[Peetwo]

The Swiss cheese model & anomalies in AAI -

Good catch CW, although IMO there is still some passing strange anomalies with that AvHerald update that will hopefully get ironed out as the investigation continues.

I also find it passing strange that the UAV industry has taken such a defensive stance, perhaps it was because of the inference to the local mines using drones commercially.

I would suggest to TDC that it is inevitable that there will be a serious collision between a drone and a commercial aircraft.

However it is also highly probable that it won't be a drone that is being operated by a responsible commercial UAV operator but more likely a rogue drone that is being operated through naivety or in direct contravention of State and/or local laws.

Moving on to another international investigation FR, brought to my attention by Baldwin Aviation, into a B737-800 runway overrun in 2013 at Pardubice in the Czech Republic, via SKYbrary:

Description
On 25 August 2013, a Boeing 737-800 (OK-TVG) being operated by Travel Service on a passenger flight from Burgas, Bulgaria to Pardubice as TS2907 failed to stop before the end of the runway after landing off an approach in day VMC and continued onto firm grass for 156 metres beyond the end of the paved surface to the left of the extended runway centreline. None of the 194 occupants were injured and the aircraft was undamaged.

Investigation
An Investigation into the Serious Incident was carried out by the Czech Air Accident Investigation Institute (AAII). FDR and CVR data were successfully downloaded to assist the Investigation.

It was noted that both pilots had accumulated most of their flying hours on the Boeing 737, the 52 year-old Captain 8,175 hours out of a total of 14,778 hours and the 47 year-old First Officer 6,000 hours out of a total of 7,320 hours. Both pilots were "performing their duties for the airline company on a temporary basis" and both were familiar with Pardubice, a military aerodrome approved for civil air transport use. The First Officer was acting as PF for the investigated flight.

It was established that three days earlier, the aircraft had been released to service with the right engine thrust reverser deactivated in accordance with the MEL requirement for this action to be taken in the case of an inoperative reverser light. This was placarded as required and the crew were aware. A subsequent examination of the aircraft found no evidence of any other airworthiness deficiencies.

For the arrival at Pardubice, the ELW was 65,000 kg, just within the permitted MLW of 66,360kg. The ATIS received gave a tailwind for the approach to runway 27 which varied but wind checks from ATC gave it within the maximum permitted at all times - and it was subsequently shown from FDR data to have remained between 5 and 9 knots throughout.

There was, and had been for some time, intermittent light rain and the runway was wet.

After considering the various aspects of landing performance on the 2,500 metre long runway, it was decided to select Autobrake2 and use 30° land flap. A stabilised approach was flown and the aircraft crossed the runway threshold 46 feet agl before touching down very smoothly 821 metres into the runway - with almost one third of the 2,500 metre runway behind the aircraft. The pilots stated that they were not convinced that the speed brakes had deployed automatically and so they were selected manually and performed normally. No evidence of any system fault was subsequently discovered and it was considered possible that the two activations overlapped. Both pilots detected a deceleration which was slower than usual and Auto Brake 3 was selected. As the end of the runway approached, the Captain took over control, selected full manual braking and the operative left engine thrust reverser in what can be described as an attempt to direct the aircraft clear of the approach lighting on the extended centreline. The aircraft left the end of the paved surface at a recorded ground speed of 51 knots and came to a stop with the nose "turned by more than 90 degrees to the left". Once stopped, a PA - reported to have been inaudible in the passenger cabin - was promptly made stating "Cabin Crew at Stations". The Senior Cabin Crew then went to the flight deck and was informed (after the flight crew had established that there was no sign of fire or fluid leaks around the aircraft) that an emergency evacuation would not be necessary. Passengers were subsequently disembarked via a set of steps brought to the aircraft and then taken to the passenger terminal.



The aircraft as finally stopped showing its deviation to the left of the extended runway centreline to avoid the 09 approach lighting after leaving the end of the paved surface [Reproduced from the Official Report]

The Investigation noted that various details of the flight crew response once the aircraft had come to a stop, for example not shutting down the right engine until reminded to do so by a ground technician and instructing the senior cabin crew to disarm the slide and open Door 1L prior to the delivery of steps, were contrary to the Operator's applicable SOPs.

The FCOM landing performance data applicable to the landing made was examined and it was found that at the prevailing ELW, a flap 30 landing with auto brake 2 pre-selected plus a 70 kg addition for the inoperative thrust reverser would have required 90 metres more runway than was available even if the touchdown had been made within the TDZ. It was noted that a flap 40 landing in the TDZ with either auto brake 3 or full manual braking would have required only 1,840 metres plus an adjustment for the inoperative thrust reverser. A landing in the 09 direction would have avoided a tailwind component.

In respect of the deceleration actually experienced, it was also noted that the final approach had been intentionally flown "one dot low" which would have had the effect of delaying the touchdown, especially in the presence of a significant (although allowable) tailwind component. It was also considered that "braking action might have been influenced by the uneven distribution of the water layer on the runway profile" but noted that runway friction had been tested and found to be above the standardised Minimum Friction Level throughout.

It was noted that another of the Operator's Boeing 737-800 aircraft had been involved in a landing overrun event at Katowice, Poland earlier in 2013 but although this was known to be under investigation by the Polish authorities, "the results of (this) investigation had not been discussed with the Czech AAII up to the date of issue of this present Report".

The Cause of the overrun was formally recorded as "non-compliance with SOP by the crew and an incorrectly selected landing configuration for an aircraft of the Boeing B737-800 type under the given conditions at Pardubice".

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

• that Travel Service should adopt internal guidelines for monitoring of flight data and compliance with SOPs by their B737-800 crews.
  
• that Travel Service should, given the repeated occurrence of similar incidents, review training curricula for flight crew and the methodology for calculation of the distance needed for landing on contaminated runways.
  
• that Travel Service should adopt measures for flight and cabin crew training which are aimed at mastering the abilities to be applied to emergency procedures and disembarkation in the case of an aircraft (landing) overrun.
  
• that the Military and Civil Operators of Pardubice Airport should, on a regular basis, review the system of collecting data about the condition of aerodrome movement areas.
  
• that the CAA and the Military Aviation Authority should jointly propose procedures for the measurement of braking action at the national level given the regulatory changes in this area made by ICAO.
  

The Final Report of the Investigation was issued on 17 March 2014.

{P2 comment: Now beside the obvious breakdown in SOPs and possible indications of a culture of 'normalised deviance' within the airline's flight crew ops, that picture and the non-standard use of the 'operative left engine thrust reverser' gave me cause to reflect on another recent B737-800 runway excursion event, with similar picture and possible contributing factors, except it was in the TO roll - see HERE} 

Okay so another incident with elements of non-compliance and possible normalised deviance of SOPs in the causal chain. This would seem to be the theme that SMS company Baldwin Aviation are endeavouring to pick up on in yet another of their excellent safety awareness initiatives...  

MTF...P2