R101 - Official Inquiry

Official Inquiry

The Court of Inquiry was led by the Liberal politician Sir John Simon, assisted by Lieutenant-Colonel John Moore-Brabazon and Professor C E Inglis. The Inquiry, held in public, opened on 28 October and spent 10 days taking evidence from witnesses, including Professor Leonard Bairstow and Dr. Hugo Eckener of the Zeppelin company, before adjourning in order to allow Bairstow and the NPL to perform more detailed calculations based on wind-tunnel tests on a specially made model of R101 in its final form. This evidence was presented over three days ending on 5 December 1930. The final report was presented on 27 March 1931.

The Inquiry examined most aspects of the design and construction of R101 in detail, with particular emphasis on the gasbags and the associated harnessing and valves, although very little examination of the problems that had been encountered with the cover were made. All the technical witnesses provided unhesitating endorsement of the airworthiness of the airship prior to its flight to India. An examination was also made of the various operational decisions that had been made before the airship undertook its final voyage.

The possibility of the crash having been the result of a prolonged loss of gas caused by leakage or loss through the valves was discounted since this explanation did not explain the airship's behaviour during its last moments: moreover the fact that the officers on duty had changed watch routinely implied that there had been no particular cause for alarm a few minutes before the crash. The recent change of watch was considered to be a possible contributory factor to the accident, since the new crew would not have had time to get the feel of the airship. It was also considered most unlikely that the accident had been solely caused by a sudden downdraught. A sudden and catastrophic failure was seen as the only explanation. The Inquiry discounted the possibility of structural failure of the airframe. The only major fracture found in the wreckage was at the rear of the new framework extension but it was considered that this had either occurred on impact or more probably been caused by the intense heat of the subsequent fire. The Inquiry came to the conclusion that a tear had probably developed in the forward cover, this in turn causing one or more of the forward gasbags to fail. Evidence presented by Professor Bairstow showed that this would cause the R101 to become too nose-heavy for the elevators to correct.

The cause of the fire was not established. Several hydrogen airships had crashed in similar circumstances without catching fire. The inquiry thought that it was most probable that a spark from the airship's electrics had ignited escaping hydrogen, causing an explosion. Other suggestions put forward included the ignition of the calcium flares carried in the control car on contact with water, electrostatic discharge or a fire in one of the engine cars, which carried petrol for the starter engines. All that is certain is that she caught fire almost at once and burned fiercely. In the extreme heat, the fuel oil from the wreck soaked into the ground and caught fire; it was still burning when the first party of officials arrived by air the next day.

The Inquiry considered that it was "impossible to avoid the conclusion that the R101 would not have started for India on the evening of October 4th if it had not been that matters of public policy were considered as making it highly desirable that she should do so" but considered this to be the result of all concerned being eager to prove the worth of R101, rather than direct interference from above.