James Stansfield of the website Den of Geek considers "Attack on Cloudbase" to be the best episode of "Captain Scarlet". Describing the episode as highly entertaining even if "shocking and surprisingly bleak", he praises the writing and characterisation – in particular, the death of Rhapsody Angel and the conflict between Blue and White. However, he comments negatively on the dream plot twist as well as what he regards as a minor plot hole: for reasons that are unclear, the stranded Symphony throws away her helmet, thus making it impossible for Spectrum to contact her. Stansfield suggests that the nightmarish nature of the plot is implied long before it is confirmed in dialogue, suggesting that moments such as the death of the "indestructible" Scarlet, and Blue's lack of astonishment at the sudden appearance of Captain Black, serve as "hints ... that all might not be quite as it seems". In 2019, British magazine "TV Years" (a sister publication of "TV Choice") listed the attack sequences as the 23rdgreatest moment in TV science fiction, calling the episode "devastating" up until the plot twist.