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Energetic particle precipitation into the atmosphere has been identified as a key loss process for electrons in the Earth's outer radiation belt region. However, direct measurements of the electron flux precipitating into the atmosphere are challenging from high altitude low inclination spacecraft, such as the Van Allen Probes, due to the small angular size of the loss cone along the orbital path of these high‐altitude spacecraft. Here we use data from the Polar Orbiting Environmental Satellites (POES)/Space Environment Monitor in low‐Earth orbit to assess the relationship between the trapped and precipitating electron flux in integral energy channels >30, >100, and >300 keV. Our results highlight that there is a strong non‐linear relationship between the flux of trapped and precipitating electrons, with the ratio of precipitating to trapped flux only becoming significantly enhanced once the trapped flux reaches a critical level. This transition from low to high levels of precipitation is consistent with the theory proposed by Kennel and Petschek (K‐P) (1966) https://doi.org/10.1029/JZ071i001p00001, whereby intense chorus waves are excited and trigger pitch angle diffusion, resulting in energetic particle precipitation and limiting the trapped flux. Using electron flux data from POES and chorus wave data from the Van Allen Probes, we further test the observations against predictions from the K‐P theory. A particle tracing model is also utilized to illustrate a direct link between the drift paths of injected electrons, the occurrence of chorus waves and the spatial distribution of strong electron precipitation into the atmosphere at different energies. Key Points: Trapped and precipitating electron fluxes become equal once the trapped flux hits a flux limit, indicating strong diffusion is occurringEvents with both high trapped and precipitating flux occur more often in the dawn sector, matching the drift paths of injected electronsIntense chorus waves occur mostly near dawn, suggesting injected electrons excite them and limit the flux via a Kennel‐Petschek‐like process [ABSTRACT FROM AUTHOR]

Electron lifetimes are important for understanding the dominant loss processes of radiation belt electrons to the atmosphere and for accurate radiation belt modeling. We estimate electron lifetimes from the precipitating population measured in Low Earth Orbit (LEO) from the Polar Orbiting Environmental Satellites (POES). We compare our estimates to previous estimates from the Radiation Belt Storm Probes (RBSP) by Claudepierre et al. (2020b, https://doi.org/10.1029/2019GL086053). We also present the first complete pitch angle resolved lifetimes in the radiation belts. Quasi‐linear theory predicts the pitch angle distribution decays uniformly, therefore if steady‐state decay is realized, POES and RBSP should measure similar lifetimes. Lifetime estimates from LEO are shown to be in good agreement with those from Van Allen Probes in the outer belt and pitch angle resolved lifetimes indicate that steady‐state decay is realized. However, a systematic slight overestimation of the POES lifetimes reveal that the POES instruments may suffer from bremsstrahlung contamination. At L = 2–3, no decay intervals were identified in the POES electron fluxes and the near loss cone RBSP electron fluxes. We show that at these L‐shells, where lifetimes are long, there is an apparent decoupling of the perpendicular and parallel flux. Large pitch angle anisotropy and processes that affect low pitch angle electrons are two explanations for this apparent decoupling. Electron lifetime models that use pitch angle independent lifetimes, derived from the equatorially mirroring electron flux, likely underestimate the amount of precipitating flux and may not capture the dynamics of low equatorial pitch angle electrons at L < 3. Key Points: Lifetimes between Polar Orbiting Environmental Satellites (POES) and Radiation Belt Storm Probes in the outer belt agree, though POES may suffer from bremsstrahlung contaminationPitch angle independent (equilibrium) decay is realized in the outer radiation beltVarious processes decouple the perpendicular and parallel flux preventing the identification of decay intervals from Low Earth Orbit at L = 2–3 [ABSTRACT FROM AUTHOR]