In the bombardment of a 244Pu target with 48Ca ions, we observed two identical decay sequences of genetically linked events, each consisting of an implanted heavy atom, two subsequent α decays, and terminated by a spontaneous fission. The measured α energies and corresponding half-lives of the sequential chain members were Eα=9.84+/-0.05 MeV (T1/2=1.9+3.3-0.8 s) and 9.17+/-0.05 MeV (T1/2=9.8+18-3.8 s) for the spontaneous fission (T1/2=7.5+14-2.9 s), the total energies deposited in the detector array were 213+/-2 and 221+/-2 MeV. The decay properties of the synthesized nuclei are consistent with the consecutive α decays originating from the parent even-even nucleus 288114, produced in the 4n-evaporation channel with a cross section of about 1 pb. 288114 and 284112 are the heaviest known α-decaying even-even nuclides, following the production of 260Sg and 266Sg (Z=106) and the observation of α decay of 264Hs (Z=108). The observed radioactive properties of 288114 and the daughter nuclides match the decay scenario predicted by the macroscopic-microscopic theory.