Description

On 25 December 2013, an Airbus A330-300 (G-VNYC) being operated by Virgin Atlantic Airways on a scheduled international passenger flight from Tobago to St . Lucia as VS98 completed a stable approach in night IMC but the crew found that the initial landing roll needed atypical intervention to ensure direction along the runway was maintained and detected both ‘juddering’ and a more significant rate of deceleration than usual. Considerable impact damage to the lower fuselage and below-floor systems was subsequently discovered.

Investigation

An Investigation was carried out by the Eastern Caribbean CAA under the provision of the St Lucia CARs 2007. Relevant recorded flight data was obtained from Airbus. A Preliminary Report detailing initial progress with the Investigation was published on 23 August 2018.

It was noted that the 50 year-old Captain had a total of 13,000 hours flying experience of which 9,800 hours were on the A330/340. The 30 year-old First Officer had a total of 4,783 hours flying experience of which 807 hours were on the A330.

It was established that the crew were on the second flight of their duty which had consisted of a return trip to Tobago and that on arrival back in St. Lucia, the aircraft was scheduled to continue to London Gatwick. After a delayed departure due to reports of thunderstorm activity, heavy rainfall and strong and gusting winds at St Lucia which had resulted in intermittent closure of the airport, the flight departed Tobago with the First Officer as PF. On checking the St Lucia weather en route whilst still 128 nm southwest of destination, the crew were advised of “thunderstorm activity at the field...thunderstorms in all quadrants”. Fifteen minutes later, when 18 nm southwest of the airport, the crew asked if the airport was still open and were told it was currently closed. They opted to take up the hold and await an improvement.

Half an hour later, ATC advised the flight that visibility at the airport had improved and, after asking the crew to standby for an imminent METAR, the controller then gave it as including present weather “thundershowers (with) CBs in all quadrants”, adding that the airport was now open. The aircraft, with the Captain now having taken over as PF, was cleared to commence an RNAV approach to runway 10.

A stable approach was flown and the 2744 metre-long runway was in sight shortly after descent through 1000 feet agl with the AP disengaged at 600 feet agl. However, on main gear touchdown 700 metres past the threshold and 6/7 metres right of the centreline at 135 KCAS with the auto brakes set to MED, a significant ‘juddering’ was immediately obvious. The crew also reported that, for no obvious reason, the aircraft had veered to the left - although this was easily brought under control. The nose landing gear touched down at approximately 120 KCAS and the FDR recorded an immediate 3° left turn and then an 8° right turn onto 107° at a speed of 75 knots followed at 40 knots by a further 6° to the right which resulted in the centreline being regained. As the landing roll continued, a series of ECAM cautions were displayed, including a left wing air leak.

The aircraft taxied to its parking gate and was shut down. The attending ground engineer then summoned the Captain to come outside and look at the aircraft where there was extensive damage to the underside of the aircraft in the vicinity of the pack bay where the fuselage structure had been pushed upwards. System damage was found to the ducting of the cross bleed system, to pack ducting and possibly to the packs themselves and also to several brake units. The Captain initially concluded that “the aircraft may have struck a solid object on the runway”. However, the Investigation concluded that “the nature of the damage to the belly panels in the vicinity of the pack bay area indicates that the aircraft had come into contact with a significant amount of water at high speed”. The depth of this water was estimated from the evidence available as having been at least 30 cm deep and possible as much as 60 cm.

The source of this water was the “Petite Riviere du Vieux Fort” (see the illustration below) which had, unknown to ATC, burst its banks where its natural channel turns from south to west and begins to parallel the runway, a change made to facilitate runway extension. It was considered that the un-commanded change in aircraft direction after touchdown “may have been the result of aquaplaning”.

It was noted that after the aircraft had parked but prior to passenger disembarkation, water from the river “began flooding the airport terminal, the ramp and runway area” with this second deluge believed to have deposited debris such as logs / branches, ULDs and other baggage handling equipment subsequently seen on the runway and surrounding areas later in the night.

The Conclusions of the Investigation included the following:

• the nature of the damage sustained by the aircraft points to the aircraft coming into contact with a significant amount of water at high speed. There is no evidence to indicate that the aircraft struck anything else.
• the original course of the river to the north of the runway had been diverted to facilitate a past runway extension and as a result of the heavy rain that prevailed in the hours prior to the investigated landing, the river had burst its banks at the point where the original course of the river had been diverted 90 degrees to the west which had led directly to the touchdown area of the runway in use being flooded at the time of the landing.
• the evidence indicates that at the time of the investigated landing, the depth of water where touchdown occurred was between 30 cm and 60 cm in depth.

Seven Safety Recommendations were made as a result of the Investigation as follows:

1. that the St Lucia Authorities should implement more frequent runway inspections during periods of severe weather conditions in order to check for flooding.
2. that the St Lucia Authorities should install physical ‘high level’ indicators to warn of rising water levels in the adjacent river to the north of the Airport.
3. that the St Lucia Authorities should install flood defences in order to prevent future runway contamination at the Airport should the river burst its banks.
4. that the St Lucia Authorities should install Unit Load Device (ULD) and ground equipment storage areas at the Airport that would avoid these items being carried by flood waters or high winds onto the runway in adverse weather conditions.
5. that the St Lucia Authorities should ensure that clearance to land is not given unless the controller can be reasonably assured that the runway is free from significant standing water during periods of heavy rain.
6. that the Eastern Caribbean Civil Aviation Authority (ECCAA) should, given the potentially serious outcome of this occurrence, share the investigation results and recommendations with industry safety forums and other Caribbean operators.
7. That Virgin Atlantic Airways should issue a summary of this report to all its flight crew and should advise them that during periods of bad weather, a runway inspection can be requested prior to landing.

The Final Report was completed on 2 September 2015 and subsequently published.

Related Articles

• Rain
• Cumulonimbus (Cb)
• Runway Surface Friction
• Aquaplaning
• Runway Availability