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Late Change of Intended Forced Landing Site

The AAIB Bulletin for November 2017 includes a tragic report of the crash of a Yak 52 flying out of Boscombe Down which led to the death of the front seat pilot, a tutor and service pilot from Boscombe Down, and the serious injury of the civilian flight instructor who was commanding the aircraft from the rear seat. This aircraft type has limited visibility from the rear seat and it was common for practice forced landings to be carried out by the front seat pilot. It is not known which pilot was flying at the time of the accident. The commander aged 60 years has a CPL and 2953 hours (446 on type and 15 in the previous 28 days). 

Shortly after completing a series of aerobatic manoeuvres, the engine lost power without warning. Attempts to restore power were unsuccessful and, at about 1,100 ft agl, the commander committed to a forced landing in a field. Evidence showed that the pilots probably became aware of a farm strip late in the approach to the intended field and made an attempt to land on the strip. The forced landing was unsuccessful and the aircraft struck the ground in a steeply left banked attitude at the southern edge of the strip. 

The November Bulletin also contains the report of the sad loss of life of the pilot of a mono-wheel Europa. He was aged 79 years and held a LAPL with 1146 hours (880 on type and 1 in the past 28 days). The report states that the aircraft took off from Coal Aston Airfield but did not achieve a normal rate of climb. At the end of the runway it turned to the left and then stalled, descending into an adjacent field. The pilot was possibly attempting to land back at the airfield. The evidence indicates that the engine suffered a partial loss of power, probably as a result of fuel vapour disrupting the fuel supply to the engine. It was found that the fuel vapour return line had been connected to the inlet of the fuel selector valve, rather than to the fuel tank. Any vapour in the fuel system was therefore routed back to the engine instead of returning to the fuel tank to dissipate. The accident was not survivable. 

Dr David Joyce, Chairman of the Europa Club and an occasional contributor to GASCo Flight Safety observes: 

The LAA has issued very clear guide lines on the requirements for a plane to be approved to use Mogas and these include running the return fuel line directly to the fuel tank and having the arrangement signed off by an inspector. In this case, someone had taken the easier option of connecting that line to the fuel supply line. 

The report quotes from the Skyway Code regarding partial engine failure:  

Particularly at low level, focus on maintaining speed and control. Provided you keep the aircraft at flying speed and under control, engine failures are unlikely to be fatal.
Partial engine failures can confuse the decision making process. Assess whether the failure is likely to become worse – for example if rapidly losing oil pressure, the engine may not run for much longer. Take a positive decision to either put down in a field or continue to an aerodrome, depending on your judgement of the problem.


There is also the following quotation from an ATSB Transport Safety Report (AR-2010-055): 

Partial engine power loss is more complex and more frequent than a complete engine power loss.
 

GASCo offers its sincere sympathy to the families and friends of those involved in these fatal accidents.  

There are also 15 Correspondence Reports in the November Bulletin of which no less than 10 are landing accidents, many of them at sites that presented rather more risk than would a licensed airfield. There are 3 take off accidents and one tumbling departure from controlled flight of a weight shift microlight ending in serious injury.  

Finally there is a forced landing of an Europa following engine failure. The AAIB report states that the pilot landed in the selected field, touching down at the point aimed for but the field turned out to be ridged and this led to minor injury of the pilot and major damage to the aircraft.  

However, that outturn was infinitely preferable to the alternative consequence of the pilot not making quite sure of flying the plane all the way down to the ground.  

Dr David Joyce observes in this instance: 

Landing across the ridges produced severe damage to the plane and a fractured spine for the pilot. It had not entered into the his head that there are fields about with deep furrows and he assumed that all grass fields would have a more or less level surface. In fact these ridge and furrow fields, dating from medieval times are still surprisingly common in some parts of the country and pilots would be well advised to look out for them in their area and to give some thought to the desirability of avoiding landing the wrong way across one. 


 

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