Airbus A320 200 I BIKE 06 06 Essay

Submitted By 景皓-张
Words: 4973
Pages: 20

AAIB Bulletin: 6/2006



Aircraft Type and Registration:

Airbus A320-200, I-BIKE

No & Type of Engines:

2 CFM-56 turbofan engines

Year of Manufacture:


Date & Time (UTC):

25 June 2005 at 0740 hrs


On approach to Runway 09L at London Heathrow

Type of Flight:

Public Transport (Passenger)

Persons on Board:

Crew - 6

Passengers - 98


Crew - None

Passengers - None

Nature of Damage:

Failure of No 1 and 3 ADIRUs

Commander’s Licence:

Airline Transport Pilot’s Licence

Commander’s Age:

41 years

Commander’s Flying Experience:

8,300 hours (of which 1,300 were on type)
Last 90 days - 130 hours
Last 28 days - 50 hours

Information Source:

AAIB Field Investigation

The aircraft had departed on a scheduled passenger

whilst attempting to diagnose the problem, contrary

flight from Milan to London Heathrow Airport, with

to prescribed procedures. As a result, additional data

an unserviceable No 3 Air Data Inertial Reference Unit

was lost from the commander’s electronic instrument

(ADIRU). On final approach to Runway 09L at London

displays, the nosewheel steering became inoperative and

Heathrow, in Instrument Meteorological Conditions

it became necessary to lower the landing gear by gravity

(IMC), the Inertial Reference (IR) part of the No 1

extension. The aircraft landed safely.

ADIRU failed, depriving the commander (the pilot

History of the flight

flying) of much of the information on his Primary Flight and Navigation Displays. ATC required the aircraft to

The history of the flight is derived from multiple sources,

go-around from a height of 200 ft on short final approach

including data from both the Flight Data Recorder

due to another aircraft still occupying the runway. The

(FDR) and Cockpit Voice Data Recorder (CVR).

co-pilot, who had been handed control, performed the go‑around and the aircraft was radar vectored for a second

The flight departed from Milan Airport at 0547 hrs on a

approach. The crew then turned off the No 1 ADIRU

scheduled flight to London Heathrow Airport (LHR) with

© Crown copyright 2006

AAIB Bulletin: 6/2006



the commander as the Pilot Flying (PF). The previous

co‑pilot, whose PFD and ND were functioning normally,

day, the No 3 ADIRU was found to be unserviceable

and the ILS approach was continued.

and had been turned off; the Minimum Equipment List
(MEL) allowed the aircraft to depart in this condition, as

At about 0724 hrs, the flap lever was set to position

both the Nos 1 and 2 ADIRUs were serviceable. During

three. Shortly after this time the aircraft started to

the flight, as a precautionary measure, the commander

deviate from the glideslope and localiser. The aircraft

and co-pilot reviewed the Flight Manual Abnormal

altitude continued decreasing and, by about 300 ft radio

Procedures for the actions to be taken in the event of a

altitude and when at an airspeed of 130 kt, the aircraft

second ADIRU becoming unserviceable.

had deviated some 1.3 ‘dots’ below the glideslope.
Almost coincident with this, the CVR recorded an

Following an uneventful transit, the aircraft was given

EGPWS “glideslope” warning (see Figure 1 Point B).

radar vectors and became fully established on the ILS

The deviation below the glideslope continued to

approach to Runway 09L at LHR. Two stages of flap

increase and a second EGPWS “glideslope” warning

were selected and, at 1,820 ft (QNH), the landing gear

was recorded by the time the aircraft was at some

was lowered. Some 16 seconds later, just as the landing

1.84 ‘dots’ below the glideslope.

gear locked down, the Inertial Reference (IR) part of the
No 1 ADIRU failed and a ‘NAV IR 1 FAULT’ message

As the crew continued their approach, ATC advised that

appeared on the aircraft’s Electronic Centralised Aircraft

they would receive a late clearance to land. When the

Monitor (ECAM).

The autopilot and