go back to passenger service The Soviet leadership made a political decision to enter the Tu-144 into passenger service in November 1977, despite receiving testing reports indicating that the Tu-144 airframe was unsafe and not airworthy for regular service. Aeroflot appears to have thought so little of the aircraft that it did not mention it in its five-year plan for 1976-1980. However, it was not the airline executives' decision and Aeroflot reluctantly put the Tu-144 into passenger service on 1 November 1977. Though the decision to cancel the Tu-144S passenger service came a few days after the Tu-144D crashed during the test flight on 23 May 1978, this crash was regarded as the last straw over mounting concerns about the reliability of the Tu-144. Even the fact that the technical reason for the crash was specific to the Tu-144D fuel pump system and did not apply to the Tu-144S did not help. The decision to pull the Tu-144S out of passenger service after merely 55 flights is thus more likely to be attributable to high incidence of failures during and before the scheduled flights. Cabin noise A problem for passengers was the very high noise level inside the cabin, measuring at least 90–95 dB on average. The noise came from the engines; unlike Concorde, it could only sustain supersonic speeds using afterburners, like military aircraft. In addition, the unique active heat insulation system used for the air conditioning, which used the flow of spent cabin air, was described as excessively noisy. Passengers seated next to each other could have a conversation only with difficulty, and those seated two seats apart could not hear each other even when screaming and had to pass hand-written notes instead. Noise in the back of the aircraft was unbearable. Aleksey Tupolev acknowledged the problem to foreign passengers and promised to fix it, but never had the means to do so. Seeking outside aid There were unprecedented Soviet requests for Western technological aid with the development of the Tu-144. The request was made despite obviously not helping to foster Soviet technological prestige, which was one of the key purposes of the Tu-144 programme. In 1977, the USSR approached Lucas Industries, a designer of the engine control system for Concorde, requesting help with the design of the electronic management system of the Tu-144 engines, and also asked BAC-Aérospatiale for assistance in improving the Tu-144 air intakes. (The