On 7 February 2010, a Boeing 737-300 being operated by Jet2 on a scheduled passenger flight from Leeds/Bradford UK to Chambery France was making an Instrument Landing System (ILS) approach to runway 18 at destination in day Instrument Meteorological Conditions (IMC) when a Mode 2 Terrain Avoidance and Warning System (TAWS) ‘Terrain, Pull Up’ Warning occurred. A climb was immediately initiated to Visual Meteorological Conditions (VMC) on top and a second ILS approach was then made uneventfully. Despite extreme pitch during the early stages of the pull up climb, none if the 109 occupants, all secured for landing, were injured.
An Investigation was carried out by the UK AAIB. The Cockpit Voice Recorder (CVR) had been overwritten but useful Flight Data Recorder (FDR) data was recovered except for the recorded position which was derived from the FMS and therefore “susceptible to errors”. Download of the EGPWS computer provided useful information and the ATC radar recording allowed aircraft position to be determined accurately.
It was noted that in the light of a State Requirement for commanders of all commercial flights to receive special training from their company before they are allowed to fly to Chambery, Jet2 had designated the destination as a Category ‘C’ airfield and provided its crews with a special brief. The aircraft commander was found to have received this training four years earlier as a First Officer and although he had since complied with the annual recency requirements, had not received any further training when he was promoted to Captain.
It was established that the First Officer had been designated as PF because had the light northerly wind increased as forecast, it might have meant that a circling approach to Runway 36 would be required “for which the right hand seat pilot would have been better placed to maintain a clear view of the runway”. In fact, the wind remained light and the aircraft was cleared for a straight in ILS to Runway 18.
FDR data showed that the ILS LLZ had been captured normally with the AP engaged and that descent on the ILS had been commenced at a range of 11 nm but with VS (Vertical Speed) selected rather than the ILS GS. This would have complied with Company SOPs had a circling approach followed the ILS but was contrary to SOP for a normal auto ILS approach, even at the steeper than normal GS angle at Chambery of 4.46° as this should be done with APP mode engaged. As VS mode was engaged, the aircraft was already about 850 ft below the ILS GS and began to descend at about 2200 fpm with the speed increasing slowly from 160 knots to 175 knots. At a range of 8.6 nm from the runway, where the ILS track passes over a ridge of high ground, the terrain closure rate suddenly increased to over 6,000 fpm and when the terrain clearance reduced to 1125 feet, an EGPWS Mode 2 Hard ‘Pull Up’ Warning was activated. Almost simultaneously, the AP was disconnected and a climb commenced from a minimum recorded terrain clearance of 1,112 ft. It was noted that the limitations attributable to FDR data recording rates meant that it was not possible to determine if the climb had been initiated just before the EGPWS warning as reported by the crew.
During the subsequent climb, airspeed reduced from 175 knots to 110 knots during the approximately 40 seconds it took to climb from an altitude of 3500 feet to VMC at 6000 feet where the aircraft was levelled. The rate of climb averaged about 3,800 fpm and the recorded pitch attitude reached a maximum of +37° within 15 seconds of the climb commencing before then reducing to around 25° until approaching 6000 feet. No reference is made by the investigation to the weight of the aircraft during the climb and the corresponding stalling speeds.
The Final Report: AAIB Bulletin: 12/2010 EW/C2010/02/03 of the Investigation was published on 9 December 2010.