Easyjet A320 at Paphos on Jan 7th 2015, Alpha Floor Activation on approach

Last Update: August 11, 2016 / 16:21:39 GMT/Zulu time

Bookmark this article

Photo of Easyjet G-EZTE, Airbus A320 — Easyjet G-EZTE, Airbus A320 (Photo credit: RHL Images / Flickr / License: CC by-sa)

Incident Facts

Date of incident
Jan 7, 2015

Classification
Incident

Airline
Easyjet

Flight number
U2-2133

Departure
London Luton, United Kingdom

Destination
Paphos, Cyprus

Aircraft Registration
G-EZTE

Aircraft Type
Airbus A320

ICAO Type Designator
A320

An Easyjet Airbus A320-200, registration G-EZTE performing flight U2-2133 from London Luton,EN (UK) to Paphos (Cyprus) with 157 passengers and 6 crew, was on approach to Paphos' runway 29 turning base and descending through 3000 feet when the aircraft climbed to 3800 feet, its speed dropped from 197 to 161 knots over ground, the aircraft descended again to 3400 feet, the speed stabilized at 190 knots over ground and the aircraft performed a go-around climbing to 4000 feet. The aircraft subsequently positioned for another approach to Paphos' runway 29 and landed safely.

On Mar 18th 2015 the French BEA reported in their weekly bulletin under the category "Loss of Control inflight", that the Alpha Floor protection activated on approach to Paphos. The occurrence was rated a serious incident and is being investigation by Britain's AAIB.

On Aug 11th 2016 the AAIB released their bulletin reporting the first officer (2800 hours on type) was pilot flying, the captain (39, ATPL, 4,500 hours total, 4,200 hours on type) was pilot monitoring. The crew had briefed both an instrument and a visual approach to Paphos' runway 29, a number of potential threats were discussed in the briefing including the effects wind would have on timing of the downwind leg and crosswind on final approach.

Upon contacting Paphos the crew made visual contact with the aerodrome and requested a visual approach, which was approved. The crew had selected the track/flight path vector push button to get the flight path vector indication instead of the flgiht directors. After receiving clearance for a further descent to circuit altitude of 1500 feet MSL the first officer selected open descent and brought the engines to idle. On the left downwind for runway 29 the aircraft passed abeam the threshold runway 29 at 3500 feet MSL, about 42 seconds later the first officer disconnected autopilot and started the base turn, the aircraft descending through 3100 feet at 165 KIAS, the standard operating procedure calls "autopilot off" and "flight directors off" were omitted however, the flight path director remained active. At the same time tower instructed revised go-around instructions, the aircraft should maintain runway heading and climb to 2000 feet, which were read back by the captain.

The first officer noticed the speed was decaying while in the base turn, the captain assumed, looking outside to assess the base turn, that the speed decay was intention and queried whether the first officer wanted flaps 3, which the first officer confirmed. Flaps 3 were selected. The aircraft descended through 2860 feet MSL, 5 knots above minimum selectable airspeed (Vls) and a pitch of +12 degrees nose up. The speed continued to decay, at Vls-2 the first officer became focussed with the decaying airspeed, but provided a further nose up input which reduced the rate of descent and increased the speed reduction. ALPHA FLOOR activated and the autothrust system automatically applied TOGA thrust. The first officer called "ALPHA FLOOR" and a few seconds later, realising he had lost situational awareness, handed control to the captain.

At that point the aircraft was climbing through 2900 feet MSL at a pitch of +10.5 degrees nose up. The commander, whose attention had been outside of the aircraft, was startled by the first officer's announcement, turned the aircraft away from the coast line and terrain and instructed "Go Around, Flaps". TOGA thrust was selected to match the thrust levers with the actual engine thrust, the flaps were reduced to position 2. As the aircraft continued to accelerate and climb, the speed reference system engaged again and the Vapp speed as well as the flight director bars re-appeared. The flaps were selected to 1, Autothrust was selected off and the thrust levers reduced to regain control of thrust. The landing gear remained down.

When the aircraft climbed through 3900 feet a TCAS Resolution Advisory "Level Off! Level Off!" sounded, the pitch was reduced and the aircraft began to descend, after descending through 3860 feet the TCAS announced "Clear of Conflict". The aircraft continued to descend to 3380 feet when ATC instructed the flight to climb to 4000 feet. The aircraft climbed to 4000 feet, after being level at 4000 feet autothrust and autopilot were re-engaged. The aircraft subsequently performed an uneventful ILS approach to runway 29.

The AAIB annotated the minimum speed during the occurrence was Vls-7 knots. As result of the TCAS RA activation a minimum vertical separation of 1000 feet had been maintained to an aircraft above the A320.

The AAIB discussed:

On the A320 series, when the autopilot is disconnected in OP DES mode, the FD remains engaged in thrust mode, commanding IDLE thrust, and provides pitch commands for the PF to maintain the target speed. Thrust will not increase when the pitch commands are not followed and there is a decay in speed, until the low speed protections activate. To revert to SPEED mode and resume variable thrust, the flight director must be switched off.

Flight crew are accustomed to the speed protections afforded by the A/THR system and the two events reported on by the BEA demonstrate that, if misunderstood, there can be an expectation that the A/THR will vary the thrust to maintain the target speed.