Singapore B773 at Munich on Nov 3rd 2011, runway excursion
Last Update: December 17, 2018 / 16:15:06 GMT/Zulu time
- The crew decided to conduct an automatic landing even though the conditions on the ground for a safe conduct were not given.
- Shortly before touch-down the airplane was deviated to the left of its flight direction by the disturbed LOC signal. A BAE 146-RJ85 taking off a short distance ahead of the B 777 caused the interference.
- The two pilots could not keep the airplane on the runway after touch-down because the autopilot was still engaged.
- The crew was confused by the behaviour of the airplane. They had not noticed that the go-around mode had already been deactivated by the initial touchdown of the left main landing gear.
- The recommendation concerning the conduct of autoland landings under CAT I conditions published in the FCOM of the operator allowed the decision for an autoland landing without having to consider the required conditions on the ground.
The BFU analysed:
After analysing and assessing the facts, the BFU came to the conclusion that the airplane veered off the runway because the localizer signals had been distorted by a departing aircraft. All three receiver antennas of the airplane received identical signals from the localizer on the ground so that on board no malfunction was indicated. Because there was only a short interference of the localizer signal neither the near field nor the far field monitor - which monitor the proper function of the ILS - registered a malfunction of the ILS. This means, the airplane followed the localizer signal.
The crew only realised about 30 ft above the runway that something was not correct as the airplane slightly banked to the left and then drifted left. The left main landing gear touched down directly afterwards which resulted in the disengagement of the go-around mode. This prevented the crew from being able to initiate an automatic goaround.
The preparation and conduct of the approach and the intended automatic landing were in accordance with the valid flight operations procedures of the operator. The fact that both pilots had arrived from Singapore two days prior to this flight suggests that, at the time of the occurrence, they did not experience an increase in psychological stress due to jet lag. The flight occurred at a favourable time for the crew - in Singapore it would have been afternoon - and therefore fatigue is not really feasible.
The crew did not inform the approach controller of their intention to conduct an automatic landing.
The crew knew that under the prevailing CAT I flight operations the safety measures of all-weather operations CAT II/III were not present.
Therefore, the crew had to take into consideration that ILS interferences due to other airplanes on the ground or in the air were possible.
Based on the crew statements the BFU is of the opinion that the crew was prepared to initiate a go-around procedure in case of an incident. The PIC stated that as the airplane dipped the left wing shortly before touch-down he wanted to initiate a goaround and pushed the TO/GA button. Even though the PIC’s command “Okay, flaps twenty.” did not completely meet the requirements of the standard phraseology for a go-around “Go-Around Flaps 20” it was his command to go-around. The analysis of the FDR showed that the co-pilot did not set the flaps to 20°. The crew stated that in their estimate a go-around procedure initiated manually with an airplane already on the ground would have been much more dangerous than remaining on the ground.
The FDR analysis in combination with the sonogram indicates that the TO/GA button was pushed simultaneously with the initial ground contact of the left main landing gear. The crew anticipated that the Go-Around Mode would initiate a go-around, but nothing happened. The Go-Around Mode had deactivated as designed by Boeing (system logic) by the initial ground contact of the main landing gear.
The PIC realised that the ground spoilers had already been deployed automatically and retracted them manually. This would not have been necessary. Had he pushed the thrust levers forward the ground spoilers would have been retracted automatically and the autobrake function deactivated.
The BFU is of the opinion that both pilots, the PIC due to him being an instructor pilot and the co-pilot having enough flying experience on type, were sufficiently familiar with the go-around procedure. These procedures were sufficiently described in the FCTM and had been trained sufficiently in the simulator in accordance with effective regulations.
Relocation of the Instrument Landing System
At Munich Airport the localizer antennas were moved from 350 m to 1,000 m beyond the runway threshold. The air traffic service provider stated that it had become necessary because of the Airbus A380 operation to prevent localizer interferences through reflections off airplanes.
The BFU is of the opinion that the position change of the LOC antenna effected the separation of approaching and departing aircraft. In order to prevent interferences with the LOC antenna separation inevitably would have to be increased. Furthermore, the broadcast antenna diagram has to be pooled better by about 3.6° to ensure the required accuracy for CAT II and CAT III approaches which results in an increase in energy supply by approximately 0.1 W.
Behaviour of the Air Traffic Controllers
The controller stated that he had been under a high workload, because of all-weather operations in the morning (CAT II/III), delays had occurred which, at the time of the occurrence, resulted in an increased departure rate in combination with approaches on runway 08R. This forced the controller to work on the edge of the separation minimum so that aircraft waiting to depart could do so quickly and traffic situation would become normal. Since the controller did not have any information that the crew intended to conduct an automatic landing he did not separate the aircraft in accordance with the required separation minima for CAT II/III but for CAT I conditions; i.e. separation between departing and approaching aircraft was one runway length. The air navigation service provider stated that if the controller had been informed he would not have allowed the BAE 146-RJ85, waiting on taxiway B4, to take off ahead of the B 777.
At the time of the occurrence the provision phase for CAT II/III was still active even though the weather situation would have allowed for the cancellation of all-weather operations CAT II/III in accordance with the Manual of Operations Air Traffic Services (MO-ATS). Air traffic had already begun to separate the aircraft in accordance with CAT I. Provided the crew had informed the controller about the planned autoland the option would have existed to return to CAT III operations. This would have been possible with relatively little effort because the protection zones were still free since the change from CAT II/III to CAT I conditions and the waiting departing aircraft still stopped at the CAT II/III holding point.
The investigation determined that autoland landings under CAT I conditions are conducted without informing air traffic control. If an international regulation for such cases existed that air traffic control had to be informed about an intended autoland the controllers would have been better prepared and might have made appropriate preparations.
If the airport does not operate on LVP, it should become global standard to inform air traffic control on time about an intended autoland landing.
This article is published under license from Avherald.com. © of text by Avherald.com.
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