Created Thursday, Jan 20th 2022 18:34Z, last updated Wednesday, Jul 12th 2023 07:06Z
A Hop! Embraer ERJ-170 on behalf of Air France, registration F-HBXG performing flight
AF-1671 from Lyon to Caen (France), was enroute at FL280 about 70nm southeast of Paris when the aircraft was overflown by a Cessna 550 business jet, that had been cleared to climb to FL270. Both aircraft were able to continue to their destinations without further incidents.
The BEA reported the Cessna 550, performing a flight from Paris Le Bourget (France) to Geneva (Switzerland) encountered problems with their autopilot while climbing through FL230, the pitch angle increased and the aircraft suffered a load factor. The aircraft had been cleared to climb to FL270, but overflew the Embraer ERJ170 that was enroute at FL280. The Cessna crew reported they had a malfunction of the #1 altitude and speed indication system, the transponder therefore reported erroneously they were on FL270. This created a loss of separation with the potential of a collision without triggering TCAS. The BEA rated the occurrence an incident (?) only and opened an investigation.
On Jul 12th 2023 the BEA released their final report concluding the probable causes of the serious incident were (referring to the Citation only, naming the E170 the "other" aircraft):
The following factors may have contributed to the loss of separation with another aeroplane:
- the crew not giving immediate and explicit information to the controller concerning the differences in altitude indications observed between systems 1 and 2;
- the controller not giving clear information to the crew, concerning the nature and origin of the altitude information available to him on his screen, in response to the question from the crew who had not formalised their doubt;
- the captain's confirmation bias generated by the controller's response to the crew's question (similarity of indications in near-stabilised flight);
- the crew of F-HGPG giving late information to the controller concerning the altitude differences between the system 1 and 2 altimeters, limiting the options available to the controller to manage the conflict;
- the absence of a (manufacturer and/or operator) crew procedure to deal with cases of faults or uncertainties with respect to the air data system indications.
The following factors may have contributed to an air data system being kept in an unsafe technical condition:
- inappropriate practices with respect to the reporting and technical processing of occurrences in the Valljet Citation sector which have been shown to be ineffective and may reflect a deficient safety culture;
- shortcomings in the Textron Aviation maintenance manual, in particular the absence of a suitable troubleshooting procedure for this type of situation.
The absence of operational procedures for the crew may have contributed to inadequate operational management of an in-flight fault on an air data system because of:
- the limited scope of the actions taken by EASA after the serious incident of 2010, in particular with respect to the observed shortcomings of the flight manuals drawn up by the manufacturers and in relation to situations of doubtful or erroneous air data information;
- inadequate practices with respect to the reporting and operational processing of occurrences at Valljet which meant that it did not identify the need to produce this type of procedure.
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