may be relevant to these modified aeroplanes;
Textron Aviation supplement the maintenance documentation to specify the actions to be taken in the event of an air data system anomaly for all versions of the Cessna 525, including those modified by SB525-34-41.
[Recommendation FRAN-2023-016].
The follow-up of this recommendation has been completed. Please consult SRIS2 for information about the adequate response to this recommendation.
Notification of technical faults at the operator, Valljet
The BEA recommends that:
- whereas the inappropriate practices observed during the investigation with regard to the reporting of technical incidents, in particular the failure to report faults in the TLB;
- whereas some of these practices continued after the serious incident of 12 January 2022, in particular the failure to report faults in the TLB;
- whereas the operator seems to persist in requesting that the detection of a technical fault in flight be subject to validation by the managers directly linked to flight operations;
whereas paragraph CAT.GEN.MPA.105 is one of the requirements applicable to the crews of commercial air transport operators;
Valljet review its organisation, procedures and practices so that captains are encouraged, in accordance with requirement CAT.GEN.MPA.105 of the consolidated European regulation No 965/2012 known as "Air Ops", to immediately record themselves in the TLB, at the end of each flight, the faults observed, without having to obtain prior validation by an operations manager or by an expert pilot, and without being concerned that restrictive measures will be taken against them.
[Recommendation FRAN-2023-017].
The follow-up of this recommendation has been completed. Please consult SRIS2 for information about the adequate response to this recommendation.
- whereas the inappropriate practices observed during the investigation with regard to the reporting of technical incidents, in particular the failure to report faults in the TLB;
- whereas some of these practices continued after the serious incident of 12 January 2022, in particular the failure to report faults in the TLB;
- whereas the operator seems to persist in requesting that the detection of a technical fault in flight be subject to validation by the managers directly linked to flight operations;
- whereas requirement ARO.GEN.300 requires the oversight authority to verify the "continued compliance with the applicable requirements of organisations it has certified”;
- whereas paragraph CAT.GEN.MPA.105 is one of the requirements applicable to the crews of commercial air transport operators;
the DSAC ensure that the Valljet operator remains in full compliance with paragraph CAT.GEN.MPA.105 of the consolidated European regulation (EU) No 965/2012 known as "Air Ops", under requirement ARO.GEN.300 of the same regulation, by actively seeking all useful information, such as crew reports, data collected by OSAC as part of the oversight of the operator's CAMO and Part 145 maintenance workshop, and exchanges and correspondences between flight operations, the CAMO, as well as the Part 145 maintenance workshop(s) used by the operator.
[Recommendation FRAN-2023-018].
The follow-up of this recommendation has been completed. Please consult SRIS2 for information about the adequate response to this recommendation.
Quick reference card for controller
The BEA recommends that:
- whereas the emergency procedure for when a pilot announces that he has a doubt about the altitude of his flight is not directly accessible in the control position;
- whereas a pilot contacting a controller about an altimeter issue should alert the controller;
the DSNA ensure that the emergency procedure relating to a pilot's doubt about the altitude of his flight is the subject of an quick reference card, made available to controllers at their control position and is accompanied by recurrent training on a simulator.
[Recommendation FRAN-2023-019].
The follow-up of this recommendation has been completed. Please consult SRIS2 for information about the adequate response to this recommendation.
Information transmitted by CNOA
The BEA recommends that:
- whereas unreliable information may be transmitted by the CNOA to air navigation service providers in the course of a cross-check;
the CNOA determine the limitations of its systems and the data at its disposal in order to provide relevant information to air navigation partners.
[Recommendation FRAN-2023-020].
This recommendation is being processed. Its status can be consulted on SRIS2.
Analysis of risk posed by an air data system fault
The BEA recommends that:
- whereas the failure of an air data system can simultaneously:
- lead directly to a deviation in altitude conducive to a loss of separation with other aircraft or to the ground in controlled flight,
- compromise the situational awareness of pilots and controllers due to the possibly erroneous information available to them,
- compromise the operation of protection systems against the risk of collision in flight or the risk of collision with the ground in controlled flight;
- whereas aircraft with different certification criteria operate in the same airspaces, thus reducing the effectiveness of the most demanding requirements with respect to this risk;
whereas the analysis of the risk posed by a fault on the air data system is not carried out in a global manner;
EASA continue and complete the analysis of the risk posed by a fault on the air data system, taking into account the system as a whole, and draw, as applicable, any conclusions regarding safety actions.
[Recommendation FRAN-2023-021].
This recommendation is being processed. Its status can be consulted on SRIS2.
[1] Continuing Airworthiness Management Organisation.
[2]Serious incident to the Cessna 525A registered N222NF on 4 August 2020 close to Bourget (Seine-Saint-Denis).
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Note: in accordance with the provisions of Article 17.3 of Regulation No 996/2010 of the European Parliament and of the Council of 20 October 2010 on the investigation and prevention of accidents and incidents in civil aviation, a safety recommendation in no case creates a presumption of fault or liability in an accident, serious incident or incident. The recipients of safety recommendations report to the issuing authority in charge of safety investigations, on the measures taken or being studied for their implementation, as provided for in Article 18 of the aforementioned regulation.