R101 Despite the lack of full endurance and speed trials and the fact that a proper investigation of the aerodynamic consequences of the extension had not been fully completed by the N.P.L., a Certificate of Airworthiness was issued on 2 October, the Inspectorate expressing their complete satisfaction with the condition of the R101 and the standards to which the remedial work had been carried out. The actual certificate was handed over to H. C. Irwin, the ship's captain, only on the day of her flight to India. R101 departed from Cardington on the evening of 4 October 1930 for its intended
R101 new course was set to bring R101 over Orly, based on an estimated wind direction of 245 degrees and speed of . The intended course would have taken R101 four miles west of Beauvais, but the estimated wind speed and direction were inaccurate, as a result of which the 101's track was to the east of its intended course. This error would have become apparent when, at about 01:00, R101 passed over Poix-de-Picardie, a distinctive hilltop town that would have been readily recognisable to the navigation officer, Squadron Leader E.L. Johnston. Accordingly, R101 changed course: the new course would take