Thomson B738 at Lanzarote and Fuerteventura on Aug 22nd 2013, fuel emergency

Last Update: May 18, 2016 / 15:59:58 GMT/Zulu time

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Photo of Thomson Airways G-FDZG, Boeing 737-800 — Thomson Airways G-FDZG, Boeing 737-800 (Photo credit: Deanster1983 on and off for now / Flickr / License: CC by-nd)

Incident Facts

Date of incident
Aug 22, 2013

Classification
Incident

Airline
Thomson Airways

Flight number
BY-4460

Departure
London Gatwick, United Kingdom

Destination
Lanzarote, Spain

Aircraft Registration
G-FDZG

Aircraft Type
Boeing 737-800

ICAO Type Designator
B738

A Thomson Airways Boeing 737-800, registration G-FDZG performing flight BY-4460 from London Gatwick,EN (UK) to Lanzarote,CI (Spain) with 169 passengers and 7 crew, was on a VOR approach to Lanzarote's runway 03 circling runway 21 when after turning final to runway 21 a sudden wind change destabilized the aircraft and prompted the crew to go around. The crew subsequently decided to divert to Fuerteventura and declared emergency due to landing with final fuel reserve intact was no longer ensured. The aircraft climbed to 5000 feet enroute to Fuerteventura, the crew performed a visual approach to Fuerteventura and landed safely about 25 minutes after going around at Lanzarote.

Spain's CIAIAC put up notice on Nov 4th 2013, that an investigation into the occurrence has been opened (editorial note: suggesting that landing may have been below final fuel reserve).

On Sep 11th 2014 Spain's CIAIAC released an interim statement detailing the progress of the investigation. In this statement the CIAIAC reported that the crew prepared for a VOR approach to runway 03 at Lanzarote. While on the downwind the crew received instruction to fly over the LTE VOR and perform a VOR approach to runway 21 as dictated by wind changes. After the aircraft had been established on final to runway 21 a sudden change in wind destabilized the approach prompting the crew to initiate a go around. Runway 03 became active again causing problems in Lanzarote's approach sector due to proximity of Lanzarote and Fuerteventura Airport and certain runway configurations affecting maneouvering. ATC sent the arriving aircraft into different holding patterns to route the traffic.

Due to the problem with the approach to Lanzarote the crew decided to divert to Fuerteventura and was cleared for a visual approach to Fuerteventura. As the fuel remaining was approaching reserve fuel the crew declared Mayday and continued for a safe landing, the passengers disembarked normally.

The investigation so far focussed on analysis of the go around maneouver and coordination between crew members as well as analysis of aircraft and crew performance using quick access recorder data, radar data, company documentation and instructions received. In addition the investigation analysed the actions of the air traffic controllers at Lanzarote and Fuertaventura, weather data and the problems specific to the approach sector.

The investigation is currently waiting for Enaire (former AENA Air Navigation) to approve mitigating measures intended to resolve the problems identified in the Canaries Approach Sector.

The final report draft is in an advanced phase.

On May 18th 2016 Spain's CIAIAC released their final report concluding the probable causes of the incident were:

The incident was caused by the execution of a non-precision approach at a high rate of descent with a tailwind. This resulted in a go-around maneuver and a subsequent diversion to the alternate airport, which forced the crew to declare a fuel emergency (Mayday).

Contributing to the incident was:

- The limiting characteristics of the Canaries AAC sector, which hampered traffic management.

The CIAIAC reported in their factual presentation:

After planning an approach to runway 03 and while on the downwind leg, they were instructed to proceed to the LTE VOR and make a VOR approach to runway 21, since changing wind conditions required a change in runway. Once on the final approach, a sudden change in the wind destabilized their approach, as a result of which the crew executed a go-around.

The change in the active runway in Lanzarote, which reverted to its original configuration with runway 03 in use half an hour later, caused congestion problems in the ACC Canaries Approach sector. This is a highly complex sector due to the proximity of the Lanzarote and Fuerteventura (GCFV) airports, and due to how their operations affect one another when in certain runway configurations. In an effort to manage the flow of arriving traffic, aircraft were directed to enter various holding patterns.

In light of the problems encountered by approaching traffic, the crew decided to proceed to its alternate airport on the island of Fuerteventura, where they were cleared to make a visual approach. Since the fuel remaining was approaching final reserve fuel, the crew declared an emergency (Mayday).

The landing was normal and the passengers left the aircraft in an orderly fashion. There was no need to do an emergency evacuation.

The incident was reported via the Event Notification System, meaning the investigation was started two months late, on 24 October 2013.

The CIAIAC reported the captain (60, ATPL, 12,060 hours total, 780 hours on type) was pilot flying, the first officer (42, ATPL, 5,300 hours total, 1,150 hours on type) was pilot monitoring.

During the first pass over Lanzarote airport at 5000 feet there were 2400kg of fuel remaining on board. The aircraft subsequently flew downwind and joined final approach to runway 21. About 3.5nm before the runway threshold the aircraft descended through 1170 feet MSL at 1100 fpm, slightly below the glidepath, wind there was from 040 degrees at 18 knots. While descending through 370 feet MSL the rate of descent increased to 1470fpm prompting an EGPWS sink rate alert, winds were from 005 degrees at 15 knots. Descending through 50 feet AGL at 156 KIAS (12 knots above Vapp) at 1150fpm rate of descent, winds from 350 degrees at 15 knots amounting to 11 knots tail wind component, the crew attempted to continue the landing, at 10 feet AGL the thrust levers were at idle and winds were from 350 degrees at 2 knots, the crew now initiated a go-around applying TOGA, the aircraft did not make contact with the runway. The aircraft settled in the climb, flaps were reduced to 15 degrees and the landing gear was retracted, at 1170 feet MSL autothrust was engaged, fuel remaining at that point was 1900kg.

The aircraft continued to clean up and climb to 5000 feet at 250 KIAS, after levelling at 5000 feet and engaging the autopilot fuel remaining was 1530kg prompting the crew to make their decision to divert to Fuerteventura.

While on a 3nm final to Fuerteventura's runway 01 the crew declared emergency estimating they would touchdown with 1000kg of fuel remaining before required final fuel reserve (1090kg of fuel). The crew reported in post flight interviews with the CIAIAC that they landed without further problem at 1000kg of fuel remaining.

The CIAIAC analysed: "Thomson’s fuel policy calls for its crews to adhere to the fuel requirements shown on the Operational Flight Plan (OFP). The captain must provide a reason for taking on additional (EXTRA) fuel. In fact, the policy states the company’s preference to have a crew divert to the alternate airport than to carry extra fuel as a matter of course. This measure is clearly economic in nature, as it aims to control overall fuel consumption at the company. It also conditions the crew’s decision-making ability, though the final decision is the captain’s, as the person ultimately responsible for the operation."

The CIAIAC analysed the approach and go around:

As they were making the approach, the crew configured the aircraft to make a stable approach, which was made using the automatic lateral and vertical navigation modes.

This takes some of the workload off the crew and provides greater accuracy in following a stable descent angle. These modes were used until they reached 2350 feet, close to the published MDA of 2000 ft, where the autopilot and autothrust were disengaged.

From then on, the recorded sink rates reached values in excess of the 1000 feet per minute required for a stabilized approach, as per Thomson’s criteria. Below 500 ft AAL, values of up to 1470 fpm were reached. This triggered the “sink rate” alert from the EGPWS at an altitude of 370 ft. At that point the crew should have started the goaround maneuver.

By increasing the ground speed, the presence of a tailwind component on final approach requires increasing the sink rate to stay on the desired glide slope.

When the flare maneuver was initiated at 50 ft, the IAS was 156 knots. This was 12 knots over the approach speed (144 knots). The sink rate was 1150 fpm, which exceeds the limits established by Thomson.

During the flare, at a radioaltitude of 10 ft, the IAS was 163 knots, 19 knots above the approach speed.

Finally, when they detected that the aircraft was floating, the crew decided to execute the standard go-around maneuver. This decision was made too late, in light of the problems encountered during the approach maneuver to remain within the stabilized approach parameters. At 1070 ft, the crew engaged the autopilot, which adjusted the pitch angle to maintain an initial climb speed of 174 knots (flaps 40º approach speed + 20). The lateral HDG SEL and vertical LVL CHG modes were engaged. Shortly afterwards they also engaged the autothrottle. At 1200 ft they reduced thrust and selected the LNAV lateral tracking mode.

This is when they reported the go-around to the tower. The fuel onboard was 1900 kg, very close to the amount required by the OFP to proceed to the alternate airport in Fuerteventura plus the final reserve fuel.

With respect to cleaning up and the diversion to Fuerteventura the CIAIAC analysed:

The frequency change and the instruction to turn to heading 090º coincided with the flap retraction sequence. The current vertical navigation mode maintains the initial MAP speed, which is the speed needed to fly safely in a 15º-flap configuration, but it does not increase the speed unless commanded by the crew. In the automatic VNAV vertical navigation mode, this process happens automatically and the crew only has to retract the flaps at the indicated speeds.

With the lateral navigation mode selected, the crew began the flap retraction sequence, but they forgot to increase the airplane’s speed. As a result, the aircraft began turning at a 30º bank angle in LNAV in a clean configuration at 175 knots. The minimum speed for selecting flaps up is estimated to have been 201 knots, meaning the aircraft was 26 knots below this speed.

Upon reaching 4500 ft, CWS P was displayed on the PFD. The autopilot was then disengaged. This implies that the pilot realized his mistake and made an input to the control column to lower the pitch angle that overrode the autopilot, which was subsequently disengaged. Following this indication, the crew accelerated to 250 knots and climbed to 5000 ft before once more engaging the autopilot.

The flight parameters were just above the minimum maneuvering values (shown on the PFD as a yellow strip shown on the wind gauge). This means that the aircraft was able to maneuver at 1.3 g’s. For the maneuver performed, this means that if the bank angle had been 10º steeper, the stick shaker would have activated, warning of an imminent stall. It should be noted, however, that the LNAV lateral navigation mode, which was engaged, does not allow a bank angle in excess of 30º.

After this occurrence, which should have peaked the crew’s alert level, they assessed the amount of fuel remaining and the possibility of not being able to land in Lanzarote due to the wind conditions, since other aircraft were also going around.

When the fuel amount fell to 1530 kg, they decided to proceed to the alternate. This decision is deemed to have been correct, since the amount of fuel needed to fly to Fuerteventura, shown on the OFP, was calculated to be 760 kg, assuming FL090.

Upon contacting Fuerteventura and being cleared to make a visual approach, the crew rigorously adhered to the requirements of its Operations Manual Part A, declaring a fuel emergency (MAYDAY) when they realized that the fuel available to land (1000 kg) was below the final reserve fuel (1090 kg). This policy is in keeping with the European regulation that governs air operations (EU OPS CAT.OP.MPA.150 Fuel policy).

With respect to ATC the CIAIAC analysed:

Due to the wind conditions at the Lanzarote Airport, the controller on duty at the tower, run by the air navigation services provider SAERCO, changed the runway in use twice in a span of under 30 minutes. The high traffic flow in the Canaries AAC sector leads controllers to rely on the published holding patterns due to the limitations present in this sector.

The controller in the Lanzarote tower fulfilled his responsibility to change the runway when the readings in the tower suggested such a change. Despite complying with the terms of the letter of agreement regarding notifying his colleague in the ACC, this notification was not provided sufficiently in advance for the ACC controller to be able to route arriving traffic to the new runway, while at the same time handling departing traffic.

His task was complicated by the missed approach maneuvers of traffic attempting to land on runway 21 at Lanzarote.

Though the controller in the Lanzarote tower had prior experience as a military controller, the air navigation services provider SAERCO had only been in charge of the facility for 40 days, meaning the controller probably lacked experience in assessing the operational environment specific to this airport.