  Context. The existence of meteor clusters has long since been a subject of
speculation and so far only seven events have been reported, among which two
involve less than five meteors, and three were seen during the Leonid storms.
Aims. The 1995 outburst of Comet 73P/Schwassmann-Wachmann was predicted to
result in a meteor shower in May 2022. We detected the shower, proved this to
be the result of this outburst, and detected another meteor cluster during the
same observation mission. Methods. The {\tau}-Herculids meteor shower outburst
on 31 May 2022 was continuously monitored for 4 hours during an airborne
campaign. The video data were analyzed using a recently developed
computer-vision processing chain for meteor real-time detection. Results. We
report and characterize the detection of a meteor cluster involving 38
fragments, detected at 06:48 UT for a total duration of 11.3 s. The derived
cumulative size frequency distribution index is relatively shallow: s = 3.1.
Our open-source computer-vision processing chain (named FMDT) detects 100% of
the meteors that a human eye is able to detect in the video. Classical
automated motion detection assuming a static camera was not suitable for the
stabilized camera setup because of residual motion. Conclusions. From all
reported meteor clusters, we crudely estimate their occurrence to be less than
one per million observed meteors. Low heliocentric distance enhances the
probability of such meteoroid self-disruption in the interplanetary space.
